Yearbook: 2000-2001

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INSTITUTE OF CONCRETE TECHNOLOGYP.O.BOX 7827, Crowthorne, Berks, RG45 6FR

Tel/Fax: (01344) 752096Email: ict@ictech.org

Website: www.ictech.org

THE ICTThe Institute of Concrete Technology was

formed in 1972 from the Association ofConcrete Technologists. Full membership isopen to all those who have obtained theDiploma in Advanced Concrete Technology.The Institute is internationally recognised andthe Diploma has world-wide acceptance asthe leading qualification in concretetechnology. The Institute sets higheducational standards and requires itsmembers to abide by a Code of ProfessionalConduct, thus enhancing the profession ofconcrete technology.

AIMSThe Institute aims to promote concrete

technology as a recognised discipline and toconsolidate the professional status ofpractising concrete technologists.

PROFESSIONAL ACTIVITIESIt is the Institute's policy to stimulate

research and encourage the publication offindings and to promote communicationbetween academic and commercialorganisations. The ICT Annual Conventionincludes a Technical Symposium on a subject oftopical interest and these symposia are wellattended both by members and non-members. Many other technical meetings areheld. The Institute is represented on a numberof committees formulating National andInternational Standards and dealing with policymatters at the highest level. The Institute isalso actively involved in the education andtraining of personnel in the concrete industryand those entering the profession of concretetechnologist.

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ICT YEARBOOK 2000-2001

EDITORIAL COMMITTEE

Professor Peter C. Hewlett (Chairman)BRITISH BOARD OF AGRÉMENT

& UNIVERSITY OF DUNDEE

Peter C. OldhamCHRISTEYNS UK LIMITED

Dr. Bill PriceSANDBERG

Graham TaylorINSTITUTE OF CONCRETE TECHNOLOGY

Laurence E. PerkisINITIAL CONTACTS

Published by:THE INSTITUTE OF

CONCRETE TECHNOLOGYP.O.Box 7827Crowthorne

Berks RG45 6FREmail: ict@ictech.org

Website: www.ictech.org

£50.00

ISSN 1366 - 4824

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Yearbook: 2000-2001

CONCRETE TECHNOLOGYINSTITUTE OF

The

CONTENTS PAGE

FOREWORD 5By Mike Connell, President, INSTITUTE OF CONCRETE TECHNOLOGY

THE INSTITUTE 6

COUNCIL, OFFICERS AND COMMITTEES STRUCTURE 7

FACE TO FACE 9 - 12A personal interview with Professor Peter Hewlett

MILESTONES IN CONCRETE HISTORY: 13 - 20ADVANCES IN CONCRETE TECHNOLOGY DURING THE FIRST WORLD WAR. By: Peter Oldham

ANNUAL CONVENTION SYMPOSIUM: 21 - 56PAPERS PRESENTED 2000

ANNUAL CONVENTION SYMPOSIA: 57 - 60PAPERS PRESENTED 1988 - 1999

ADVANCED CONCRETE TECHNOLOGY DIPLOMA: 61 - 72SUMMARIES OF PROJECT REPORTS 1999

INDEX OF PROJECT REPORTS PRESENTED AS PART OF THE 73 - 95ADVANCED CONCRETE TECHNOLOGY COURSE FROM 1971

RELATED INSTITUTIONS & ORGANISATIONS 96

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FOREWORD

5

ome say it came in with a bang andsome say it came with a whimper but weare now in the year AD 2000 and, at the

time of writing, it looks as if some fairly large-scale changes are happening in the concreteand cement industries as company mergersand take-overs unfold. The growth of somecompanies, with the resultant reduction in thenumber of operating organisations and theloss of some company titles which are almosthousehold names, has been a constant factorfor many years but it certainly seems to haveaccelerated recently. A substantial number ofour members are directly affected and I feelthat most readers of this Yearbook will join mein wishing that all involved personnel are notadversely affected by these changes andreorganisations.

The last 12 months have, on the whole,been fairly good in business terms with goodlevels of production and construction activity,many members reporting high levels ofcustomer demand for construction materialsand services. This healthy position is welcomeafter some lean years and looks set to continuein respect of enquiries for future work. Theaffairs of the Institute have continued to beably managed by Council and the variouscommittees and the Institute remains gratefulto employers for allowing time and providingfacilities without which many tasks would beextremely difficult. I am pleased to report thatthe ACT course is presently being run at threelocations - in South Africa, Ireland andNottingham. In recognition of the relativelystatic number of current ICT members anattempt is being made to boost membershiplevels by at least 5% per year. The Institute isalso working towards achieving IncorporatedEngineer status for our members and is takingsteps to raise our profile within industry. Ourwebsite (www.ictech.org) continues to be ofinterest to many and a large number of visitorshas been recorded.

We have completed the first full year ofContinuing Professional Development and arepresentative sample of members havereceived requests from Council to submit theirrecords. Whereas the recording of training andassociated activities can be seen as yet anotherunwanted task, it is a fact of life that CPD hasto be seen to be monitored if the status of aqualification and membership is to bemaintained. One of the simplest ways for a

member to achieve a good portion of therequired hours is, of course, to attend theannual Convention. Some of the paperspresented at this year’s Symposium appear inthis Yearbook and the range of topics illustratesthat the material which we all know from ourown particular viewpoint is also seen frommany other perspectives. Readers will also seethat this Yearbook contains new articles tosupplement the Convention papers and I wishto thank and congratulate Professor PeterHewlett and his Editorial Committee forproviding some interesting and thoughtprovoking reading.

S

MIKE CONNELL PRESIDENTINSTITUTE OF CONCRETE TECHNOLOGY

6

INTRODUCTIONThe Institute of Concrete Technology

was formed in 1972 from the Association ofConcrete Technologists. Full membership isopen to all those who have obtained theDiploma in Advanced Concrete Technology. TheInstitute is internationally recognised and theDiploma has world-wide acceptance as theleading qualification in concrete technology.The Institute sets high educational standardsand requires its members to abide by a Code ofProfessional Conduct, thus enhancing theprofession of concrete technology.

MEMBERSHIP STRUCTUREThe ‘Routes to Membership’ were officially

launched following the 1999 Annual GeneralMeeting. A guide on ‘Routes to Membership’has been published and circulated to allmembers as part of the MembershipHandbook. The guide contains full details onthe qualifications required for entry to eachgrade of membership.

A FELLOW shall have been a CorporateMember of the Institute for at least 10 years,have a minimum of 15 years relevantexperience, including CPD records from the dateof introduction, and be at least 40 years old.

A MEMBER shall hold the Diploma inAdvanced Concrete Technology and will have aminimum of 5 years relevant experienceincluding CPD. This will have beendemonstrated in a written ‘Technical andManagerial/Supervisory Experience Report’. Analternative route does exist for those notholding the ACT Diploma but is deliberatelymore onerous. Details are contained within theguide on ‘Routes to Membership’. A Membershall be at least 25 years old.

AN ASSOCIATE shall hold the City andGuilds CGLI 6290 Certificate in ConcreteTechnology and Construction, General Principlesand Practical Applications. They shall also have aminimum of 3 years relevant experiencedemonstrated in a written report. Alternativeroutes exist for Graduate members where anappropriate university degree will exempt themfrom the requirement to hold CGLI 6290qualifications. In addition those who havepassed the written papers of the ACT coursebut have yet to complete their Diploma mayalso become Associate members. All candidatesfor Associate membership will be invited tonominate a corporate member to act asSuperintending Technologist. There is nominimum age limit in this grade.

A TECHNICIAN shall hold the CGLI5800 Certificate in Concrete Practice and submita written report demonstrating 12 monthsexperience in a technician role in the concreteindustry. An alternative route exists for thosenot holding the CGLI 5800 Certificate but whocan demonstrate a minimum of 3 years relevant

experience in a technician role. All candidates forTechnician membership will be invited tonominate a corporate member to act asSuperintending Technologist. There is nominimum age limit in this grade.

A GRADUATE shall hold a relevantuniversity degree containing a significantconcrete technology component. All candidatesfor Graduate membership will be invited tonominate a corporate member to act asSuperintending Technologist. There is nominimum age limit in this grade.

The STUDENT grade is intended to suittwo types of applicant.

i) The school leaver working in theconcrete industry working towards theTechnician grade of membership.

ii) The undergraduate working towards arelevant university degree containing asignificant concrete technologycomponent.

All candidates for Student membership willbe invited to nominate a corporate member toact as Superintending Technologist. There is nominimum age limit in this grade. There is a limitof 4 years in this grade.

Candidates are not obliged to attend anycourse (including the ACT course) prior to sittingan examination at any level.

It is no longer necessary for a candidate tohave relevant experience prior to being admittedto the ACT course. Academic qualifications andrelevant experience can be gained in any orderfor any grade of membership.

Corporate members will need to becompetent in the science of concretetechnology and have such commercial, legaland financial awareness as is deemed necessaryto discharge their duties in accordance with theInstitute’s Code of Professional Conduct.

Continuing Professional Development(CPD) is common to most professions to keeptheir members up to date. The Institute’s CPDscheme came into effect from April 1999. Allcorporate members are obliged to spend aminimum of 25 hours per annum on CPD;approximately 75% on technical developmentand 25% on personal development. TheInstitute has published a guide on ‘ContinuingProfessional Development’, which includes arecord card for each member. This is included inthe Membership Handbook. Annual randomchecks will be conducted in addition toinspection at times of application for upgradedmembership.

ACT DIPLOMAThe Institute is the examining body for

the Diploma in Advanced Concrete Technology.Courses for the Diploma are currently held in theUnited Kingdom, Ireland and South Africa.Details are available from the Institute.

THE INSTITUTE

7

Dr. J.D. DEWARChairman

G. TaylorSecretary

Dr. Ban Seng Choo

S. Mac Craith

Dr. P.L.J. Domone

R. Gaimster

Dr. J.B. Newman

H.T.R. du Preez(corresponding)

R. Ryle

R.V. Watson

J.D. Wootten

M.D. CONNELLPresident

Dr. W.F. PriceVice President

R. GaimsterHon.Secretary

J.C. GibbsHon.Treasurer

R.E.T. Hall

C.D. Nessfield

P.C. Oldham

B.F. Perry

H.T.R. du Preez(corresponding)

A.R. Price

G. Prior

K.F.C. Weston

W. Wild

Dr. W.F. PRICEChairman

J.V. TaylorSecretary

M.W. Burton

G.W. David

R. Hutton

J. Lay

A.R. Price

Dr. P.J. Wainwright(corresponding)

A.T. Wilson

J.C. GIBBSChairman

G. TaylorSecretary

M.D. Connell

P.M. Latham

Dr. W.F. Price

K.W. HEADChairman

J.C. GibbsSecretary and Treasurer

L.R. Baker

R.C. Brown

H.T. Cowan

G. Prior

J. Wilson

R.A. Wilson

P.M. LATHAMChairman

G. TaylorSecretary

R.G. Boult

P.C. Oldham

G. Prior(corresponding)

A.R. Rogers

EXECUTIVEOFFICER

G. TAYLOR

A.R. PRICEChairman

G. TaylorSecretary

M.D. Connell

C.D. Nessfield

J.D. Wootten

H.T. BENNChairman

H.T.R. du PreezSecretary

J. Kellerman

EXAMINATIONSCOMMITTEE

COUNCILTECHNICAL AND

EDUCATIONCOMMITTEE

FINANCECOMMITTEE

ADMISSIONS ANDMEMBERSHIPCOMMITTEE

SCOTTISH CLUBCOMMITTEE

EVENTSCOMMITTEE

SOUTHERNAFRICA CLUBCOMMITTEE

MARKETINGCOMMITTEE

B.F. PERRYChairman

C.D. Nessfield

A. Scothern

G. Taylor

COUNCIL, OFFICERS AND COMMITTEES STRUCTURE

8

9

Any meeting with Peter Hewlett is sprinkledwith humour and wit but is always purposeful.He has the ability to make you feel welcomeand comfortable.

Q: Peter, I understand that you have avery full diary and your frequent travelsand many appointments andresponsibilities must keep you fullyoccupied. Could you tell me how youmanage to maintain your obviousenthusiasm for the many tasks youundertake?

A: Firstly, I enjoy what I do and I enjoy beingbusy, probably at the expense ofconventionally enjoyable pastimes. I choose towork, which I take great pleasure in, so Isuppose the motive is a little selfish.Fortunately, I have a very co-operative wife andfamily. My enthusiasm is not directed uniquelyto the area of building and constructionmaterials but is for the whole learning process,which I maintain. As a non-engineer workingwith engineers and in engineering, I have theopportunity to break down some of thebarriers and the need to communicate I havealways found very stimulating and still do. Ihave maintained my lecturing, although I don’thave to, and I find this an excellent way oflearning. I think I’ve been very fortunate that Iwas given the opportunity of involvement at arelatively young age, in an environment thatwas crying out for some basis of explanationand the transfer of science into a verypragmatic activity. The purist would say thatthe science was therefore perhaps, secondorder. Even so, in my view it is very necessary.

Q: Have you found concretetechnologists to be receptive?

A: Personally I have because I talk with themand not at them. I am also prepared to listen.

Q: Turning to your career, tell me aboutyour PhD.

A: Having qualified as a chemist, I was veryinterested in doing chemistry allied to medicineand my PhD had its roots in the biochemistryof the haemoglobin/oxyhaemoglobin reaction.As this followed on from my degree, I misseddoing National Service by two days; somethingwhich I have regretted - the discipline that is,not the mindless boredom.

Q: How did you progress after that?

A: My first job was as a project chemist withCementation Research, then a very newcompany. I became Head of the ChemistrySection and then the Science Division(Chemistry combined with physics) for anumber of years. In about 1972 I becameTechnical Director of Cementation Chemicals(the youngest in the Group!) which providedchemicals to Cementation’s specialistengineering companies, and then Director ofResearch of Cementation Research for 12years. In all, over this period, I acquired sixDirectorships. I enjoyed the variety becauseworking for engineers it involved every aspectof building and construction and the perennialmatter of technical communication.

FACE TO FACE

A personal interview with Professor Peter Hewlett

For the past quarter of a century the Institute haselected eminent people from within the cement andconcrete industry as Honorary Fellows. One of those isPeter Hewlett, Director of the British Board of Agrément.His influence is evident from the range of activities heundertakes in his 17-hour working day: Visiting Professorat the University of Dundee; Immediate Past President ofthe Concrete Society; lecturer on the ACT course; editor ofthe latest edition of Lea’s Chemistry of Cement andConcrete; sitting on numerous committees and Chairmanof the Editorial Committee of this Yearbook. He has beenan unfailing supporter of the Institute and has presentedpapers at and chaired our annual symposium on severaloccasions. It is therefore a great pleasure to present thisinterview with him as the first in the series.

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Q: Why then, in middle age and witheverything going sweetly, did you want toleave?

A: I had reached the point where I had toknow what I couldn’t do. This is a veryperverse motive and with the male menopauseyou have this urge to break out and take achance and it took me 2-3 years of lookingbefore I settled on the present job, which Ihave now held for over 12 years. Everyemployer I have worked for has judged me onwhat I have done and am doing and if theyhave been satisfied with that, they haveallowed me to set my own agenda - a veryprivileged position and one I will always begrateful for.

Q: Have there been any milestones inyour time at BBA?

A: Yes and the learning process continues. Iwas somewhat surprised and abashed onjoining the BBA that I didn’t know what aBuilding Regulation was; I also had very scantidea of the overall activity of construction andtherefore I was coming from quite a differentdirection but whilst it no longer includedresearch as mainstream activity it was dealingwith innovation and its adoption into bestpractice.

What we do at BBA is sell reassurance, securityand confidence to our customers and thecustomer’s customer and we should notdemean this. In these competitive times it isvery easy to sell myths but if the process ofapproval and certification, and approval andcompliance, are going to be worth what theyshould be, they have got to be complete andhave proven integrity. I am reassured that thebasic capability and the range of disciplinesthat reside within BBA mean that we do thingsthe only way, correctly.

Q: Whilst I’m sure that many ICTmembers know of BBA, some may beunsure what BBA does?

A: We carry out performance basedassessments on products and systems that donot necessarily have a track record in practice.The purpose of that is to encourage theadoption of responsible innovation into bestpractice. What we provide is not mandatory,not required in law, and therefore people canwalk away. Independence and impartialityhave to live alongside the realities of business.

Agrément actually means pleasure, althoughthe process of agrément is not a pleasure, it isquite difficult. We find that people don’t knowhow to demonstrate adequacy - fitness for use

is greatly misunderstood; the very word‘quality’ talks things up. Quality is defining thepurpose and then being able to reproduce thatperformance consistently to meet theaspirations of the client.

Q: Why did you re-edit Lea’s mammothbook?

A: Technology has moved on and the fourthedition was rapidly becoming outdated but theassociation with Lea, and the area ofinnovative thinking on cementitious materials,was always very desirable to maintain. It tooknine years and was an onerous task but I hopeit maintains its currency for at least a decade.In many ways it’s a re-write; there are newchapters but I feel that Lea would stillrecognise it. I learnt a lot whilst doing it -about the science, the technicality and aboutpeople!

Q: Tell me about your three terms asPresident of the Concrete Society.

A: The first one was a delight and I was veryflattered to be asked. I seem to get involvedwith things that have problems and things thatare under change. The Society had to searchfor an identity, perhaps different to the dualrole of a learned society and a comfortable cluband ask ourselves ‘should there be morepurpose and drive’, so that a lot of re-thinkinghad to come into play. When it was suggestedthat I should do a second term, I felt a certainamount of responsibility to carry thesechanges through, having helped to determinethe new direction. The third term was notexpected. The President-Designate resignedand I was in a good position to act as a sort ofnightwatchman. That was beneficial becausethe Society now has its prospectus for thefuture and quite a brave one - I support thenew initiative and hope it succeeds.

Q: You said earlier that you leftCementation to find out what youcouldn’t do. Have you found that out?

A: I’m not sure but I think that I havelearned some things. Certainly things aboutthe industry we work in and also personally.For instance, how to be a little more patient. Iwas always very much in a hurry and I don’tthink I’m in any less of a hurry now butperhaps more consensus oriented thanpreviously. My rush relates first tounderstanding and then applying thatunderstanding beneficially. I have neverbelieved the majority of people in research, orwho have invented things, are happy with thenon-application of their work.

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Q: What do you see as the future ofcement and concrete research?

A: I think the future already has guidelineslaid down and I think that the issues to beaddressed, as in other areas, will be thecontainment of energy requirements, such asin the production of cement, or in alternativematerials that don’t have the same energyburden. We are going to hear more aboutsustainability and within that a sub-set inrelation to the use of secondary and tertiarymaterials in order to maintain the sustainabilityaspects. In the case of concrete and mortars,I feel no less enthusiasm for the subject than Idid 30 years ago. My personal view is that wehave only scratched the surface of concrete’scapabilities but regard has to be taken of costs.

I would ask the question; does it excite ordepress others that we can make concrete of200MPa when most commonly it is less than60 MPa? It excites me because it shows theextent to which things can be changed andthis creates opportunity.

Future concrete is limited solely by ourimagination not limited fundamentally. Sincethe war the concepts in the uses of concretehave changed. Innovation has acceleratedsubstantially in the last 10 years but the spurtends to be the difficult contract or situation. Iremember secret conversations with agentleman at the C&CA in the sixties onadmixtures, which was not a respectablesubject then. Nowadays these materials arewell-integrated into good concrete and will goon until, in 10-20 years time, we will wonderwhy it was ever otherwise.

Q: There must be a natural reluctance touse admixtures, especially as manyremember calcium chloride, which didn’tperform as it should have done.

A: This is true. There has to be a will and thetechnology has to be sound. As far as calciumchloride is concerned, many of the inheritedproblems associated with this had their roots inmisuse rather than inherent inadequacy. Thelegacy of caution and the demand for soundknowledge of these materials may not be abad combination.

Q: There is also the input of people.What are your feelings about the trade ofconcretor?

A: 25 years ago Steve Arnold of the RoyalCollege of Military Science at Shrivenham madea very cogent case for recognising the skill. Helost the battle. Every now and then it raises itshead and it is in focus now. We have other

recognised trade skills and I find it very strangethat that of concretor remains unrecognised,which in some way is disparaging. Judging forthe Concrete Society, on behalf of the AnnualAwards, I have seen concrete that is superb,visually and functionally. So we shouldn’t betoo preoccupied with the failures and theinadequacies. We should also be preoccupiedwith the best that can be achieved. I askmyself, why isn’t that the norm rather thanaccepting as the norm that which isinadequate. If we accept the best as beingnormal, that’s a challenge but we come backreally to the wish and will to respond to thechallenge. All other building activities havesome recognised skills. With concrete, the skilland the requirement is played down. Ifcontractors are truly committed to quality theywill require workmen with the necessary skills.Current initiative through the organisationConstruct is a positive move in this direction.

When you look at cement production and theready-mix industry, and the evolution of qualitymanagement systems for the production ofthe basic materials, which is probably one ofthe highest quality materials within its pricerange, and you look at how the ready-mixindustry has imposed a discipline on the routeto improvement and reassurance, there havebeen changes and these changes can takedecades. So, if you are looking for change overa year or two, forget it, it’s not the way theindustry is created. But looking back you cansee that it has progressed. My worry is; canconcrete compete with other materials such astimber and steel and I think that it can. But wehave got to adopt the same sort of focus thatin the case of steel has been very successful.But steel production and use are not asdisparate an industry as is concrete. That canbe a strength but it also means that you havegot many mouths to feed and many attitudesto take on board.

Q: You have obviously made manyfriends in the industry.....

A: I’d like to think so. I’ve enjoyed it and stillenjoy it. I find that people who stay in thisindustry have a genuine enthusiasm and thatis infectious. They can also be enquiring.Coming from a research background I thinkthat that is a very privileged position.

Q: Who are your best friends?

A: I don’t want to answer that!!

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Q: You appear to have interests inindustry and academia. Do these clash?

A: No. I couldn’t do without my interest inacademe. Had I not got the job withCementation I would probably have ended upin a university. I have never found academeand industry incompatible. Lecturing touniversities and industry is a very necessaryand selfish activity for me. It’s a honing stone.I find that the purposefulness of industry isstimulating and I find that interfacing that withfocused research that has at its core a desirefor it to be useful, also very stimulating. I havebeen fortunate in always managing to get ablend of the two.

My professorship at Dundee that I have heldnow for some 15 years has been veryrewarding and the award to me of anHonorary Doctor of Laws Degree for my workon surface properties and durability of concretein conjunction with Professor R K Dhir mostgratifying.

Q: Does industry appreciate academia?

A: I think they appreciate the product ofacademia; the knowledge and problem solvingcapability but they don’t necessarily appreciatethe process that leads to these outcomes. Butthey could always do what I did and that ismake sure that the voice of your area ofindustry is heard within academe and viceversa. It is a very necessary ying and yang.

Q: You seem to do a fair amount ofaircraft mileage. What is your most recenttrip?

A: To Poland and the USA. Much to mysurprise I was awarded what the Polish call theOfficers Cross of Merits for outstandingcontribution to scientific and technological co-operation. I was delighted but surprisedbecause this accolade is not usually given toforeigners. It reflects, I think, the work that I didwhilst president of the European Organisationfor Technical Approvals to bring in the oldeastern block countries as candidate countriesto the EU at a technical level. The institutesinvolved are very competent and keen andmake a welcome technical input.

Q: Tell me a little about your family

A: I was married in 1962, toward the end ofmy PhD. My wife Anne has been a staunchsupporter and soul mate throughout mycareer.

We have two children, a daughter and a sonand they are both married. Our daughter is abio-chemist, has a PhD and is quietly

industrious. Our son is a geographer and isnow teaching. He is a very good organiser ina quiet, unassuming way and although quitefirm in his views, he imbues confidence. We area fairly average family.

Q: Other interests apart from work?

A: Classic motor cars have always interestedme, although I have never owned a car of myfirst choice - always an inadequacy. Now thatI have the funds to do so, I have lost thecourage! The car of my choice would be a 41/2litre 1927/1930 open Bentley. I am a regularfrequenter of classic car racing circuits and Ifind that one can be part of it without thepride of ownership. Apart from that, I like togo to the theatre and we support the local onein Watford but not as much as we should,perhaps a point for the future.

I used to do some sailing but I’m not happyfaffing around on ponds. When you’re sailingyou can’t do anything else and it can berelaxing - cruising that is, not racing.

Q: If you had to retire at 65 what wouldyou do?

A: Probably look for a job!! I don’t mindspending an hour or two in the garden,preferably in a deck chair with a drink. We havea nice garden but my wife is the gardener.

Q: Give me one example of a recenthighlight.

A: I represented the Concrete Society at aBuckingham Palace garden party celebratingPrince Charles’ 50th Birthday. It is notoriouslydifficult to interest someone like John Major orsome foreign ambassador when making politeconversation to wax on about concrete. Howmany people have regard for concrete?Notwithstanding the fact that they drive on it,use it every day, the coast is protected by it,and we might not have liberated Francewithout it. Yet its perception is poor. Weshould take that low perception of concreteand challenge it because concrete can beabsolutely beautiful; Nervi’s elegant traceryshows what can be done. Now that we canmake it tough as well as strong and durable, itopens up a new chapter of opportunity.

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BackgroundWhen Britain went to war in August 1914

concrete was a rather less well understoodmaterial than it is today. Whereas a number oflarge and important reinforced concretestructures had been successfully completedand the number of concrete buildings hadbeen steadily growing since about 1850, it wasstill a relatively little used material produced byspecialist contractors. Traditional systems suchas stone masonry and lime-based mortarswere more commonly used in construction.

The military use of the material had beenexamined by the Royal Engineers over thelatter part of the 19th century but they hadnot found it to be very suitable for theirpurposes as most actions fought by the BritishArmy over this period had been mobile andinvolved mobile infantry and cavalry. TheAdmiralty, together with the Royal Artillery, hadtaken more interest, however, as they wereconstantly maintaining Britain’s coastaldefences and several forts guarding ports andharbours were strengthened following a RoyalCommission report on the state of the nationsdefences and the resultant Fortification Act of1867. The threat of invasion by the French,either by a direct assault on a port or harbourby a French fleet or by a military force whomight land on an unprotected coast and travelinland to take the port from the rear, wasthought was to be a real possibility.

Developments in artillery science had

resulted in the development of explosivemissiles based on picric acid and melinite , orhigh explosive, which had greater burstingpower than earlier explosive shells, and fuseswhich allowed some penetration beforedetonation, lead the Admiralty to strengthencurrent shell proof building designs. Astandard method for some renovation andnew work was based on the use of steel platesand granite masonry, an asphaltic concrete mixof iron swarf, bitumen and pitch was used tojoint the masonry and as a thick covering bedto act as a resilient layer and absorb the shockof an explosion. Following artillery trials manycasemates and artillery defences were laterfurther strengthened with concrete based onPortland cement although long term shrinkagecracking, which reduced the ability towithstand the effect of disruptive explosions,was seen as a major fault. Political situationsbetween Belgium, France, Germany and otherEuropean countries, where fortification hadbeen studied more closely over the centuries,were becoming more complicated as the 19thCentury closed and fortification engineers suchas de Riviérès and Brialmont, following earlierworks by engineers such as Vauban, weredesigning defences with 2.5m thickness ofreinforced concrete. Many of the laterrefinements and technological advances inEuropean defences were the result of studiesof damage caused by heavy artillery during theFranco-Prussian war. Britain gained littleexperience from this as it was thought unlikely

MILESTONES IN CONCRETE HISTORY.

The technology of cement based materials has been developing since the first concrete mixwas produced. Much of this technology was further improved with time but much was forgotten(sometimes to be later ‘reinvented’). Some developments have been accidental, such as thediscovery of the benefits of air entrainment. Some have been the result of foresight andendeavour, or for commercial gain, whilst some have been borne of necessity such as those formilitary and structural reasons.

This series of articles - ‘Milestones in the history of concrete technology’, will include someof the more important steps which the science of materials has taken. Later papers may includethe work of pioneers such as Vicat, Hennebique and Powers; the early use of admixtures; Roman,Victorian and Portland cements; the work of the Cement and Concrete Association; no finesconcrete; the advent of precast buildings and Brooklands historic race track construction.

This first paper in the series details the advances in materials technology during the periodwhen industrialised warfare necessitated rapid improvements in the strength of concretestructures.

ADVANCES IN CONCRETE TECHNOLOGY

DURING THE FIRST WORLD WAR. By: Peter Oldham

14

that we would be caught up in continentalstyle static warfare or sieges such as that ofParis.

The Royal Engineers had meanwhile nottotally neglected the properties and potentialbenefits of concrete. In South Africa in 1900about 440 light field artillery-proof machinegun and infantry positions had beenconstructed at strategic locations along railwayand defence lines such as the Elandsfontein-Vereeniging line to protect against raids byBoers. Most of these were of locally quarried,mortar jointed masonry construction althougha small number were made of unreinforcedconcrete. The former design was preferredbecause of the lesser quantity of cementrequired, 90 casks per structure instead of 160,and the quality of work could more easily bechecked (1). These concrete constructions wereconsidered to be technological advances overthe textbook field defences that engineerofficers had studied and knew from thestandard Instruction in Military Engineeringwhich dated from 1888 (2).

The concrete and cement industries inBritain were meanwhile becoming moreestablished. In 1904 the first standard forPortland cement, B.S. 12, was issued and in

1908 The Concrete Institute, later to becomethe Institution of Structural Engineers, wasformed.

Developments During Warfare.During July and early August 1914 the

armies of Germany, Austria-Hungary, Russiaand France declared war amongst themselvesand mobilised their armies: Britain was notinvolved and was ready to stay that way. It wasthe intention of Germany to conquer Francewithin 30 days and to this end they invadedBelgium, the neutrality of which had beenguaranteed by the belligerents and Britain. Themain defences of Belgium were rings of forts,recently constructed using thick layers ofreinforced concrete, around the cities of Liégeand Namur. The Germans had planned for thedestruction of these forts and used speciallydesigned very heavy artillery, 42cm mortarsnamed Big Bertha after the wife of themanufacturer, Krupps. The concrete of theforts crumbled easily; investigative reports afterthe war blamed the failure largely on very lowcement contents (250kg/m3, instead of400kg/m3 used elsewhere, was specified butcontractors used lower values) and poorconstruction standards (3).

Following the invasion of Belgium, Britaindeclared war on Germany on 4th August 1914and the British Expeditionary Force, withaccompanying Field Companies of RoyalEngineers, crossed the Channel within a fewdays. At about 7.00am on 22nd August anadvanced cavalry patrol of the Royal IrishDragoon Guards came across a patrol of theGerman 4th Kuirassiers; Corporal E. Thomasfired the first shots of the British Army on thecontinent for almost 100 years and the cavalrycharged with swords raised. At this stage itwas assumed that the war would be a shortone of a mobile nature and little or no thoughtwas given to the likelihood of the need forfixed defences.

Through the rest of 1914 and early 1915a mobile land war was becoming less likely asstatic warfare set in and both sides dug lines oftrenches and artillery positions which ranbetween the Belgian coast and the Swissborder. A number of technological advanceswere made by both sides to try and break the

Figure 1. Detail of a still surviving early British concrete shelter built near Ypres,probably in 1916. Railway line has been used to form the roof joists and an iron farmgate (arrowed) has been used as reinforcement although this has separated the layersof concrete and therefore actually weakens the structure. The concrete mix includesbroken brick and over most of the structure shows little sign of compaction.

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deadlock - chlorine and mustard gasses,armoured landships (‘tanks’), amphibiouslanding craft for a British attack on the Belgiancoast, flame throwers and others (including theprotective steel helmet!) but neither was ableto break through the opposition’s defencelines. 1916 saw massed infantry attacks, suchas on the Somme and at Verdun, on stronglyheld enemy positions but machine guns andartillery denied any progress and resulted incountless losses on both sides. The Britishoffensive at Ypres and Passchendaele in thesummer of 1917, which came to typify theconditions as thousands died or disappeared inthe Flanders mud, marked a turning point inthe use of concrete for fixed defences. Up untilthen the British had made very little use ofpermanent shell-proof cover as politically andstrategically we were still on the offensive,whereas the Germans were on the defensive.British troops in the front line trenches weredenied defences which might have been seenas permanent as this was perceived asreducing offensive spirit. Concrete was seen asa perfect material for the situation by someRoyal Engineer officers but official backing fromArmy Commanders was not received and onlya very few structures were built before the endof 1917. Those which were built, by the localinitiative of some Engineer Companies, were ofvariable quality.

The Germans had spent the previous 2years planning, designing and constructingstrong shelters to protect troops, fieldheadquarters, artillery and machine gunshelters from British fire, using experience inconcrete technology gained from fortressbuilding coupled with means of overcomingthe unique practical problems of transportingand mixing large quantities of materials andproducing large reinforced concrete structureswithin 100 metres of the British front linetrenches. This was known to BritishIntelligence because they read of it in thenewspaper (the morning edition of the Dutchpaper Der Telegraaf, 20th October 1915 (4) butArmy planners preferred not to act on theinformation. It was known that large tonnagesof concrete aggregates for German defences(which were to be attacked by British troops)were being shipped up the Rhine, throughHolland and into Belgium. The BritishGovernment complained to the Dutch aboutthe passage through neutral territory, citingthe Hague Convention of 1907, but the Dutchdenied the trade, which meanwhile carried on

whilst numerous diplomatic memorandachanged hands between the two countries.Samples of aggregates, known to have beencarried across Holland, from captured Germanpositions were examined by geologists inLondon and confirmed as being fromNiedermendig rock, Linz and Erpel basalts,Odenwald quartz porphyry and Triassicgravels all from German sources. The situationbecame more complicated when, during theperiod of the Battle of Passchendaele, fightingwas reaching a crescendo and thousands ofBritish troops were being killed trying tocapture the concrete shelters, by now named“bunkers” and machine gun posts they hadnicknamed “pill boxes”. The following letterappeared in The Times in November 1917:

To the Editor of The Times

Having just read the protest of themembers of the Baltic ShippingExchange against the shipment ofcement to Holland, I have no doubtthat it will interest them and others toknow that the pillbox in which I nowwrite and which was built by theenemy is made of British cement. ThisI know by a small tin label which was dislodged from the middle of athick wall by a shell. The label wasembossed in English.

Nov. 14 R.P. Hewetson, Captain.

It was claimed that the German defenceshad been built using British Cement, sold toHolland for onward sale to the enemy. Thematter was debated in Parliament and furtherresearched: the tin seal referred to, whichidentified the source of the cement, was foundnot to be of Associated Portland Cement (themarketing organisation for many small Britishcement manufacturers) but Antwerp PortlandCement. The subsequent sale of cement toHolland was then banned.

The high quality of the Germanconstructions surprised the British: troops wereglad to have for the first time real protectionfrom artillery and many of the bunkers weredry and relatively comfortable after life in wettrenches. Following the battles around Ypresand its forerunner Messines the RoyalEngineers carried out detailed investigationsinto the concrete structures, their designs andmethods of construction and the newly foundability to withstand direct hits from artilleryshells (5) (6). Captured German documents were

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studied for information on structures andsome were tested to destruction by explosivesto determine their weakest and strongestelements. The British Army now conceded thatthe material did have a role to play and wasgiven official sanction. Supplies of cement andaggregates were made available to theEngineers, who began to make a determinedstudy of the properties of reinforced concrete.The German military engineers weremeanwhile perfecting their designs in planningand building the Siegfriedstellung (named afterSiegfried, the hero of Wagner’s opera, andcalled the Hindenburg Line by the British),which incorporated their most recent advancesin concrete technology and military scienceinto the most impregnable system of defencelines the world had then seen.

The Royal Engineers began a series oftests to find ways of overcoming someshortcomings of reinforced concreteconstruction. The problems of concussion fromexplosions, which could kill with no visiblesigns, were countered by the use of an outershell of concrete, to act as a burster layer, withan intervening air space to reduce concussion;the shattering of concrete was reduced by theincorporation of fine expanded steel mesh andthe poor setting of cement was found to bedue to plaster from the brick rubble which hadbeen used. Experiments were also carried outto determine which were the betteraggregates to use and what was the ideal mixdesign. Opinions varied but the volumetricratio of 1:2:4, or 1:6, became the most widelyused, and the thoroughness of completemixing and compaction was found to be ofimportance.

Courses on concrete construction forlower and non-commissioned officers, whowere to oversee construction, were started atthe Royal Engineers Training School which wasopened at Rouen. Lectures were held onaspects of materials, mixing and generalconcrete construction principles. The RoyalEngineers also opened The School ofInstruction at Le Parcq “For OfficersCommanding and Second-in-Command ofField Units” where officers underwent courseslasting 10 days on field engineering and“Enemy methods of field defences. Reinforcedconcrete with special reference to its use inshell proof structures.” (7)

Problems were experienced withconstruction within sight of German artillery

observation and range, and the setting ofcement during the extremely low temperaturesin the winter of 1917/18. Other problems suchas the storage of cement sacks and barrels inwet trenches were encountered and the rateof return of the containers lead to complaintsby the cement suppliers. It was found thattroops living in wet trenches had moreimmediate uses for wood and hessian.

Much consideration had been given topractical aspects of concrete construction inlocations within sight of German artillery andseveral systems of precast concrete beam andblock shell proof bunkers and pill boxes weredeveloped and factories opened. Theseprefabricated structures incorporatedpossibilities of variations in designs for differentpurposes, e.g. for pill boxes, field headquarters,field hospitals etc. The two largest factorieswere at Aire-sur-la-Lys and at Arques; a thirdfactory using the best elements of these twowas started at Engoudsent near Etaples buthostilities ceased before production began.The 2 factories obtained aggregates fromdifferent sources (crushed limestone fromMarquise, near Boulogne, and locally obtainedquaternary flint river gravel. Dune sand fromthe mouth of the River Somme was tried andrejected as being too fine and saline, alsorejected was porphyry from Brittany, slag fromBoulogne steel works and dolomiticlimestone). Cement was supplied in casks andstored in bulk. It came from a number ofmanufacturers in England such as West Kent,Wouldham, and Knight and Bevan on theThames estuary (later to be Blue Circle’s Bevanworks). Cement offered by the Frenchgovernment was refused on economic andpolitical grounds. A study of the differentqualities of the resultant concrete beams andblocks concluded that the gravel mixes werestronger than the soft limestone and were lessliable to damage in transit. Blocks werestrengthened with expanded metal mesh andthe beams were reinforced with 1/2” (12mm)steel bars. Due to the need for speed of mouldre-use a novel means of accelerating theconcrete hardening was developed: the use ofsteam to cure the units. Steam was injectedthrough the holes, at a pressure of 5-10 p.s.i.for 4-6 hours, in the newly cast units and the3-4 week strength was reached in 12 hours. Atit’s busiest period the Aire factory wasproducing over 7,000 wall blocks and 650 roofbeams per day.

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Figure 2. Isometric view of standard design for Pill Box, produced at Aire-sur-la-Lys in1918, with details of beams and blocks. Concrete volume is about 70m3. Connectingsteel rods acted as post-reinforcement.

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Both factories systems were similar in thatthe beams and blocks had holes and groovesso that steel reinforcing bars could be threadedthrough the units to provide a monolithicstructure. The original design was for a cementgrout to be poured from the top to flow downthe holes and around the steel bars but this didnot work due to the grout losing flow (thereare no records of admixtures being tried!) andthis was changed to the use of mortar layer bylayer. The design criteria included speed ofmanufacture, ease of transport from thefactory to the trenches (the requisite numberof beams and blocks were accompanied byreinforcing rods, bags of sand and casks ofcement together with instructions andcamouflage material for use during and afterconstruction) and the resistance to a direct hitby the main German heavy field artillery 5.9”shell. Samples were shipped to the RoyalArtillery firing range at Shoeburyness in Essexfor comparisons of the shell resistance of thecompleted structures to be made and tests oncompleted structures in France involved pointblank hits by Royal Artillery 18lb field guns.(Figure: 4)

Early in the war the Royal Engineers hadestablished a large camp and port atRichborough in Kent for the shipment of heavyarticles such as heavy artillery, horse feed,

armoured landships (tanks) etc and toconstruct and repair barges for use on theFrench waterways. The site was chosen as S.Pearsons & Sons, Contractors, had opened thesite to manufacture precast concrete units forthe construction of Dover Harbour for theAdmiralty between 1898 and 1908. Pearsonssited their concrete factory here because of theavailability of aggregates at the adjacentStonar gravel pit and a wharf was constructedto load the units onto barges to Dover.

To house the troops who worked there,who later numbered 14,000, the RoyalEngineers constructed barracks made fromhollow concrete blocks produced on a pressmade by Winget Ltd. Some of these buildingsare still in use as light industrial units.Thisconcrete factory was then used tomanufacture, in 1918, the Moir Pill Box whichhad been designed and patented by Sir ErnestMoir, Minister of Armaments.(*) This circulardesign for a machine gun crew consisted ofinterlocking high strength concrete blockssurmounted by a steel cupola with suspendedgun mounting and was supplied to R.E. fieldcompanies in France in kit form for assembly inthe battle zone.

Other inventions at Richborough duringthis period included towed lighters for the

Figure 3. A still surviving example of the Aire pattern. It can be seen that a direct hit bya German shell has dislodged some corner blocks and the rear wall has bulged,indicating that blocks have been moved by the explosion but have been held togetherby the steel rods.

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Figure 4. Destructive testing. These test walls, which still survive at Souchez in France,were constructed using in situ concrete and different types of concrete beams. Theywere fired at by field gun to compare shell resistance. The tests were carried out on themorning of December 18th 1917 and the results influenced British concreteconstructions for the rest of the war.

launch and collection of sea planes, the firstwelded ships hull ever built in Britain and in1918, the roll on/roll off train ferry so thatarmaments etc could be loaded onto trains attheir point of manufacture and off-loaded inFrance without handling (this was abandonedafter the war and re-invented in later years).

To oversee the various trials and testsbeing carried out and to ensure theinformation was properly used, to liaise withthe concrete factories and to inspect andmaintain standards of construction, a seniorRoyal Engineer officer was appointed as“Inspector of Concrete Defences”. One of hisduties was to liaise with Geological Sections ofthe Royal Engineers, who were advising theArmy on mine warfare, supply of road metalsand the provision of dug-outs for shelter, onthe local winning of aggregates for in situconcrete work(8). Additionally some R.E.companies were given specialist training inprecast and in situ methods.

*Footnote. Sir Ernest Moir, 1862-1933,was a civil engineer who had beenResident Engineer and involved in workson Forth Bridge, Dover Harbour,Blackwall Tunnel, Hudson River Tunnel inNew York, and was Chairman of theCommittee on New Methods of HouseConstruction. He was created a Baronetin 1916.

Although the British Army had gone towar with Germany in 1914 with very littleknowledge of concrete construction and analmost zero technology level, by the end of thewar in 1918 a very good understanding of thematerial had been reached and major stepsforward had been taken. A number of thetechnology developments, such as interlockingblocks, expanded metal reinforcement toreduce shattering and steam curing toaccelerate hardening, were to be forgottenuntil later years.

Technology Developments in Britain.

Prior to the war McAlpine and Sons, amajor civil engineering contractor to thegovernment, who had built up muchexperience in concrete construction, haddeveloped their “ferrolithic” concrete, whichwas very hard and durable, using crushed slagfrom open hearth steel furnaces and Portlandcement. Several large industrial contracts hadbeen carried out using this. They had takenout a licence for François Hennebique’s“Beton Armé” (armoured concrete) and jointlyformed the McAlpine-Hennebique Ferro-Concrete Co. Ltd to use patented“improvements in the construction of joists,girders and the like with cement strengthenedwith iron or the like”(9). They had also made an

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agreement with another Frenchman, EdmondCoignet, to use the Coignet System ofreinforcement. When war was declaredMcAlpine’s workforce was greatly reduced asabout 5,000 of the workforce joined the Army.This company was then awarded contracts tobuild hutting for the thousands of troopsneeding accommodation in France as well asarmament factories and aerodromes aroundBritain.

The expertise in reinforced concrete wasput to use by McAlpines when they openedthe National Concrete Slab Factory at Yate nearBristol in 1917. Wood had become a scarcecommodity due to the German U-Boatblockade in the Channel and the Companybegan to produce precast concrete slab huts,fence and telegraph poles, reinforced concretejoists and other items previously made ofwood. These were some of the earliest utilityitems made from this material. Thecontribution to the war effort was rewarded bythe King who, in 1918, conferred a Baronetcyon Robert McAlpine and the Companybecame known as Sir Robert McAlpine andSons.

Concrete technology was also expandedas a means of overcoming the U-Boatblockade. A plan was formulated in 1917 toconstruct a chain of forts across the Channel,linked by electric submarine mines. Alex Gibb,who had the Army rank of Colonel, and was tolater form Sir Alexander Gibb and Partners, wasassisted by James Rennie and they designedthe concrete forts which were to beconstructed in the harbour at Shoreham andthen floated out to sea and sunk into position.Each unit was 61metres high and weighedabout 10,000 tonnes; use was made of massconcrete and 50mm thick precast slabsreinforced with expanded metal mesh. Twoforts were completed with more underconstruction when the Armistice was declaredin November 1918: their intended use wasnow not necessary. One unit was floated outto sea and towed to the mouth of the Solentand sunk into place. It is still there, with theconcrete withstanding the environment, as anavigation aid and nowadays known as NabTower. The steel shortage during the war alsolead to interest in the use of concrete for boatbuilding and several vessel types resulted. Anumber of the boats constructed were laterused for other tasks: one tugboat of a fleet of12 constructed to tow coal barges around the

Tyne, the “Creteboom”, which had earlier beenoperated by the Concrete Shipping Company,can still be found in the mouth of the RiverMoy in Ireland where it was sunk in 1937 todivert the flow of the river.

References

1 BREVET-COLONEL E.H. BETHEL, DSO RE. TheBlockhouse System In The South African War.Professional Papers of the Royal Engineers.Occasional Series, Paper XII, 1904.

2. Instruction in Military Engineering. Vol. 1 (Part 1) Field Defences. HMSO. 1888

3. GENERAL BENOIT. La Fortification PermanentPendant La Guerre. Revue du Genie Militaire.1922

4. Parliamentary Report, 1918. Transit TrafficAcross Holland of Materials Susceptible ofEmployment As Military Supplies. HMSO 1918.

5. German Concrete Structures on MessinesRidge and the Effect of Shell Fire on Them.Engineer in Chief’s Fieldwork Notes No. 31.1917.

6. German Concrete Structures in the Area Northof Ypres, Captured in August, 1917, and theEffect of Shell Fire on Them. Engineer in Chief’sFieldwork Notes No. 43. 1917.

7. COLONEL G,H. ADDISON. Work of the RoyalEngineers in the European War, 1914-1918.Miscellaneous.1927.

8. Work in the Field Under the Engineer in Chief.Geological Work on the Western Front.Institution of Royal Engineers. 1922.

9. I.F. RUSSELL. Sir Robert McAlpine and Sons. TheEarly Years. Parthenon Publishing. 1988.

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ANNUAL CONVENTION SYMPOSIUM: PAPERS PRESENTED 2000

PAPER BY:

KEYNOTE ADDRESS Mr. C.A. BannonBEMBA, MIEI, MICTIrish Cement Ltd.

CONCRETE - SYNONYMOUS Dr. K. ShuttleworthWITH MODERN ARCHITECTURE Dip Arch (Dist), RIBA, HonDDes

Foster & Partners

CONCRETE DESIGN LIFE Professor E.A. Kay - BIRTH TO DEATH PhD, BSc, CEng, MICE

Halcrow International

NEW CONCRETE Mr. P. GoringFOR NEW SYSTEMS MSc, BSc(Hons), ACGI, CEng, MICE

John Doyle Group

SUSTAINABLE CONCRETE Professor Dr. J.M.J.M. BijenIN HOLLAND Intron

CONCRETE AND THE Dr. P.J. NixonRAW MATERIAL SUPPLIERS BSc, DIC, PhD, FICT

Building Research Establishment Ltd.

FUTURE CHALLENGES FOR Mr. P.M. Barber THE READY MIXED CONCRETE INDUSTRY MICE, MICT, FIQA

The Quality Scheme for Ready Mixed Concrete

PREFABRICATION IN CONCRETE Dr. H.P.J. Taylor- OPPORTUNITIES FOR PhD, BSc, FREng, FICE, FIStructECONCRETE TECHNOLOGY Tarmac Precast Concrete Ltd.

A major part of the ICT Annual Convention is the Technical Symposium, where guest speakerswho are eminent in their field present papers on their specialist subjects. Each year papers arelinked by a theme. The title of the 2000 Symposium was:

CONCRETE PERCEPTIONS - ENGINEERING CHALLENGES AND SOLUTIONS

Chairman: Professor Ravindra K. Dhir, OBE, BSc, PhD, CEng, MIMM, Hon FICT, FGS

Edited versions of the papers are given in the following pages. Some papers vary in writtenstyle notwithstanding limited editing.

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Mr Chairman, Mr President, Members ofthe Institute of Concrete Technology.

Thank you for your kind invitation to givethe Keynote Address at this MillenniumConvention of the Institute. I have taken yourinvitation to a Member from Ireland as arecognition of the growth of Institutemembership in my country and to themagnificent work of the Irish Concrete Societyand in particular Mr Seoirse Mac Craith inrunning three Advanced Concrete Technologycourses in Ireland over recent years inconjunction with the Institute.

Mr Chairman, the issues of the past andthe future come very much into focus at thistime as we turn a new millennium. What canwe learn from the past? What does the futurehold? Whither concrete as an engineeringmaterial in the third millennium?

The great Bard of this town Stratford gaveus two perspectives on the past and future -From Hamlet:

“Lord, we know what we are, but knownot what we may be”;

a rather negative perspective. And fromMacbeth:

“If you can look into the seeds of timeand say which grain will grow and which willnot......”

I prefer to take the more positiveperspective.

Can I offer some comments from west ofhere - from Ireland - and from east of here -from Brussels - which is having a growinginfluence on our business and where I havespent some time in the recent past.

In Ireland we have seen tremendouseconomic growth over the last 7 to 8 years.The “Celtic” Tiger is alive and well and showsno sign of reaching extinction. We have hadaverage GDP growth of 7.5% per annum inrecent years and this growth is expected tocontinue, albeit at a slower rate over the nextsix years or so. The housing sector, thoughsmall relative to the U.K., is fuelling the growthin cement and concrete sales and making upan infrastructural deficit has also been animportant driver. Cement sales are always a

good indicator of economic activity and asignificant change has occurred in the lastdecade.

The boom has not been without itsdifficulties and one of the significant gaps thathave emerged is that of a skills shortage. Ofparticular interest is the shortage of bricklayersand the difficulties that this brings in a countrywhere concrete masonry per head ofpopulation is probably higher than anywhereelse in Europe.

Non-concrete based solutions forcladding are gaining ground and consequentlya number of precast solutions are currentlyunder consideration. “Whole-building”solutions involving factory made concretecomponents will have to be looked at moreclosely in the future particularly in areas such ashousing. Such solutions have been frownedupon largely because of the inappropriate andsometimes socially unacceptable applicationsof thirty to forty years ago. However, withrelevant social engineering they must be a partof our future. Innovation will be the key.

Moving to a broader historical perspectiveI would like to make reference to a paper byProfessor Sean de Courcy an Honorary Fellowof this Institute and a man recognised as the“father” of Irish concrete practice through thelatter decades of the twentieth century. In hisseminal paper delivered to the Institution ofEngineers of Ireland in November last year on“Irish Structural Engineering in the SecondMillennium” Sean de Courcy highlighted fivedefining events of the last thousand years:

One thousand years ago dry stone workwas slowly giving way to bedded masonry andlime mortar was gaining ground.

We had the birth of structural analysis inthe seventeenth century as physicists andmathematicians joined architects, engineersand contractors in the design and buildprocess.

The third great event was the arrival ofstructural metal in the eighteenth century andof course it was in this part of the world that itall started in the establishment of theCoalbrookdale ironworks on the Severn in1709.

KEYNOTE ADDRESS

Mr. C.A. Bannon BEMBA, MIEI, MICT

Irish Cement Ltd.

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The nineteenth century brought the“Rediscovery of Concrete” led by the patentingof Portland cement in 1824.

The twentieth century brought theelectronic computer, which broadened thehorizons of building in all materials.

Mr Chairman, I suggest these definingmoments apply perhaps beyond our littleisland and would stand the test as definingmoments in most countries. However oneviews the past, the position of concrete in thehistory of structural engineering is safe as weenter the new millennium. But what of thefuture?

The development of concrete in the earlyyears of this new millennium in all aspects ofbuilding will only be guaranteed if we succeed,in my view, in combining the talents of all theplayers in the drama of designing and buildingin concrete. Engineering and Architecture haveparted company somewhat; specialistproducers and precasters have developed theirown craft. Materials have becomecomplicated. Regulations abound.

The principal of one of our mostinnovative precast concrete producers who isconstantly pushing out the boundaries of hismaterial - and his work includes an insurancebuilding in Leeds, the Public Records Office inKew and some magnificent polished concretework on a project at Charlotte Quay in Dublin

- told me recently that the most exciting thinghappening in his business at the moment wasthe quest for a greater understanding ofmaterials and for innovation coming frombuilders and developers.

Co-operation is the key to the future andto the development of innovative, creative and“tactile” concrete solutions which will beappreciated by and serve mankind in the thirdmillennium.

The late great Irish structural engineerPeter Rice, who came to London to work withOve Arup and was involved in the concrete ofthe Sydney Opera House, the steel of thePompidou Centre in Paris and the concrete ofthe Lloyds Building in London, in discussinghow engineers can contribute to the work ofarchitects, had this to say in his autobiography“An Engineer Imagines” - “The most powerfulway that an engineer can contribute to thework of architects is by exploring the nature ofmaterials and using that knowledge toproduce a special quality in the way materialsare used. Exploration and innovation are thekeys”.

Peter Rice hit the nail on the head.

The key to the future is a fundamentalunderstanding of our material by all players andcloser co-operation and understanding.

We will hear throughout this Conventionfrom all players. I hope they agree.

Interior view of the Oulart Monument

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A simple example from Ireland of whatthis understanding and co-operation canachieve is the Oulart Monument in CountyWexford - a battle memorial - which only fiveweeks ago was awarded a specialcommendation by the Irish Concrete SocietyAwards Jury.

I quote from the citation:

“The Oulart monument brings togetherart, architecture and engineering, to create avery special place of peace and poeticinspiration. The design is outstanding; it drawson the ancient megalithic burial mound ofNewgrange for its inspiration but usesconcrete, the material of our age rather thanstone. This is a sculpture that one can walkinside, the light creating a different experiencewith every visit. It is an outstanding example ofthe ability of concrete to create something thatno other material could. It is an exemplaryexample of a monument of our age”.

Turning now to the European Union. Thetentacles of Brussels now stretch to 15Member States. Thankfully the bureaucratshave lost interest in the straightness of thebanana and other such esoteric nonsenses butdevelopments there in relation to our industryneed to be watched carefully and influenced indetail.

There are two issues in my view relevantto the broad concrete industry - Standards andSustainability.

After a tortuous process we now havethe first harmonised European Standardsagreed under the Construction ProductsDirective - the Standards for Cement andCement Conformity.

One can perhaps argue that there is noneed for a European Concrete Standard andthankfully EN206 for concrete is now comingthrough as a Framework Standard. There willbe significant work to be done to transposethis Standard into national documents and themembers of the Institute will have a key role toplay in this process.

Many other raw materials and productstandards are in the course of development.There has been significant time spent on thiswork. We must ensure that this time has beenwell used by ensuring that only standardswhich add value to the producer-designer-client relationship are taken forward.

Practitioners in the industry have solvedmany of the intriguing issues of concrete

technology of recent years - alkali-silicareaction, concrete finishes off the form, mixdesign for durability.

When issues come to the fore in thefuture we should get together and solve themquickly and move on. We are not in thebusiness of the production of research theses,per se, but in pushing the boundaries of thepossibilities of our material.

One issue of great significance and whichis developing apace and is lead in manyrespects from Brussels is that of thesustainability of building materials.

This development is both a threat and anopportunity.

Work of fundamental importance to thedevelopment of our material and tomaintaining it as the primary material for allbuilding and civil engineering has begun tomeet the threat and ensure we can profit fromthe opportunity.

A European Project involving the cementindustry, the precast industry, the admixtureindustry, the readymix industry, the steelreinforcement industry and the aggregateindustry has just got underway to evaluate andtake forward the issues that need to beaddressed in progressing Life Cycle Inventoryand Life Cycle Assessment Work on Concreteas a Building Material. This work is offundamental importance to the future ofconcrete and I am delighted to see that we willbe hearing later from Professor Jan Bijen withwhom I have had some contact in Brussels andwhom I know is associated with this project.

In my experience, there is significantmisinformation in the system on theenvironmental performance of concrete and onsustainability issues in general. Hopefully thisproject will lay the foundations for an agreedapproach to the subject for the years ahead.

Mr Chairman, the future is bright, wehave learnt much from the past. I believe“Sustainability” is the key issue for the nextcentury and that closer co-operation andpartnership across all disciplines will ensure thecontinued development of our material. ThisInstitute will have a key role to play and I lookforward to it developing and expanding its roleon the international stage.

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ABSTRACT: Based upon a presentation givenby Dr. K. Shuttleworth

One of the best known and mostphotographed modern architectural concreteconstructions is the chapel at Ronchamp inFrance, Le Corbusier’s famous 1955 design. Ithas received much fame and acclaim;unfortunately Le Corbusier did not understandtechnology and there is little or no concrete inthe building, which is a steel frame with acoating of cement mortar render. Analternative approach is preferable; it isimportant to be honest in the way thatmaterials are used and concrete when it formspart of the structure should be visuallyapparent.

This alternative philosophy was used 25years ago in the planning and design of a largefinancial institution office block in the centre ofIpswich. The building, a waffle slab structurewithin a glass curtain wall, is shaped to followthe curves of the surrounding streets. Thedensity of the concrete is visually evident andpenetration of light into the building expressesthe use of concrete, this effect is especiallyevident at night. This expression of the use ofmaterials can be called Expressionism. Similarthought to the Romans, the honest use ofmaterials, was used for a later building atNimes. Concrete is the framework into whichthe building fits. The columns are exposed andleft raw, as stripped, and all blemishes arevisually apparent. This was followed by theIndependent Television Network offices inLondon 10 years ago. This joint venture of thePractice with Arup and O’Rourke is an in situframe with exposed waffles. One can enjoy thefact that the concrete is not perfect, with allblemishes, honeycombing and formworkmarks left raw to create a tension between therough concrete and the precise lines of theglazing and aluminium. All spaces are left clearand simple.

This clearness and simplicity is repeated ata contract nearing completion in Oxford. Thismodern architectural work in a conservativetown is low-key, honest and precise, withstaircases in precast concrete with in situ walls,

which are left as formed with no remedialwork. The columns and slabs show a strongorder of principle and simplicity and the lightand airy interior is calming and comfortable.Different buildings in other universities - theRobert Gordon in Aberdeen, where thecontrast of steel and raw concrete has beenknitted into the hillside, and a library inCambridge, repeat this theme of light and air.

The contrast of rough and raw, untreatedconcrete with the smooth lines of materialssuch as aluminium and glass expressesfundamental stability and this concept hasbeen used in the design of the author’s ownhouse in Wiltshire. Simple, flat concrete wallsleft as the formwork was stripped and glazedpanels curve around a central lawn to give anhonest use of both materials. The design ofbuildings in France, where the climate differsfrom Great Britain, has made use of thishonesty of the natural finish of untreatedconcrete. A school building comprises a falsesteel roof over concrete to provide perfectnatural air conditioning utilising the thermalmass of the concrete inner roof. The Museumof Prehistory was cast in situ in white concretewith no making-good after stripping anddominates the town. The interior is designed toreproduce the inside of a cave, being cool andvery dark with little natural light.

A recent design which has won a numberof awards is the American Air Museum at theImperial War Museum, Duxford. Built to houseand exhibit American military aircraft, thebuilding was constructed of precast concreteshells with in situ elements, which are leftuntreated to show construction blemishes. Thethermal mass of concrete is superior toalternatives such as steel and with a fullyglazed end wall it gives a cavernous quality inwhich the scale of the aircraft, somesuspended from the ceiling as though in flight,can be appreciated.

In conclusion, it is evident from a numberof recent successful and award-winningdesigns that concrete can play a major part inthe architect’s concept of the appearance of avisually pleasing structure. The material doesnot need to be hidden from sight or treated to

CONCRETE - SYNONYMOUS WITH MODERN ARCHITECTURE

Dr. K. Shuttleworth Dip Arch (Dist), RIBA, HonDDes

Foster & Partners

28

remove the blemishes and marks which arefrom its moulding and which give it character.This use of concrete by this Practice and theintended contrast between the raw, untreatedand as-formed finish and the clean and

geometric lines of glass and metal is an honeststatement of the use of the material as both astructural element and an architectural finish.

Figure 2. The entrance to the Museum. The tunnel-like entrance leads into a largevolume of space, into which the visitors emerge facing the nose of a B-52 Stratofortressbomber. The tunnel walls are of cast in situ concrete which have been left as-strippedand the formwork joints and concrete imperfections have not been treated.

Figure 1. The front of the American Air Museum at Duxford. The single-span concreteroof, partly earth covered, is the largest of its type in Europe. The 90m long fullyglazed facade gives an interior with a feeling of space in which the aircraft can beviewed.

29

TED KAYTed Kay is Chief Engineer Concrete

Technology with Halcrow Group Limited andVisiting Professor of Civil Engineering atQueen’s University Belfast. He has spent thewhole of his working life with consultantsincluding six years in the Middle East in the lateseventies and has specialised in theinvestigation and repair of concrete structures.

ABSTRACTThis paper describes many of the facets of

the Engineer’s role in the production of durableconcrete structures and in maintaining them ifthey should prove not to be durable. Examplesare given of the effects of different parameterson the cover required to achieve a given life ina marine structure, calculations of stresses dueto heat of hydration, development of aconcrete mix for use in a massive, unreinforcedfoundation, investigation of surface features onbored cast-in-place piles, cleaning of mouldgrowth on a major bridge in the Far East anddevelopment of documents for use instrengthening and repair.

KEYWORDSBored piles, Cleaning, Cover to

reinforcement, Durability, Heat of hydration,Mass concrete, Mould Growth, Repair, Surfacefeatures, Thermal Stress.

INTRODUCTIONAn Engineer who spends most of his

working day either looking at concretestructures or considering the behaviour ofconcrete in production or in service, will nevercease to be amazed at how concrete impingeson all aspects of modern life. It is used in thefoundations of our houses and also in thefloors and lintels. It is used in the roads,bridges, tunnels and railway sleepers, whichwe travel along to get to work. When we are atwork, it is present in the frames and floors ofthe buildings. Water is carried from concretedams and service reservoirs to our homes andoffices in concrete pipes and away again inconcrete sewers to treatment works where theaerators, settlement tanks and sludge

digestion tanks are all constructed fromconcrete. Power station generators andturbines are held on massive concretefoundations; their cooling towers andchimneys are thin shells of concrete.Substations and transformers are founded onconcrete. Transmission poles are precast fromconcrete. Food and other essential supplies aredelivered to our country on concrete runwaysor by ships alongside concrete piers and quays.If we become ill we are treated in hospitals,which are framed and clad in concrete;scanners and x-ray machines, which emitradiation, are shielded by high-densityconcrete.

It is difficult to imagine modern life or amodern infrastructure without concrete. TheEngineer can play an extremely important rolein the development and continuingserviceability of this infrastructure.

Stated simply, the Engineer’s role in theprocess of fostering the concrete infrastructureis to take the architects (or power engineer’s orsanitation engineer’s etc) basic scheme andmake it stand up and fulfil its function, not onlyon the first day, but for as long as the elementis required. In this respect, the Engineer maybecome involved at each significant stage inthe life of a concrete structure:

• design

• mix development

• construction

• maintenance

• repair

This paper will deal with each of theseaspects of the Engineer’s role, mainly bydescribing examples from the past year or so.

DURABILITY DESIGNThere are two main considerations in the

task of design of concrete structures - strengthand durability. Fortunately, there are extremelyfew instances where concrete structures orcomponents fail because of lack of strength.The design processes are standardised; qualitycontrol procedures on concrete materials andproduction result in very small probability oflow strength concrete being used in the works.

CONCRETE DESIGN LIFE - BIRTH TO DEATH

Professor E.A. Kay PhD, BSc, CEng, MICE

Halcrow Group Ltd.

30

Unsatisfactory performance because of lack ofdurability is a much more common problemboth nationally and internationally. TheEngineer’s role is frequently to provide durabledesigns or to deal with the consequenceswhen durability has not been achieved.

With the publication of CP110(1)

in 1972,durability design of concrete building structuresin Britain also became standardised andrelatively straightforward. The process was toassess the exposure condition for all or differentareas of the structure and assign them to oneof several simply-described categories. Thestandard laid down the grade of concrete,water-cement ratio, cement content andconcrete cover to reinforcement required toprovide durability in each exposure class.

This approach was later mirrored instandards for other types and uses of structuree.g. bridges and was also adopted in othercountries in Europe and further afield. Thereare several anomalies in this manner of dealingwith durability:

1. The basic assumption thatstructures of a particular type are allrequired to have the same life

2. Different degrees of protectionafforded by different types ofcement are not recognised (exceptin the case of sulphate attack).

The second of these was not aconsideration when the original standardswere published, as the majority of concrete atthat time was made from either ordinaryPortland cement or sulphate-resisting cement.Despite these anomalies, the durability ofstructures designed to these standards hasbeen satisfactory in the vast majority of cases.It is a simple and generally conservativeapproach which has the advantage that itpermits mixes in concrete production codes tobe aligned with the durability requirements ofthe design codes e.g. designated mixes in BS5328

(2).

There are generally two particularsituations where following the procedures inthe standards has not produced concretestructures with the required durability becauseof corrosion of reinforcement. With a great dealof generalisation and simplification, these are:

1. Buildings where members weredesigned with low cover (inaccordance with the requirementsof the standard) but where the

design cover was not achievedconsistently in practice.

2. Structures such as highway bridgesand those alongside or in the sea orin other saline environments, whichwere penetrated by chlorides.

The prescriptive approach has served uswell and with more stringent requirements forthe two cases mentioned above and withprovision for different design lives and theeffects of different cements, there is no reasonto believe that they should not continue toserve us well into the foreseeable future.Indeed, draft European and British Standardsare continuing down this route e.g. ENV 206

(3)

and BS 6349(4). In ENV 206, the various

deterioration processes are consideredseparately but the basic approach is the same.

Alternatives to the prescriptive approachto durability design are becoming availablewhere the appropriate deteriorationmechanism can be identified and the time toreach an unsatisfactory condition can beassessed. These approaches are applicable toparticularly stringent environmental conditionsor for particularly important or prestigiousstructures or where a particularly long life isrequired. They can also be used to assess theeffects of different strategies for achievingdurability, e.g. corrosion inhibitors, controlledpermeability formwork or assessing possibilityof a trade off between thickness of cover andquality of concrete. The deterioration process,which can most readily be dealt with in thismanner, is corrosion of reinforcement. In thecase of corrosion due to exposure in anenvironment involving chlorides the life of astructure can be considered to have fourdistinct phases:

- the time, early in the life of a structure,when a concentration of chloridesbuilds up at the concrete surface

- a period during which chlorides migratethrough the cover concrete andeventually reach a critical concentrationat the reinforcement sufficient todepassivate the steel and initiatecorrosion

- the time taken for development ofsufficient corrosion on the bar surface tocause cracking of the concrete

- the period for cracking to develop to anunacceptable stage when it becomesnecessary to repair the structure.

31

There are means of assessing the timetaken for each of these phases. TaywoodEngineering have completed a Partners inTechnology research project

(5)for DETR in which

they developed one such method andproduced a spreadsheet to carry out thenecessary calculations. The theoreticalassessments of the cover required to give 50and 100 year times to corrosion initiation forthe splash zone of a marine structure shown inTable 1 have been derived using theirspreadsheet AGEDDCA5. The effects ofdifferent types of cementitious materials,controlled permeability formwork and corrosioninhibiting admixtures have been included. Thevalues in the Table are for comparativepurposes only, to permit viable alternatives tobe costed and the most economical option tobe determined. They should not be useddirectly for design as they are based on onlyone part of the corrosion process and no“factors of safety” have been included.

THERMAL DESIGNAnother matter, which often arises during

design, particularly of massive sections, is theeffects of heat of hydration. In this case alsothere is information in standards andconsensus reports which can be applied to thevast majority of situations e.g. the tables in BS8007

(6)which give estimates of the range of

temperature rises for different thicknesses ofconstruction, different cement contents anddifferent types of formwork. However, there are

situations where it may be difficult to predictthe temperature build up and the stresses thatare a direct consequence, in a straightforwardway. This may be because the shape iscomplex or because of the sequence ormethod of construction e.g. slipforming. Usingmodern computer programmes, it is possible toestimate the build up of temperature with timeand also to assess the resulting stresses.

Figure 1 shows the temperature contoursfor a liftshaft in a high rise building.

Figure 2 shows the temperature historyfor two points, one at the surface and onesituated one metre from the surface. Graphsof this type are useful in that specificationsoften limit the temperature gradient over theoutside metre to 15 or 20˚C.

Figure 3 shows the variation of stress withtime for an internal point. The temperatureand stress calculations have been carried outusing Intron FEMMASSE software. It is possibleto review various options e.g. cement type,insulation, aggregate type, at the planningstage (including the use of cooling pipes ifrequired) to arrive at the most economicalsolution.

Required cover - (mm) to achieve design life

Cement type/protection measure 50 years 100 years

Portland cement 60 80

Portland cement/75%ggbs 40 50

Portland cement/25% pfa 50 60

Portland cement + CPF 50 70

Portland cement/75%ggbs + CPF 30 40

Portland cement/25% pfa + CPF 40 50

Portland cement + inhibitor 30 35

Portland cement/75%ggbs + inhibitor 30* 30*

Portland cement/25% pfa + inhibitor 30* 30*

*assessed values are less but this is the minimum value considered from a practical point of view.

Table 1. Theoretical assessments of cover to achieve short and long-term design livesfor different cement types, addition of corrosion inhibitor and controlled permeabilityformwork (CPF).

32

Figure 1: Hydration temperaturedistribution in a lift shaft at time of peaktemperature.

Figure 3: Variation of thermal stress withtime in a lift shaft.

Figure 2: Variation of hydrationtemperature with time for two points,separated by one metre, in a lift shaft.

CONCRETE MIXESThe Engineer has a role to play in the

development of appropriate concrete mixes,particularly those to be used in unusualcircumstances. The concrete mix developed forthe Low Level Refuelling Facility at DevonportRoyal Dockyard is an example of this

(7). The

foundation for the Low Level Refuelling Facilityrequired 11000 m3 of unreinforced concrete tobe poured underwater in a 46m x 27mcofferdam with a maximum depth of water of16m. This being a structure which came withinthe nuclear regulations, there was a need to beable to demonstrate that a uniform andhomogeneous block of concrete was beingproduced and exceptional levels of qualityassurance and quality control were alsorequired. Besides these factors, the principalconsiderations were:

- as the foundation was unreinforced,temperatures had to be controlled toreduce the probability of cracking

- the concrete had to be self-levelling andfree flowing to minimise the number oftremie locations required

- there was to be minimal laitance andwashout during pouring in order toreduce the likelihood of entrapment oflenses of weaker material

- to reduce the need for cleaning of thetop surface between pours and tocontrol escapes of material insuspension into the surrounding dockbasin.

In the face of this array of sometimesconflicting considerations, the normalspecification requirements for strength andwater:cement ratio almost took second place.However, for the record, the specificationrequired a strength of 40N/mm2 to be achievedat 56 days and a maximum water:cement ratioof 0.45. There were additional specificationrequirements for dynamic modulus and in situdensity.

The mix was developed during acomprehensive series of laboratory trials andfine tuned during trials at site including almostfull scale trials involving placing under water.The latter were essential in order to provide thenecessary degree of confidence in the plasticproperties of the mix itself and the proposedplacing procedures.

It was found possible to combinedifferent fractions of the local crushed

33

limestone aggregates to produce a smoothgrading commensurate with the requirementfor a free-flowing concrete. This included anadditional 6mm fraction not normally used forconcrete. The use of the local aggregateresulted in significant economies both in directmaterials costs (it was estimated that it wouldhave increased the cost by £100,000 to bring insupplies of aggregate from the next-nearestappropriate source) and also in the fact thatthe lower coefficient of thermal expansion oflimestone permitted deeper pours withoutgiving rise to unacceptable stresses duringcement hydration. Thermal issues were alsoaddressed by the inclusion of groundgranulated blastfurnace slag as 75% of thecement content. The laboratory and full scalesite trials were used to determine the optimumbalanced dosage of superplasticiser andcellulose-based anti-washout underwaterconcrete admixture.

Another aspect which had to beconsidered, both in mix design and in theplanning of the pour, was that the concretewould be placed through a number of tremies,in a grid pattern, which would not becontinuously fed. It is conventional practice tokeep tremie tubes and hoppers full of concreteduring a pour to minimise the inclusion ofwater and air. This was not possible in this casebecause of the area of the pour, the availableconcrete supply and the placing logistics.These potential problems were overcome,partly, in this case by the use of lay-flat tremiepipes. These pipes close under the externalwater pressure when there is no head ofconcrete inside and hence eliminate the needto keep the hopper topped up. However, itwas necessary to plan the pour, and inparticular to use the appropriate number oftremie locations, such that the concrete couldflow and completely fill the volume within thecofferdam but also such that there was not anunacceptably long delay between successivedeliveries to the same tremie. Clearly, the mixproperties were critical in developing the mosteconomic pour configuration. The concretehad to have good flow properties whendelivered and also had to retain workability sothat the following delivery to that hopper couldbe incorporated to achieve a homogeneousmass without any mechanical vibration.

At the same time as the trial mixes werebeing undertaken, a stringent quality regimewas developed so that a consistent product

could be obtained over the three-day period ofan individual pour.

The procedures involved:

• stockpiling and testing sufficientaggregate for the pour

• exclusive use of two batching plantsfor the duration of each pour

• independent inspectors located inthe control cabin at each batchingplant for the duration of each pourto sign off each load

• regular determinations of themoisture content of the aggregatesduring production of concrete andadjustment of the batch weightsand water addition accordingly

• comprehensive documentationrelating to the concrete,accompanying each load to site

• establishment of a testing stationbefore the entrance to the site toreceive, check and carry out tests oneach incoming load; thedocumentation was checked andthe concrete was tested for flow; incases of flow value slightly belowthe specified range, the flow wasimproved by a further period ofagitation in the mixer trucks; incases of lower flow, a furthercontrolled dose of superplasticiserwas added. No wagon waspermitted to enter the site until itsload was shown to be compliant inall respects

• temperature monitoring of theconcrete within the pour bythermocouples

• monitoring of length of timebetween successive concretedeliveries to individual tremies

• a coring programme to check in situproperties, the integrity of individualpours and the joints between pours.

The concrete engineers worked closelywith the construction team on most aspects ofthe planning as the concrete properties hadsuch a great influence on the choice of placingequipment, method of delivery from the trucksto final position in the works and the overallsuccess or failure of the project. The finalconfiguration adopted was to feed concrete via

34

two static pumps each delivering to anarticulated placing boom. Each boom servedtwelve tremie locations in turn. The tremieswere situated on a 7.75m x 6.87m grid patternand there was always a mobile pump inreserve.

CONSTRUCTION DEFECTS The concrete engineer is often contacted

when there are unexpected events duringconstruction on site. An example of this wasthe construction of a contiguous bored pileretaining wall in the south of England. Thepiles were installed under bentonite in clay,with few apparent problems. However, whenthe piles were excavated on one side to form acutting, some unexpected features wereobserved. On some piles there was a gridpattern of vertical and horizontal lines onsections of the uncased length of pile near thebottom of the excavation. The lines on thesurface were at similar centres to thereinforcement. Some cores were taken but didnot reveal much other than that the concretewas of good quality except for a very shallow (2or 3 mm) surface zone. Several windows were

cut on the pile surface to the depth of thereinforcement and these revealed somebentonite inclusions in the concrete. Theseinclusions were principally around thehorizontal bars but also within the concrete ina thin vertical vein alongside some of the bars.

From purely visual observations of thesurface features and the windows it wassurmised that a probable cause of the surfacefeatures was that the concrete, delivered bytremie down the middle of the pile, had beenunable to flow freely between the bars and intothe gap between the cage and the pile wall. Adifferential head had built up between theinside of the cage and the outside. When thedifferential head was sufficiently great toovercome the viscosity of the concrete, theconcrete had extruded through the cageresulting in the grid pattern on the concretesurface as shown in Figures 4 and 5. This waslater found to be the case by carrying out fullscale trials with down-the-hole cameras andvideo cameras. It was also found that thedifferential head problem could be substantiallyreduced by increasing the flow value from550mm to 600mm.

Figure 4: Vertical and horizontal sections through pile showing extrusion of concretethrough reinforcing cage.

35

MAINTENANCEConcrete structures are rarely maintained

(as opposed to repaired). However, onesituation where maintenance becamenecessary was the Tsing Ma and Kap Shui Munbridges in Hong Kong. These two bridges formpart of the Lantau Fixed Crossing which carrieshighway and railway traffic from the city to thenew airport at Chek Lap Kok. The highway ison the top deck with the railway at lower level.There are also two typhoon-protected highwaylanes on the lower deck. The Tsing Ma Bridgeis a suspension bridge with a main span of1377m. Kap Shui Mun Bridge is cable-stayedwith a main span of 430m. Both bridges haveprominent cable-support towers, which are200m high in the case of Tsing Ma Bridge and150m high in the case of Kap Shui Mun. Thebridges were opened to traffic in 1997 but thetowers had been completed in 1995.

By 1998, parts of the surfaces of thetowers had become disfigured by theappearance of dark stains. The surface stainswere particularly noticeable on the verticalfaces of the cross girders but they werediscovered to be widespread on other surfaces.When seen from a distance the stains lookedlike large patches of black discoloration.However, when seen close up they were foundto consist of individual round spots of typically2 to 3mm diameter. Although such staining isprevalent on many concrete structures in HongKong, these are prominent structures on aprestigious development; the appearance ofthe structures is of prime importance and thesurface staining was considered to beunacceptable. A study into methods ofcleaning was commissioned in the latter half of1998.

It was found that the stains had beencaused by mould growths (a type of fungus) onthe surface

(8). The hot humid environment in

Hong Kong is ideal for the development ofthese organisms. Cleaning of structurescolonised by mould growths is usuallyundertaken by low pressure spraying with abiocide followed up by jet washing after themould growths have been killed. Mouldgrowths need moisture to survive and multiplyand so application of a surface treatment torepel water can prolong the time until cleaningbecomes necessary in the future. In the caseof these bridges, the surface treatment wasnot permitted to change the appearance of the

structure or lead in itself to a maintenancecommitment.

In this case there were some practicalconsiderations which had a considerable effecton the chosen method of treatment. The onlypractical and economically viable means ofaccess to carry out the work was by cradle.This being the case, it was not consideredpossible to undertake the work at night whenthe traffic flows were such that all vehiclesusing the bridges could have been diverted tothe lower deck. It was therefore necessary tocarry out the work during the day with thebridges fully open to traffic. Minimisingsplashdown of cleaning fluid and surfacetreatment material was also of primeimportance. Because labour and access costsconstituted such a large proportion of the totalcost of the work, and because the work wasbeing carried out to a strict budget, it wasnecessary to reduce the number of operationsat each location to the absolute minimum. Itwas therefore decided to restrict the cleaningoperation to one jet washing only followed bysurface treatment.

The obvious choice for surface treatmentmaterial was silane or siloxane. However, mostmanufacturers of silane recommend at leasttwo coats. There would be a danger ofwindblown spray from application ofconventional silanes. Although it was notthought that silane would damage vehicles orother parts of the bridge itself, it wasconsidered best that this was avoided. Thisbeing the case, a silane paste was chosen.Paste can be applied by spray but is of a gel-likeconsistency. The paste remains on the surfacefor a short period but gradually breaks down asthe material is absorbed. Because the materialremains on the surface for a short period, thereis a better chance for the silane to be absorbedand hence only one coat is required.

The weather during the cleaning wascritical because a dry surface was required topromote absorption. The windy season had tobe avoided to minimise cradle downtime. Itwas therefore decided to restrict the work tothe period between September and Marchwhen weather conditions are usually mostfavourable. Before and as part of the contract,trials were carried out to determine jet size andpressure for effective cleaning of the concretesurface without damage and to determine theoptimum application rate for silane paste.

36

STRENGTHENING AND REPAIRThe Engineer has a major role to play in

the strengthening and repair of concretestructures although his role has been usurpedto a certain extent by testing houses and evenquantity surveyors. The concrete engineer canplay an important part in:

• preliminary inspection

• design of testing programme

• evaluation of results of testing

• development of strengthening orrepair proposals

• quality control during execution ofthe work.

Until recently, there were few standardsor consensus reports to assist the Engineer inthese tasks. However, CEN is in the process ofpublishing a series of standards on tests forrepair materials and standards on repairprinciples

(9)and execution of repair works

(10)have

already been published. The Concrete Societywill shortly publish a Technical Report

(11)on

determining the cause of defects in concretestructures. This document will also outlinerepair and protection measures. A TechnicalReport on strengthening concrete structuresusing fibre composites

(12)is at an advanced

stage of preparation.

CONCLUSIONThis paper has set out to show the many

facets of the Engineer’s role at all stages in thelife of a concrete structure from concreteproduction to repair and strengthening. Justas it is difficult to imagine a moderninfrastructure without concrete, it would bedifficult to imagine concrete without asignificant contribution from the Engineer.

REFERENCES

1. BRITISH STANDARDS INSTITUTION, CP 110The structural use of concrete, BritishStandards Institution, London, 1972.

2. BRITISH STANDARDS INSTITUTION, BS 5328Concrete Part 1, Guide to specifying concrete,British Standards Institution, London, 1997.

3. BRITISH STANDARDS INSTITUTION, DD ENV206 Concrete. Performance, production,placing and compliance, British StandardsInstitution, London, 1992.

4. BRITISH STANDARDS INSTITUTION, BS 6349Maritime Structures Part 1 General criteria,British Standards Institution, London, 1984 (incourse of revision).

5. BAMFORTH P B, Guidance For the selection ofmeasures for enhancing reinforced concretedurability - a predictive model for chlorideinduced corrosion and its use in definingservice life, Department of the EnvironmentPartners in Technology Programme, ContractZCI 39/3/376(cc967). To be published by theConcrete Society (with revised title), London,2000.

6. BRITISH STANDARDS INSTITUTION, BS 8007Design of concrete structures for retainingaqueous liquids, British Standards Institution,London, 1987.

7. WILLIAMS R and CULLEN D, Devonport RoyalDockyard, Concrete, 1999, September, pp 38 -40.

8. KAY EA and HUNTER C, Cleaning off mould,Concrete Engineering International, June/July1999, pp 44 - 46.

9. BRITISH STANDARDS INSTITUTION, DD ENV1504 Products and systems for the protectionand repair of concrete structures - Definitions,requirements, quality control and evaluationof conformity - Part 9: General principles forthe use of products and systems, BritishStandards Institution, London, 1997.

10. BRITISH STANDARDS INSTITUTION, DD ENV1504 Products and systems for the protectionand repair of concrete structures - Definitions,requirements, quality control and evaluationof conformity - Part 10: Site application ofproducts and systems and quality control ofthe works, British Standards Institution,London, 2000.

11. CONCRETE SOCIETY, Diagnosis ofdeterioration in concrete structures, TechnicalReport, The Concrete Society, London, 2000.

12. CONCRETE SOCIETY, Design guidance forstrengthening concrete structures using fibrecomposite materials, The Concrete Society,London, due for publication autumn 2000.

37

ABSTRACT:The Egan Report "Rethinking

Construction" concluded that the industry didnot need to review what it does and do itbetter but to do it entirely differently. This paperlooks at the changes in concrete constructionand how a specialist concrete contractor cancontribute to the improvements and benefitfrom achievements. On certain projectsconcrete construction is already movingforward with the introduction of an integratedapproach, skills training, minimization of waste,appropriate use of information technology,supply chain management and innovation inprocesses.

INTRODUCTIONDevelopments in concrete technology

and methods enable specialist concretecontractors to carry out their works differentlyto methods employed ten years ago. Therange of equipment available andmanufacturing processes are resulting in achange of emphasis in the balance of resourcesand labour skills required at site.

Demographic changes, increasingconcerns relating to skill levels in the industry,employment and safety legislation haveaffected the cost and approach toemployment.

The concrete contractors have developedfrom domestic labour and plant sub-contractors serving the needs of maincontractors to specialist contractors withcontracts direct with the Client. The concretecontractors have a trade association inConstruct and special status membership inthe Concrete Society. They contribute toworking parties and steering committees todevelop the industry, the National StructuralConcrete Specification for BuildingConstruction has been launched to provide anindustry standard. They undertake and financeuniversity research into methods forrationalizing construction and providingbenefits to clients.

Many of the initiatives concluded in theEgan Report already have some inertia in the

concrete field; this paper investigates how thisinertia can be turned into momentum.

CONCRETE DEVELOPMENTSProprietary formwork systems were

introduced into UK construction in the late1980s. Many of the systems manufactured inthe USA and Europe did not comply with UKHealth and Safety legislation, were not readilyavailable in sufficient quantity and requiredfurther development. However, the late 1990ssaw improvements in safety and quality and arapid increase in the use of systems.

The systems replace traditional timberand plywood formwork built on site. They areavailable for purchase or hire and each schemecan be developed using an integratedcomputer design taking the consultant'sdesign information in digital format andproviding a scheme-specific design. This designcan be tailored to suit the contractor's availablestock with additional hired items. The systemscan be re-used and refurbished to minimiseconstruction waste. Systems can belightweight and man handled, joining adjacentpanels with clamps to provide a rapidturnaround of formwork. The robust nature ofthe frames and ability to replace plywoodfacing ensures a consistent quality and regular

NEW CONCRETE FOR NEW SYSTEMS

Mr. P GORING MSc, BSc (Hons), ACGI, CEng, MICE

John Doyle Group

Table forms being placed into position.

38

surface finish. Recently the quality of single-usecardboard tubes provides a viable alternative tosteel shutters.

Similarly, proprietary falsework systemshave replaced traditional tube and fittings.Initially, designs were based on tubes withwelded fittings; these designs have now beenreplaced with lightweight aluminium systemswith high leg loads. They provide a reducednumber of components resulting in rapid cycletimes for floors. The systems can provide safeaccess for operatives and can be assembled intables for rapid repeats of floors.

Small elements of reinforcement in beamsand columns have been prefabricated either onor off site for several years. Significant researchhas been carried out into the rationalisation ofreinforcement design; one conclusion is thatthe process and overall cost can be reduced byminimising the number of loose reinforcementbar marks to be fixed at site. Under factorymanufacturing conditions, using finite elementanalysis, reinforcement can be typically reducedby 20-40% for prefabricated floorreinforcement. This reduces labourdependency and also minimises poor cycletimes.

The ready mix concrete companies haveinvested considerably in developing concretemix designs to suit site conditions. As aconsequence, pump and skip mixes areproduced using blended cements whereappropriate. There is an increased use ofadmixtures to act as water reducing agents,plasticisers and to produce watertight andother special concretes. This has generallyresulted in contractors with sufficientknowledge being able to increase pour sizesand reduce striking times for falsework andformwork.

Specification restrictions imposed on thesize and heights of pours are now reviewed toconsider restraints, early age cracking, thermalproperties of the mix, water/cement ratio andthe curing regime. Similarly, falsework strikingtimes are considered in best practice guidesdeveloped by research from the EuropeanConcrete Building Project (ECBP) at Cardington.Various methods can now be adopted at siteto determine the strength of cast concreteincluding temperature matched-curing ofcubes, temperature measurements and pullout tests. At the ECBP it was found thatstriking was possible after 19 hours - aconsiderable improvement on the formerstandard period of 14 days.

A more radical development in concretemix design is Self Compacting Concrete. This isconcrete that is able to flow under self weight,without segregation and without blocking onreinforcement. The concrete provides a densestructural concrete without any mechanicalvibration required for compaction. Thetechnique has been widely used in Japan andEurope with a limited number of applications inthe United Kingdom.

It has the advantage of eliminating noisefrom the work place and therefore provides asafe working environment. There is animproved surface finish and the cohesivenature of the material reduces grout loss. As aresult of these improvements a consistentsurface finish results in a reduction in making-good costs. Presently the mixes have apremium of around £20/m3 over conventionalconcrete and are only used where the methodof placing is expensive i.e. in densereinforcement and complex sections. However,there are cost benefits in formwork costs,surface finishing and making good, which willprovide net cost reductions.

Slab reinforcement using banded bars.

Workability tests on Self CompactingConcrete.

39

In some circumstances post-tensioning ofslabs can provide a cost-effective alternative toreinforced concrete building construction. Theuse of post-tensioning reduces depth ofsection, reinforcement requirements andprovides cost savings. The post-tensioned slabsare genuinely cost effective where spans aregreater than the standard 9m grid.

CHANGE OF EMPHASISTo address the recommendations of the

Egan Report it has been recognised that therewere five key drivers to achieve the changesrequired. These are committed leadership,focus on the customer, integrating the process,quality driven agenda and commitment topeople.

All construction contracts have four basicparameters: cost, time, quality and safety. Allbids are considered against these. Presently,the emphasis is almost always exclusivelybased on the tender costing, with importanceplaced on the programme duration and a lesserconsideration given to quality and safetyprocedures adopted.

The true value of the bid is actually amuch more balanced comparison of thesefactors. The cheapest initial tender will notnecessarily produce the bid with the cheapestout-turn costs. The Client would prefer costand programme certainty when entering into acontract. Experience indicates that this isachieved where the process is more integrated:

SPECIALIST CONTRACTORSTraditionally, particularly in the main

contract form of contracting, there has beenan adversarial culture leading to disputes andconflict. This resulted in poor relationships andlack of trust between main contractors andsub-contractors. The role of the sub-contractorneed not also be subordinate or submissive.

Several constraints are imposed on specialistcontractors, in particular:

- unrealistic contract programmes

- undue emphasis on cost rather than theother basic elements of constructioncontracts as outlined above

- inappropriate allocation of constructionrisks through the contract conditions

- poor definition of the contract scope; in particular the client's needs

- lack of clear communication betweenthe parties.

Delays to release of information resultingin disruption on site. The recovery of costs fordelays and disruption through the contract areinevitably emotive, can often be intangible andemploy a significant resource to justify claims.

Most specialist contractors, in contrastwith the majority of traditional maincontractors, have a higher proportion ofdirectly employed workforce. They tend to betrained in their particular trade and manyalready hold Construction Skills CertificationScheme (CSCS) cards. The management isexperienced within their particular speciality,more so than general contractors anddesigners, and therefore are able to offer aparticular insight into the construction process.

Specialists have experience of using theproducts and would be able to advise onappropriate applications. There may also beparticular relationships between the supplier of

the specified or similarproduct that may proveto be commerciallyadvantageous to theproject.

SUPPLY CHAIN MANAGEMENTThe general complexityand diversity of theconstruction processlends itself to an

integrated approach utilising the combinedtalents of architects, consulting engineers,contractors, specialist contractors, suppliersand quantity surveyors. This involves crossingtraditional boundaries to reduce thefragmented nature of the design process. Earlyinvolvement of specialist contractors willimprove the release and quality of designinformation, minimising the risk of significant

40

costly design changes during the constructionphase. Critical lead times can be identified andthe design process scheduled around thesedates.

Construction time savings can beachieved by integrating the design andconstruction process rather than attempting tocondense the construction period followingcompletion of the full scheme design.

The method of procurement is largelybeyond the scope of this paper, howeverestablishing relationships with specialists maylead to procurement of a range of projectsrather than individual schemes which couldresult in economies of scale to benefit allparties. Similarly, formal and informalpartnering arrangements could be established,developing interpersonal relationships andexchange of information between parties.

IMPLEMENTING CHANGETo implement these changes and

advance the industry to levels envisaged by theEgan Report requires

- Committed Management from allparties from Client and hisrepresentatives through all suppliers inthe supply chain

- Minimise Waste, this is not just physicalbut also intellectual waste and theduplication of work or unnecessary useof designers' time. Integrating theproject process reduces both.

- Manufactured Products improveconstruction time and quality, whichalso produce cost benefits

- Supply Chain Management integratingthe process and providing benefits to allparties to the supply chain

- Customer Focus, generally companiesconcentrate on satisfying the needs ofthe next employer in the chain ratherthan the ultimate customer.

Branded Products could provide solutionswhere buildings could be manufactured usingpre-engineered components minimising theamount of bespoke design.

Companies that embrace change willmake better profits.

Column encasement.

41

ABSTRACT: Based upon a presentation givenby Dr. J.M.J.M. Bijen

Professor Jan Bijen of the University ofDelft stated that already a third of all concretein Holland is recycled into road baseconstruction.

A new building law comes into force inHolland in 2002. It is based upon a systematiclife cycle assessment that measures the effectof any product, or whole building fromquarrying, to demolition and recycling. Thenew law will make mandatory thedetermination of an environmental profile overthe lifetime of every new building.

Assessment of the environmental impactof concrete was also explained. It can have avery long service life indeed, which reduces theimpact, but cement is the dominant factor inthe profile. Blended cements have 30 - 80 % ofthe impact of Portland cement and already60% of the concrete placed in Holland usesPortland blastfurnace cement.

SUSTAINABLE CONCRETE IN HOLLAND

Professor Dr. J.M.J.M. Bijen

Intron

42

43

DR. P.J. NIXONDr. P.J. Nixon is a Technical Director of the

Centre for Concrete Construction, BRE Ltd. andan Honorary Fellow of the Institute. He chairsthe BSI Aggregates Committee and the CENAggregates for Concrete Committee. He leadsresearch into many aspects of the durability ofconcrete and concrete materials and has aparticular interest in service life design.

ABSTRACTThe paper considers the challenges facing

concrete in responding to the demands of themodern construction industry and thecontribution of the raw materials suppliers inmeeting these challenges.

It is concluded that the raw materialssuppliers are well placed to meet thesedemands and in particular are respondingpositively to the sustainability agenda. Theintroduction of European Standards is the mostimmediate issue and particularly in the case ofaggregates the EU Mandate introduces somedifficulties. Innovation is most likely in tailoringspecific products for special uses. To maintainand enhance the position of concrete a qualitysystem for the whole concreting process isneeded. One essential component of this, arobust and usable system to ensure a servicelife appropriate to the needs of the structure, iswithin our grasp.

KEYWORDSConcrete, Cement, Aggregates,

Performance, Quality, Sustainability

INTRODUCTIONThe theme of today’s Symposium is

examining how concrete can respond to thedemands of the modern construction industryand today’s (tomorrow’s) world. My part inthis is to look at the role of the raw materialssuppliers.

I give this presentation, of course, fromthe perspective of a research organisation andnot from within the materials supply industryitself. Hopefully this will enable me to take anoverview and a broad perspective though

inevitably there will be detailed developmentsthat I am not privy to.

The way I shall approach this is to look atthe issues facing concrete as a material in thecoming years and then to examine how themain raw materials, cement, aggregates,admixtures and reinforcement, are respondingor are likely to respond to these.

THE ISSUESAbout a year ago I reviewed the future of

concrete as a construction material in akeynote paper for a conference at SheffieldUniversity

(1). The paper was reprinted in the

Millennium issue of Concrete.

Generically I saw the issues as:

- Performance

- Quality

- Sustainability.

Performance and quality are primarilyabout meeting the clients needs. Increasinglythe major clients are making it clear that whatthey really need is control of risk. Certainly theinitial cost must be right. More important,though, they do not want to be preventedfrom using a facility by unexpected needs formaintenance or premature failure. To the clientsignificant reduction in serviceability is just asimportant as the unlikely event of structuralcollapse. So performance encapsulates all theconcepts of service life by design and whole lifecosting while quality is about delivering thisperformance consistently.

Sustainability has a wider social context.The concern here is whether construction ismaking undue demands on resources and theenvironment which cannot be sustained formany generations. There are manyintertwined themes here including energy use,CO2 emissions, resource depletion, landscapedegradation and environmental effects such asnoise, dust and traffic.

THE FUTURE USE OF CONCRETEFrom a consideration of these issues I

concluded that the future of concreteconstruction looks something like this:

CONCRETE AND THE RAW MATERIAL SUPPLIERS

Dr. P.J. Nixon BSc, DIC, PhD, FICT

Building Research Establishment Ltd.

44

Portland cement based concrete willcontinue to be the major construction material.

In (say) the next decade coming to termswith, and perhaps refining, the new EuropeanCodes and

Standards will be a major concern.Additionally their position relative to ISO andASTM will have to be established. Producinggood national guidance will be a priority.

There are significant opportunities forinnovation in design, materials andconstruction practice.

Better meeting client needs forperformance and quality will be even moreimportant. This will need new partnershipsbetween clients and producers and a lessfragmented supply chain.

The time is ripe to attempt a synthesis ofthe building blocks of service life design into ausable system, with increasing use of theInternational Standard for service life designand specific models for predicting the servicelife of concrete.

Sustainability will become an even moreimportant theme and in some areas willbecome synonymous with service life design.Recycling/reuse could make an importantcontribution if integrated with the initial designprocess.

THE MATERIALS SUPPLIER’S RESPONSE

In the rest of this presentation I shall lookat how the materials supplier is likely to fit intothis future.

European StandardsComing to terms with the advent of

European Standards is the most immediatechallenge, particularly for the raw materialsuppliers. The ‘package’ of concrete materialsstandards is expected to be ready by December2003 when National Standards will bewithdrawn. I reviewed the position in depthtwo years ago at this Symposium

(2)and in

particular identified three key areas in whichEuropean Standards will differ fundamentallyfrom British Standards:

- legal status

- greater complexity

- need to demonstrate compliance.

Since that review the Standards forConcrete and Cement have been approved forformal voting, and the prEN for aggregates for

concrete, 12620, is undergoing 2nd CENEnquiry prior to formal vote. The content ofthe standards has not changed significantlysince my review. The main issue in theEuropean Standards Arena has been thefinalisation of the Mandates for Concrete andAggregates for Concrete and the issues whichthe responses to these have raised.

For concrete the key question has beenthe applicability of the Mandate itself becauseof the situation where ready-mixed concrete isclearly placed on the market but site mixed isnot. For the moment the decision of the EU isto restrict the Concrete Mandate to PrecastConcrete. EN206 will still of course apply to allconcrete. For aggregates the main new issueis the inclusion of performance characteristicsin the Mandate requiring freedom fromradioactivity, harmful substances andpolyaromatic hydrocarbons. It now seemsinevitable that EN 12620 will include arequirement that manufacturers must ensure,under the Initial Type testing, that aggregatesdo not emit radioactivity or contain suchharmful substances so as to exceed the limits inNational Regulations at the point of use. Howto ensure this and applicable limits will probablybe a question for National Applicationdocuments.

The Mandates also define the level ofattestation. For cements this is, as expected,1+ and will continue the present system ofthird party testing. For aggregates there is amore complicated situation where theMandate identifies the level of attestation as2+ or 4 depending on the criticality of use; thisto be decided by ‘National Bodies’. Thisobviously raises questions for cross bordertrading of aggregates.

The generality of concrete is, of course,outside the attestation system because of thenon-applicability of the Mandate.

An interesting situation is thespecification and testing for alkali silicareactivity. Because of the lack of consensusacross Europe this is currently, in both EN 206and EN 12620, deputed to NationalRegulations. However, the AggregateMandate identifies alkali reactivity as aperformance characteristic to be controlled.The practical importance of this can be judgedfrom the fact that a significant UK exportmarket in sea dredged aggregates is currentlythreatened by proposed Dutch Regulations onASR - free trade does need EuropeanStandards!

45

The overall effects of the introduction ofEuropean Standards are difficult to foresee. It isimportant to remember that their mainpurpose is removal of barriers to trade. Inachieving this they will undoubtedly introducemore complexity and may have the effect ofinhibiting innovation and constraining thespecifier who may, for example, wish to achieveextra high levels of durability for a very critical orlong design life structure.

InnovationI do not, in the foreseeable future, see

major changes in the main componentmaterials of concrete. The versatility andeconomy of Portland cement, and naturalaggregates, together with the increasing use ofpfa and slag, is such that these are almostcertainly going to remain the backbone of thesupply side. The advances will come in tailoringspecific products for special uses like specialistrepair products, the ‘Densit’ concrete glue andCompact Reinforced Composite concreteconsidered last year

(3)or high strength (and

perhaps ultra-high strength) concrete. Instructures which need to be highly durable weare likely to see an increasing use of morecorrosion resistant reinforcement, stainlesssteel or non-ferrous such as fibre reinforcedcomposites.

An area of current interest at BRE is theuse of alternative materials to minimise the riskof ASR where a working party convened by BREfrom within the industry is well advanced inpreparing guidance on the use of lithiumcompounds, metakaolin, microsilica and EN450 pfa. Such materials could find applicationwhere existing specification routes are difficultor where an exceptionally high level ofreassurance is needed in a particular structure.

Perhaps the one area where there isopportunity for general beneficialdevelopments is in the use of admixtures.These can find application in specifically tailoredcements or in site/ready mix concrete where arecent BRE review outlines the benefits thatcan be realised

(4). The drive to increase

construction efficiency is likely to lead toincreasing use of products such as selfcompacting concrete.

There is, of course, a lot of current interestin the use of recycled aggregates in concrete.Demonstration projects such as the BREEnvironmental Building have shown thepossibilities

(5)and the use of these products

was reviewed here two years ago by Collins(6).

More recently the use of such aggregates hasbeen given a sound basis of specification byBRE Digest 433

(7). The contribution to

aggregate resources that such aggregates canmake is considered further below.

Performance and Quality to meetclient needs

Quality will be dealt with more fully byPeter Barber. In many respects the qualitysystems to ensure that the raw materials areappropriate to client needs are now wellestablished in the UK. The missing link isensuring the quality of the whole concretingprocess. The most advanced development atpresent is the Registration Scheme for SpecialistConcrete Contractors (SpeCC) being developedunder PII. There is hope that this may be aspringboard for a wider scheme. These aredifficult areas in which to make progressbecause of strong commercial interests but ifconcrete is to improve its position and image ageneral improvement in quality is vital. Themost hopeful sign is the willingness of theconcrete industry to face up to and solve itsproblems together. The difference in attitudeover the recent thaumasite problems whereinterim guidance was quickly agreed and newresearch got under way compared with theearly days of ASR when defensive sectorialattitudes delayed resolution by a decade isremarkable.

New commercial alignments crossing theold aggregate/cement/ready mix boundariesmust also be helpful in providing the bestservice to the client.

Service Life and Whole Life CostsAs will be discussed below, specifying for

and obtaining a service life appropriate to theneeds of the structure is one of the keyelements in minimising whole life costs andachieving sustainable construction. Over thelast decade or so we have advanced a longway in our ability to do this

(8, 9, 10). We now have

a good understanding of the degradationmechanisms that can affect the long-termperformance of concrete in variousenvironments. Indeed in some areas, ASR forexample, we have been able to refine and insome cases relax our advice to make best useof the materials available to us

(11, 12). What is

now needed is to synthesise thisunderstanding into robust and usable systemsthat the engineer can use.

46

There are beginnings. The draftComplementary BS (BSCKTV) to EN 206 willgive concrete composition requirements for 50and 100 year service lives. The new BREDigests on Corrosion Protection

(13)introduce a

time element and probabilistic concepts. Therehas been valuable work within BSI

(14)and ISO

(15)

to establish the ground rules for service lifespecification, for example, to define a servicelife limit state. The Durability Audit

(16)developed

at BRE as a means of implementing the DETRDurability by Intent Strategy

(17)has developed

the key questions that need to be asked ateach stage of the Construction Process toensure durability for a specific lifetime. So thebuilding blocks are there and the time is ripe tointegrate our knowledge into a usable system.

SustainabilityEnvironmental issues in general are

considered by Professor Bijen. I would like tofocus on some issues specific to winning andprocessing minerals for construction.Construction is a major consumer of minerals,digging for example over 200 million tonnes ofaggregate per year, about 30% of which gointo concrete. This introduces severe tensionsin the rest of society who need the productsbut do not like the land use, transport etcinvolved. To counteract this the QuarryingIndustry has transformed its image onrestoration of workings and avoidance as far aspossible of noise and dust. Nevertheless thepressures continue and in response to thethreatened aggregate tax the QPA has offeredthe most comprehensive response ever in theshape of a thirty point plan, ‘The New Dealfrom the Aggregates Industry’

(18)which at an

estimated cost to the industry of £100 millionper annum offers environmental benefits ofover £150 million per annum to mitigate theimpacts of supplying construction aggregates.At the time of writing the Government’sresponse remains to be seen but this illustrateshow far both society and industry have nowmoved towards demanding and ensuring thatindustry are good neighbours.

A second area of major concern inrelation to minerals is resource depletion. Atone level there is an infinite supply of rockavailable to us. However, the supply oftechnically, economically and environmentallyacceptable materials can be very difficult insome areas. Netherlands and Belgium, forinstance, are increasingly importing aggregatesand within the UK there are economic areas

e.g. the South East and North West which areexcessively dependant on imports from otherareas. Brown

(19)has reviewed the possibilities

for using alternative and marginal aggregateswhile Collins

(20 - 22)has reported long term

practical assessments of the use of Jurassiclimestones, Magnesian limestones and poroussandstones in concrete. All of these studiesshow that technically acceptable concrete canbe made from a much wider range of materialsthan are in use at the present; the barriers aremore to do with economics, logistics andconcerns about risk than about technicalperformance.

There is a conflict therefore between thedemands of society to use the mostenvironmentally acceptable materials and theclient who wants guarantees of goodperformance and lower risk. New EuropeanStandards may help this conflict as in order toreduce barriers to trade they must include amuch wider range of materials includingrecycled and artificial materials and ensure thatthey give adequate performance. The secondgeneration of standards will, for example,include specific clauses to cover the use ofrecycled construction materials as aggregate.

Overall environmental concerns andsustainability are firmly on the agenda of theraw materials supplier, as shown by the currentwork of the Concrete Society EnvironmentalWorking Party and the BCA-led Partners inInnovation project, ‘Improving theenvironmental impacts of concrete’.

CONCLUSIONOverall the raw materials suppliers are

well placed to respond to the needs of the newcentury.

Coming to terms with EuropeanStandards is the most immediate challenge andparticularly in the case of aggregates the EUMandate is threatening to introduce somedifficult new issues.

The present suite of component materialsseem likely to remain the mainstay of concrete.Innovation will, however, increase constructionefficiency by tailoring specific products forspecial uses.

Quality systems for the raw materials arewell established; what is needed is a way ofensuring the quality and performance of thewhole concreting process.

A robust usable system to ensure a

47

service life appropriate to the needs of thestructure is within our grasp.

Raw materials suppliers are responding tothe Sustainability Agenda positively.

Perhaps the biggest change will be thatall of these issues; quality, service life designand sustainability will become assimilated asnormal parts of the design/procurementprocess.

REFERENCES

1. NIXON, P J. Concrete - Construction Materialfor the Next Millennium, Proceedings ofInternational Conference onInfrastructure Regeneration andRehabilitation, Sheffield, June 1999, pp 43-50.Reprinted in Concrete, Vol. 34, No. 1, January2000, pp 20-23.

2. NIXON, P J. Update on European Standardsfor Concrete and Concrete Materials.Presented at ICT Annual Symposium 1998 andreprinted in Yearbook 1998-1999, pp 53-58.

3. AARUP, B. Fibre reinforced high performanceconcrete for precast applications. Presented atICT Annual Symposium 1999 and reprinted inYearbook 1999-2000, pp 27-32.

4. RIDAL, J. P., GARVIN, S. L, AND DUNSTER, A.Water-reducing admixtures in concrete: anintroduction to their use, benefits andapplication. BRE Information PaperIP15/2000/CRC 2000.

5. HOBBS, G, AND COLLINS, R. Demonstrationof reuse and recycling of materials: BRE energyefficient office of the future. BRE InformationPaper IP 3/97. CRC 1997.

6. COLLINS, R J. Recycled Concrete -Specification and Control, Presented at ICTAnnual Symposium 1998 and reprinted inYearbook 1998-1999, pp 59-67.

7. RECYCLED AGGREGATES. BRE Digest 433,CRC November 1998.

8. ARCHITECTURAL INSTITUTE OF JAPAN.Principle Guide for Service Life Planning ofBuildings, 1993.

9. CONSTRUCTION AUDIT LTD. HAPMComponent Life Manual published by E & F NSpon, 1992.

10. BOURKE, K, AND DAVIES, H. Factors AffectingService Life Predictions of Buildings: adiscussion paper. BRE Laboratory Report 320,CRC Ltd, 1997.

11. ALKALI AGGREGATE REACTIONS INCONCRETE. BRE Digest 330, CRC 1999.

12. ALKALI-SILICA REACTION - minimising the riskto concrete, Guidance Notes and ModelSpecification Clauses. Concrete SocietyTechnical Note 30, 1999.

13. CORROSION OF STEEL IN CONCRETE. BREDigest 444, parts 1, 2, 3. CRC, February 2000.

14. BS HB 10141 Buildings - Service Life Planning,BSI, 1997.

15. ISO 15464-1 Buildings Service Life Planning.ISO, 1999.

16. MARSH, B K, AND NIXON, P J. AssumingPerformance of Concrete Structures through aDurability Audit. Concrete in the Service ofMankind, Dundee, June 1996, pp 49-59.

17. DURABILITY BY INTENT. Strategy for DOEProgramme on Durability of Concrete andReinforced Concrete. DOE ConstructionSponsorship Directorate, November 1994.

18. THE NEW DEAL FROM THE AGGREGATEINDUSTRY - a partnership proposal forenvironmental improvement. Quarry ProductsAssociation, July 1999.

19. BROWN, B V. Alternative and MarginalAggregate Sources, Proceedings ofConference, Concrete in the Service ofMankind. Dundee, June 1996, pp 471-484.

20. COLLINS, R J. Porous aggregates in concrete:Jurassic limestone. BRE Information Paper, IP2/86, CRC 1986.

21. COLLINS, R J. Magnesian limestoneaggregate in concrete. BRE Information Paper,IP 2/91, CRC 1991.

22. COLLINS, R J. Porous aggregates in concrete:sandstones from NW England. BREInformation Paper, IP 16/89, CRC 1989.

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49

FUTURE CHALLENGES FOR THE READY MIXED CONCRETE iNDUSTRY

Mr. P.M. Barber MICE, MICT, FIQA

The Quality Scheme for Ready Mixed Concrete

Mr. P.M. BARBERMr. P.M. Barber MICE, MICT, FIQA, is a civil

engineer by profession having spent hisformative years supervising the construction ofboth nuclear and coal fired power stations. Hismiddle career phase included work with majorcontractors and a period as a lecturer inconstruction materials. In 1974 he joinedBRMCA, the then trade association for theready-mixed concrete industry. In 1987 hewas appointed Manager of the Scheme forQSRMC and has to date been responsible forthe certification and confirmation of the qualityof 90% of the ready mixed concrete producedin the UK.

ABSTRACTThe paper reviews the progress made by

the ready mixed concrete industry in the 20thcentury in its quest for quality and looks atsome of the challenges that lie ahead for the21st. The BRMCA Authorisation Scheme wasthe first public statement of the industry’sintention to address quality issues. The TradeAssociations then went through a period ofrestructuring which saw the introduction of theBACMI Code. The first pan-industryindependent scheme was The Quality Schemefor Ready Mixed Concrete set up in 1984. Atthe time of gaining accreditation in 1987 thenew QSRMC Scheme embraced BS 5750, theforerunner of today’s ISO 9000 series of qualitystandards. ISO 9000 has now undergone areview of objectives and a major restructure.The document will be published in its new formin December 2000. The ready mixed concreteindustry in common with all other qualityassured companies now faces the challenge ofadopting and implementing the philosophycontained in this new Standard.

KEYWORDSConcrete, Quality, ISO 9000, QSRMC

THE GROWTH OF THE QUALITY ETHIC

In 1968 the ready mixed concreteindustry was growing rapidly, but site mixingwas still the norm and engineers liked the

control that this gave them at site level. Theindustry responded to this challenge bylaunching the British Ready Mixed ConcreteAssociation’s Authorisation Scheme. The newScheme set standards for the design of plantsand for their maintenance. Soon after an extrasection was introduced on a voluntary basis tocover quality control procedures; this sectionwas known as Section E.

Although there had been some ‘kitemark’ schemes in existence since the late1920s, the BRMCA Scheme was probably thefirst industry-wide scheme aimed at improvingstandards and was also one of the first productquality standards.

By 1974 there were some 750 plants inthe Scheme, about a third of which had SectionE status. BRMCA employed eight engineers tocarry out inspections of the plants and thequality control records.

With the change in structure of the TradeAssociations the BACMI code was established,which although being a largely self-policedcode, did make a major step forward in that allmembers were required to operate qualitycontrol procedures at all plants. 1984 saw theamalgamation of the two Trade AssociationSchemes into the new Quality Scheme forReady Mixed Concrete under the independentChairmanship of Professor Peter Stott.

At the same time Government began todevelop proposals for the accreditation ofindependent bodies offering certification andQSRMC quickly entered into discussions todetermine the mechanism to gain formalrecognition. Two major changes wererequired, firstly the introduction of a GoverningBoard representing the interests of all partiesconcerned with the product, and the secondrequirement was the adoption of the UK’squality standard BS 5750. Again the Industrysaw the long term benefits and QSRMC gainedits Accreditation in 1987.

In 1994 the BS 5750 concept wastransposed into an International Standard, ISO9000. This single Standard has outsold allother National and International Standards andis now adopted as the quality standardthroughout the world.

50

Similarly accreditation of CertificationBodies has grown into both a European andInternational activity and there is formalrecognition of accredited certificates across theworld.

The International Standard is of courseintended to provide a quality standard for allactivities and requires interpretation for eachindustry and product application. In 1995QSRMC launched its Quality and ProductConformity Regulations, which is anintegration of the industry best practice fordesign, production and control of concretewith the quality standard, probably the firsttruly integrated standard for any industry.

THE CHALLENGE FOR THE FUTURE

Once again the Standards makers havebeen at work and have concluded that thewhole series of quality standards require majorrevision to take on board a range of otherinitiatives such as total quality and elements ofthe investors in people concept.

The new documents are known as theISO 9000: 2000 series, with a target publicationdate of December 2000. This new documentrepresents an important contribution to riskand cost management. The InternationalBodies that oversee accreditation haveconcluded that all ISO 9000 certificatedcompanies world-wide should move across tothe new Standard within three years of itspublication.

The QSRMC Board has made acommitment to the adoption of the newStandard for the industry and to continue to bethe market leader.

WHAT ARE THE MAIN CHANGES?Under the current system there are three

separate Quality Standards against whichcompanies can be certified according to thenature of their business. ISO 9001 is theStandard that is used if the process involvesdesign, ISO 9002 if design is not involved andISO 9003 for final inspection and test only. Thisstructure has led to confusion in themarketplace and so the new Standard coversall aspects in the one document; ISO 9001.However the certifying body must identify onits certificates which clauses are not covered,should that be the case. Additionally wheredesign is involved in the process then that

activity must be covered by the certificate,which was often not the case in the past.

There is a new document, ISO 9000,which deals with the fundamentals andvocabulary and a new ISO 9004 which providesdetailed guidance on ISO 9001.

There are three main areas of change ofemphasis:

- the system to have a processstructure

- the role of management

- monitoring the effectiveness of thesystem.

THE PROCESS STRUCTUREThe new Standard recognises that the

operations of any company can be brokendown into a series of processes and sub-processes. These processes need to bedocumented. In reality this is what has alreadyhappened in the well organised companies,the documentation taking the form ofprocedures for each activity. In the QSRMCScheme the Regulations have had thisstructure since 1995:

- an overall system - Part 1

- contract review - Part 2

- purchase and control of materials- Part 3

- design - Part 4

- manufacturing equipment - Part 5

- control - Part 6.

and within each Part the necessaryprocedures have been listed, which are ofcourse the sub-procedures.

THE ROLE OF MANAGEMENTTwo sections of the new Standard are

allocated to management within which the keyroles are to:

- ensure that the organisation iscustomer focused

- ensure that adequate resources areavailable

- set an overall quality policy

- ensure that quality objectives are setfor each process and sub-process

- put in place a system of measuringand monitoring the effectiveness ofprocesses

51

- review the system in the light of theoutcome of measuring andmonitoring.

that is, to set up a system that throughassessment seeks to gain improvement againstset objectives which necessarily will include riskto the product and control of cost throughcontrol of waste and reworking.

MONITORING ANDMEASUREMENT OF PROCESSEFFECTIVENESS

The assessment of the effectiveness ofthe processes can be carried out in two ways:

- by making physical measurementsby testing

- by monitoring how well tasks arecompleted against expectations.

A set of test regimes and correctiveactions are already in place within Parts 3 and 6of the Regulations.

THE STRUCTURE OF THE NEWISO 9001: 2000 DOCUMENTS

The current ISO 9001 document has a 20-section structure, which in the new version iscondensed into 3 of the 4 new sections.

The first 3 are:

- management responsibility

- management of resources

- process realisation (making or doingthings).

Almost all the current content of theexisting document is retained in some form inthe new format.

The new fourth section deals withmeasuring effectiveness (improvement).

WILL MANUALS HAVE TO BEREDRAFTED?

The QSRMC Board has concluded thatthe Regulations should be restructured, i.e. thecontent of each of the existing Parts will bereassembled in the new four section layout. Itis expected that most companies will see abenefit in following the same route.

ISO 9001: 2000 identifies six specificprocedures that must be documented, but alsorequires that processes and sub-processes aredocumented together with the records thatwill need to be kept. Provided that currentprocedures are focused on a process structurelittle detailed redrafting of procedures will berequired, although a key new procedure is thatdealing with monitoring and measurement.What will be needed, if not already in place is aquality objective for each of these documentedprocesses and sub-processes.

WHAT ARE THE TIME SCALES?The International Body that oversees

accreditation has agreed that certificatesshould not be issued against the old Standardonce the new Standard has been in place forthree years. Thus the expected date for thecompletion of the changeover is December2003.

QSRMC intends to issue a transitionalversion of its Regulations on the same datethat the new Standard is published. Newapplicants to the Scheme will be able to workto the new Standard from that date andexisting companies will be able to move acrossas soon as they are ready. New ISO 9001:2000 certificates will only be issued whencompanies have fully demonstrated that theyconform to the new Standard.

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53

DR. HOWARD P.J. TAYLORDr Howard P J Taylor is Technical Director

of Tarmac Precast Concrete Limited. Hisresponsibility is for the engineering anddevelopment of a precast concretemanufacturer with interest in a very wide rangeof products and services.

ABSTRACT There is a new interest in prefabrication

which has come from the perceived need tomodernise the UK construction industry and tointroduce construction systems which useadvances introduced in manufacturing. Thischange has led to a better definition of therequirements of concrete to enable it to play itspart in changing the site into an assemblylocation. The paper reviews a number of verydifferent approaches to this challenge from thepoint of view of the development of concretetechnology. Foam concrete, fibre reinforcedconcrete, high strength concretes and selfcompacting concretes will be reviewed.

KEYWORDS:Prefabrication, Precast Concrete,

Concrete Technology, Foam, High Strength,Fibres, Self Compacting.

INTRODUCTIONConcrete used in factory-produced

prefabrication has a number of requirementsthat are different from site cast concrete whichvary according to the product type and themanufacturing process. It is universallyappreciated that prestressing by thepretensioning technique requires high earlystrengths whereas concretes for reinforcedproducts may need only modest earlystrengths for lifting. Concretes also require verydifferent plastic properties, ranging from verycohesive to flowable mixes.

Concrete technology has movedforwards dramatically in recent years and wenow have the opportunity to define propertiesrequired by products and production systemsand to satisfy these with an appropriate choice

of the raw material selection, mix design andplacing technique.

This paper introduces some examples ofrecent technology developments that showpromise in giving excellent solutions to somecommon prefabrication requirements. Each willbe covered in turn and related to the sector ofthe precast industry where it would be ofgreatest use.

HIGH STRENGTH CONCRETEHigh strength concrete requires some

discussion before it can be commented upon.The combination of high yield reinforcing steeland grade 40 concrete is adequate forreinforced concrete construction althoughsavings of space can be made if columns aremade of concretes that are significantlystronger.

Prestressed concrete made in factories isusually pretensioned and, if a daily mould use isto be maintained, concretes need a 12 - 18hour transfer strength of at least 40 N/mm2.With modern water reducing admixtures thisautomatically leads to a 28 day strength well inexcess of 60 N/mm2, often in the region of 70 -90 N/mm2. Higher strengths are possible andcharacteristic strengths of 100-120 N/mm2 canbe produced economically. High strengthconcretes can be characterised by aggregatefailure rather than failure of the cement matrixand thus do not have higher strengths in shearthan grades in the 60-70 N/mm2 region.

The use of concretes of strengths inexcess of 80 N/mm2 is therefore unlikely to finda mass market in prefabrication without furtherdevelopments to overcome these difficulties.

High strength concretes are of use in thetunnelling industry, a recent contract forexample was for a concrete shaft lining blockwhich was required to have a characteristicstrength of 140 N/mm2 and required the use ofgranite aggregate and micro silica in a speciallydesigned mix.

Special mixes in which aggregate packingis well controlled using complimentary gradedaggregate from crushed granite to micro silicacan be of great use in site connections. Densit

PREFABRICATION IN CONCRETE OPPORTUNITIES FOR

CONCRETE TECHNOLOGY

Dr. Howard P.J. Taylor PhD, BSc, FREng, FICE, FIStructE

Tarmac Precast Concrete Limited

54

is such a material which has been shown to becapable of making extremely effective yet smallsite connections, fully anchoring reinforcementover a few centimetres. Development of highstrength concrete in this application may bevery worthwhile.

LIGHTWEIGHT CONCRETELightweight concrete is a well known

material and has been in use for many years.Both natural and manufactured lightweightaggregates can be used and the concrete isideal for internal applications where itsexcellent thermal properties are valued.Lightweight concrete can be used in factoryprestressing, the Doncaster Grandstand roofbeing an excellent example.

On the economic front, lightweightaggregate is more expensive than denseaggregate and the 20% reduction in weightcan result in a similar reduction in potentialstrength. Lightweight concrete has a lower Evalue than dense concrete. This gives a higherprestress demand than normal denseconcretes which tends to counter the lowerweight advantage.

There is new interest in prefabrication inhousing and lightweight concrete wall panels,mirroring lightweight blocks, are of interest.Panels of this material are equally easily cut,chased or drilled by the builder or homeownerand also have thermal properties equal tolightweight blocks. Apart from the speed oferection, such panelled houses overcome theproblem of the shortage of site building skillsand provide a quality of finish and build thatcannot be achieved with blocks.

In the housing, market we may see theintroduction of foam concretes as a furtherlightweight form.

Connections and other design detailsshould be thought through to be effective,appropriate and economical. Thesedevelopments are progressing in Holland andGermany and may make some inroads in theUK market.

SELF COMPACTING CONCRETEThe precast concrete industry has used

superplasticisers for some years but modern selfcompacting concrete appears to offer evenmore opportunities. Self compacting concretecan be defined as a fully flowable concrete thatrequires no vibration or other compacting effort

to enable it to completely fill a form.

The material is immensely impressive. To filla complex mould with congestedreinforcement, fittings and penetrations bysimply pouring in the concrete with no vibrationbrings immense benefit. No vibration means nomould joint movement and no grout loss; thusarrises even around end plates are ideal and fullof cement matrix with no water loss. Fittingssdo not move under vibration neither doesreinforcement. Surface finish is also as good as,if not better, than that of vibrated concrete.There is certainly a complete absence ofaggregate transparency, often seen in unitsmade in steel moulds which required extensivevibration because of reinforcement congestion.

Providing that all the physical properties ofthe matured concrete are acceptable,remembering that precast concrete has a hugerange of application, self compacting concretewill find a place in precasting. There is the issueof cost; self compacting concretes are some20% more expensive than the concretes thatthey would replace. The benefits are lesstangible, ranging from less labour in casting togreater quality of finish, greater mould use andless noise for the operatives. The introductionof self compacting concrete into a precastfactory requires a complete assessment of theway in which the mix is made and usedinvolving a complete rethink of the wholeprocess. With appropriate investment in themix, distribution and casting system, selfcompacting concrete has the potential totransform what we do.

FIBRE CONCRETETwo fibre families are worth consideration,

polymeric and steel. Both fibre types modify theproperties of plastic immature concrete whereassteel has great benefits in fully mature concrete.

Polymer fibre concretes have benefits inmodifying the properties of plastic concrete andhave found extensive use in in situ floors. Itsincrease of toughness in immature concrete canreduce handling damage of fresh precastconcrete, protecting arrises, etc. The material isalso said to produce some anti spalling benefitsin higher strength concretes in fire. Few precastconcrete products have large open top surfaceswhere the benefits to concrete in its plastic stateare important, the only example perhaps beingthe double tee beam. The concrete tunnellining element can usefully incorporate theadvantages with respect to handling and fire.

55

Steel fibres give toughness to concretethroughout its life. The addition of steel fibresto bridge beams and other major pretensionedelements may be of benefit in reducingtransmission length cracking or even ineliminating it. The increase in cost of specialconcretes in these limited areas is notsignificant and the idea should be progressedfurther.

RECYCLED CONCRETEPrecast concrete manufacturers have

equipment that will recycle fresh concrete,separating aggregates from paste. Manycompanies have products within their rangewhere, with agreement with the client, thissaved waste can be recycled. Hardenedconcrete waste can also be crushed andreused as aggregate.

It is currently difficult to incorporatecrushed aggregate in some specificationswithout extensive testing and sampling. Manymanufacturers have products perhaps madefor a particular client where crushed materialcan be used with agreement with respect tovolumes and price. Providing that the factory'keeps on top of the problem’ these meansmay be sufficient to eliminate the need forexpensive and damaging tipping.

BLENDED CEMENTSBlended cements are with us, they have

advantages that the blending materials act aspore blockers improving resistance tocarbonation and chloride attack. In externalexposed concrete, particularly of low tomedium strength they must be of great value.

In their first uses, the ‘blend’ was carriedout by the precaster in the mixer which gaveproblems with respect to colour variations,possibly due to mixing difficulties. Thesedifficulties together with colour changes inmature slag concrete with changes in surfacemoisture gave acceptance problems in exposedconcrete. Now that a blend can be deliveredfrom the cement supplier some of theseproblems have been controlled.

The benefits of blended cements in highstrength concrete used in prestressing may notbe as large as in the lower strength grades.The prestressed bridge beam for example hasbeen shown to be immensely durable in themost arduous of locations. The disadvantageof the lower gain of strength than that whichall Portland cement concretes impart ontransfer strength and therefore mouldturnaround does increase cost. Research toquantify benefits, if any, in this area is requiredif the client is not to pay for a potential overspecification.

CONCLUSIONThis review has outlined the wide range

of concrete types that the prefabricationindustry requires and hopefully hasdemonstrated that the industry is not resistantto new ideas.

The precast industry is in a verycompetitive yet conservative market butnevertheless is prepared to invest in newmaterials and equipment if the benefits areclear. The range of products in the industry isvery large and material developments on awide front have a natural home in particularproducts in the right end use environment.

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57

Listed below are details of previous years ICT Annual Convention Symposia titles and thepapers presented. Papers from some of the earlier years, prior to 1988, are also available.Enquiries should be addressed to the Institute.

Year: PAPER: BY:

1988 CONCRETE: THE ENGINEERING MATERIAL

Symposium Chairman Mr. M.E.R. Little

The education of engineers in concrete Professor J.M. Illston

Euro-codes and Euro-standards on concrete Mr. T.W. Kirkbride- will British practice change ?

The third Sir Frederick Lea memorial lecture. Professor P.C. HewlettPerceptions of concrete - the surface

Concrete specification Mr. D.B. Storrar- its role and enforcement

Concrete - who's material Mr. C. Mansfield- the contractors viewpoint

Concrete facades and their Mr. A. Brookesaesthetic requirements

1989 EUROPE - THE CONCRETE SCENE

Symposium Chairman Mr. B. Jefferson

Hormigón σσkupoδδeµa - is it concrete ? Mr. M. Roberts

European cement Mr. P.J. Jackson

Aggregates - a standard for 1992 Mr. D.E. Brown

PFA & GGBS - their status in Dr. J. MatthewsEuropean Standards

Standard activity in Europe on Dr. B. El-Jazairiconcrete admixtures

The Channel Tunnel - link up with Europe Mr. F. Walker

Euroconcrete - ENV206 Mr. J.D. Dewar

Concrete block paving - European influences ! Mr. G.A. Griffiths

1990 CHEMICALS FOR CONCRETE CONSTRUCTION

Chairman’s opening address Professor P.C. Hewlett

The use of admixtures in concrete Mr. J.M. Dransfield

Retarded mortar systems Mr. D.H.M. Lowe

The fourth Sir Frederick Lea memorial Professor F.P. Glasserlecture. Advances in the chemistry of Portland cement

Concrete repair materials Mr. L.J. Tabor

Some aspects of modern coatings Mr. A.C. Jolly- application and properties

The evaluation of Mr. T.P. Leesanti-carbonation treatments

ANNUAL CONVENTION SYMPOSIA:PAPERS PRESENTED 1988 - 1999

58

1991 CONCRETE FOR CONSTRUCTION - HOW IS IT CHANGING ?

Symposium Chairman Professor P.F. Stott

The readymixer's overview of 1992 Dr. J.F. Troy

Specification for concrete - the changing scene Mr. J.D. Dewar

Concreting at Sizewell B Power Station Mr. L. Kotrys

Quality control and QA - a Euroview Ing.C. Souwerbren

Quality management Mr. P. Titman

European Standardisation: Dr. T.A. Harrisonrisk or opportunity

1992 CONCRETE IN HIGHWAYS AND HIGHWAY STRUCTURES

Symposium Chairman Mr. T.A. Rochester

Cementitious bases for roads Mr. J. Kennedy

Supplying ready mixed concrete for Mr. D. Bickleyhighways & highway structures

The fifth Sir Frederick Lea memorial lecture. Professor P.G. FookesThe importance of aggregates indurable highways and structures

Some observations of in-situ concrete Mr. P.L. Owensperformance as a consequence ofmodification to specifications for U.K. bridges and road pavements

Road widening, strengthening and re-cycling Mr. B. Walker- fast track and flexible concrete options

Development of concrete safety barriers Mr. M.D. Macdonald

1993 CONCRETE AND THE ENVIRONMENT

Chairman’s opening address Professor P.C. Hewlett

Present legislation and its impact on Mr. A. Baldry, MPthe concrete industry

Concrete re-cycled Ing. P. de Vries

Reducing concrete waste Dr. J.B. Newman,

Concrete for waste encapsulation Mr. E.W. Miller

The U.K. cement industry Mr. P.J. Hoddinott,andand the environment Mr. N. Roberts

The aggregate industry and the environment Mr. A. Fell

Concrete - Enhancement to nature Mr. F. Hawes

1994 HIGH PERFORMANCE CONCRETE

Chairman's keynote address Professor A.R. Cusens

High performance, high value concrete Mr. L.R. Roberts- the global picture

Pore reduced cements Dr. D.E. Macphee

Very low penetrability concrete Dr. N.R. Buenfeld

High performance concrete in practice Dr. W. Price

Middle East concrete Mr. T. Sherriff- a decade of improvement

Ultra high strength concrete Ing. B. Aarup,

59

1995 CEMENTS AND ADMIXTURES - RECENT DEVELOPMENTS

Chairman's keynote address Professor P.C. Hewlett

Activated Portland cement clinker

- Background and production Dr. S. Kelham- Uses and applications Mr. C. Justesen

Oil well cement Mr. C. Adkins

Other new developments in cements Mr. P. Livesey

Admixtures and cement interactions Mr. L.R. Roberts

Admixture cocktail- Prospective European Standards for admixtures Mr. J. Buekett- Eurostandards for mortar admixtures Mr. T.P. Lees- Underwater concrete systems Mr. L. Hodgkinson- Air entraining and superplasticised concrete Mr. R. Farmer - The Cement Admixtures Association Mr. W. Vickers

Quality Scheme

Admixtures - future developments Mr. L.H. McCurrich

Chairman's closing comments Professor P.C. Hewlett

1996 ADVANCES IN PRODUCTION TECHNOLOGY

Keynote address by the Symposium Chairman: Mr. J.D. DewarMaterials, concrete and construction - significance of the interfaces

Cement production - the state of the art Dr. G. Moir

Aggregates for concrete - the superquarry Mr. K. Larson

Production of high performance concrete Dr. Ing. M. Sandvikfor North Sea platforms

Concrete tile making in perspective Professor J.E. Bailey

ECOPAVE - paver-compacted composite road Dr. A. Mariespavement construction

1997 CONCRETE FOR THE NEXT MILLENNIUM

Chairman’s keynote address Mr. J.D. Wootton

Ready mixed concrete for the next century Mr. R. Ryle

Re-use of materials Dr. R. F. Bakker

Permeability and Carbonation - Dr. M. G. Richardsonmaking a durable concrete

Concrete in and under the sea - Ms. U. Kjaerstructures built to last

Blended cements - control of quality Dr. G. R. H. Grievein the new South Africa

Concrete in South East Asia - high Mr. C. C. Stanleyspeed, high rise and high performance

Reconstruction after the earthquake - Mr. J. E. Robertsmeasures to ensure long life in the future

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1998 MATERIALS AND MATERIALS CONTROL

Chairman’s keynote address Dr. W. F. Price

Computer methods Mr. J. D. Dewar- concrete proportioning

Modern practices for computerised control Mr. R. Phareof ready-mix concrete plants

Computer methods Dr. L. K. A. Sear- control systems

The sixth Sir Frederick Lea Memorial lecture. Professor C. L. PageCorrosion and its control inreinforced concrete

Update on European standards for Dr. P. J. Nixonconcrete and concrete materials

Recycled concrete Dr R. Collins- specification and control

Developments in the use Mr. L. R. Robertsof special admixtures

1999 INNOVATION IN CONCRETE TECHNOLOGY

Symposium Chairman Dr. J.F. Troy

Innovation Professor P.C. Hewlett

Metakaolin, a highly reactive pozzolan Mr. R. Rylefor concrete

Fibre reinforced high performance Mr. B. Aarupconcrete for precast applications

Modifying Portland Cement performance Mr. A.D.R. Brown

Non-ferrous reinforcement Professor J.L. Clarke

Specialist concrete pavement surfacing Mr. D.P. Jones

Adjusted density concrete for a Mr. D.A. Cullengravity based structure- developments and control

Architectural concrete Mr. J.G.H. Outramfeast and famine (abstract)

Copies of recent Convention papers are included in the Yearbook for the appropriate year.

Copies of the Yearbook for previous years can be obtained (subject to availability) from the ICT at a

price of £50.00. This includes postage and packing in the UK or Europe or surface mail overseas.

For airmail delivery to other countries overseas please add £5.00.

61

ADVANCED CONCRETE TECHNOLOGY DIPLOMA:SUMMARIES OF PROJECT REPORTS 1999

The project reports are an integral and important part of the ACT Diploma.

The purpose of the projects is to show that the candidates can think about a topic or problemin a logical and disciplined way, organise a programme of work and present the same in a wellstructured report. The project normally spans some six months. Significant advances can bemade and several of the projects have evolved into research programmes in their own right.

Summaries of a selection of project reports submitted during the 1998 - 1999 course are givenin the following pages.

A full list of ACT projects, dating back to 1971 when the individual project was introduced as a requirement for the

Advanced Concrete Technology Diploma examination, can be supplied on request.

Copies of the reports (except those that are confidential) are held in the British Cement Association Library and these

can be made available on loan. Subscribers to the BCA's information service, Concquest, may obtain copies on loan,

free of charge. Requests should be addressed to: The Centre for Concrete Information, British Cement Association,

Century House, Telford Avenue, Crowthorne, Berkshire RG45 6YS.

ICT members may address their requests to: The Executive Officer, Institute of Concrete Technology, P.O.Box 7827,

Crowthorne, Berkshire RG45 6FR. Copies can then be obtained from the BCA free of charge.

PROJECT TITLE: AUTHOR:

MODELLING CEMENT PERFORMANCE IN EN 196 PART 1 MORTAR: R.G. BOULTA COMPARISON BETWEEN REGRESSION AND ARTIFICIAL NEURAL NETWORK TECHNIQUES

FACTORS AFFECTING STRENGTH OF FIELD CONCRETE S. DIBANI

GREAT MAN-MADE RIVER PROJECT: S.A.A. GARGABINVESTIGATION OF CONCRETE RETARDER OVERDOSE OF ASH SHWAYREF REGULATING TANK WALLS

RECYCLING WITH HYDRATION CONTROL ADMIXTURE LIM SENG HUAT

EFFECTS OF VARYING ALKALI CONTENT OF PC42.5 CEMENT B.R. JONESAND COARSE AGGREGATE TYPE ON POZZOLANICREACTIVITY OF A TYPICAL PFA

HOW TO REDUCE THE EARLY AGE THERMAL CRACKING A.J.M. DE JONGBY USING ACCELERATORS AND RETARDERS

WATER MANAGEMENT AND USE OF RECYCLED WATER CHOW KIN KEUNGIN CONCRETE BATCHING PLACES

USE OF PELLETISED LIMESTONE-FILLER IN CONCRETE H. KOUWENHOVEN

AN EVALUATION OF THE INCLUSION OF RECYCLED AGGREGATE A.S. LEGGON THE PROPERTIES OF CONCRETE

THE USE OF CORES TO ASSESS THE IN SITU STRENGTH M.J. NORFOLKDEVELOPMENT OF CONCRETE CONTAINING PORTLANDBLASTFURNACE CEMENT

OPTIMISING CONCRETE DESIGNS USING FILLERS K.M. SHARPE

62

SUMMARYMultiple linear regression is a useful

statistical technique that can be used to makean early prediction of cement strengthperformance for quality control purposes.Early determination of strength allows plantcontrol changes to be made in time to correctany drift from the target strength. This canreduce the variability of strength and allow thetarget to be raised closer to the upper strengthlimit.

In other fields neural networks have beenused to identify patterns in large amounts ofdata. Neural networks are machines orcomputer simulations that learn by experienceand can then be used to make predictionsbased on their knowledge. Often the resultsof the neural network predictions have beenextremely good.

In this project neural network predictionshave been compared with multiple linearregression predictions to identify ifimprovements can be made from their use.

Neural networks appear to accuratelymodel the pattern in cement quality data buttheir accuracy in predicting new data onlybecomes better than multiple linear regressiononce a wide range of data is presented fortraining.

The network that was trained on thewidest range data set was used to predict datafrom a single source. The accuracy of thisprediction was disappointing, being of thesame order as the accuracy of the networktrained on data from the single source andworse than the multiple linear regression ofthis data.

It is suggested that more data records beincluded as well as increasing the number ofvariables, in particular those having a directbearing on 28 day strength, e.g. density,compaction, minor contaminants, and particlesize distribution.

MODELLING CEMENT PERFORMANCE IN EN 196 PART 1 MORTAR:A COMPARISON BETWEEN REGRESSION AND ARTIFICIAL NEURAL NETWORK TECHNIQUESBy: R.G. Boult

63

FACTORS AFFECTING STRENGTH OF FIELD CONCRETEBy: S. Dibani

SUMMARYThe project examines the factors

influencing the development of compressivestrength of concrete from the production linefor precast concrete pipes for the Great Man-Made River Project (GMRP) in Libya. Thefollowing factors were examined:

- initial curing temperature

- air content

- method of compaction

- specimen shape.

The specified 28 day cylinder strength ofthe concrete was 48 MPa.

The data indicates that both 7 and 28day compressive strengths are adverselyaffected by high initial concrete temperaturewith a loss of strength of around 1.7 MPa foreach 5˚C rise in concrete temperature. Air isincorporated in the concrete by thesuperplasticising admixture and was found todecrease in content at temperatures above19˚C. Compressive strength was found toincrease with air contents up to about 2% andthen decrease at high levels ofentrained/entrapped air. Increased workabilityleading to a reduced water demand at low aircontents was the reason given for thisphenomenon. The use of a vibrating tablerather than rodding as a means of vibratingtest specimens produced an increase in 28 daycompressive strength of almost 2.5%.However, rodding was retained for testing theproduction concrete. When both 150mmcube strength and the strength of 150mmdiameter x 300mm long cylinders werecompared, a cube/cylinder conversion factor of0.77 (for both 7 and 28 day strength) wasdeduced from the field test data. This wassignificantly different from the value of 0.86determined in the pre-production trials.

Recommendations were made forimproving the strength of the field concreteand standardising the testing methods.

64

SUMMARYAn accidental overdosing of tank wall

concrete with a retarding water-reducingadmixture during construction of the AshShwayref Regulating Tank (ART) on the GreatMan-Made River Project prompted aninvestigation of the effects of high admixturedoses (ASTM C494 Types A and D) on longterm concrete properties.

The section of tank wall affected by theadmixture overdose was still plastic whenexamined 24 hours after casting and it was stilleasy to remove concrete with a hand tool sixweeks later. Tests on the wall were madeusing both a rebound hammer and UltrasonicPulse Velocity (UPV) measurements. Therebound hammer was calibrated againstlaboratory cast concrete cylinders.

After 1 year, the rebound hammersuggested that the in situ strength of the wallwas 458 kg/m2 with a mean UPV value of 4.56km/s. This compared well with similar testsundertaken on sections of wall unaffected byadmixture overdose. A hydrostatic test on theART confirmed that the structure was fit forpurpose.

In parallel to these field studies, alaboratory testing programme examined theinfluence of various admixture dosages (0.5 -5.0% by weight of cement) in more detail.

As the level of admixture addition wasincreased, the workability increased to acollapse slump at 3% admixture. Cementsetting time increased with increasingadmixture addition up to 1% admixture. Athigher levels of admixture addition, the settingtime was reduced until, at 5% admixture, itwas approximately equal to that of the controlmix.

The development of compressivestrength was significantly delayed at levels ofadmixture addition above 1.5%. However byabout 6 months, much of the early strengthreduction had been recovered for all exceptthe very highest admixture dosage level.

The conclusions reached in the report arethat the accidental overdosing of concretewith a retarding admixture should not causemajor anxiety as the effect on concretestrength is limited to the short term and fullstrength development can be expected in duecourse. Precautions should be made,however, to deal with the retardation of earlystrength development. Prolonged curing andthe need to delay formwork striking may benecessary in such situations.

GREAT MAN-MADE RIVER PROJECT:INVESTIGATION OF CONCRETE RETARDER OVERDOSE OF ASH SHWAYREF REGULATING TANK WALLSBy: S.A.A. Gargab

65

SUMMARYHydration control or extended set control

admixtures (HCAs and ESCAs) are reputed tobe successfully used in recycling and wastemanagement in ready-mixed concreteindustries outside Singapore. This project wasundertaken to evaluate the HCA’sperformance and its commercial viability intropical weather.

Increased awareness to environmentalprotection has also led to escalating wastedisposal costs, echoing one of the biggestproblems faced by Singapore-based readymixed companies. This is notwithstanding theapproximately 23 million litres of hazardousand highly alkaline wash water generated inthe process.

In this project, HCA was evaluated as toits effects on setting time, workability andautogenous temperature rise in freshconcrete. The approach adopted in thisproject reflects the practical aspects of theHCAs application in ready-mixed concreteoperations.

Only two such systems were known atthe present time, namely the Delvo system ofMaster Builders Technology and the Recoverysystem of WR Grace. Both systems aredesigned for the same purposes and theirmethodology of application is basically similar.In this study only the Delvo system wasavailable and used throughout this project.

The study has shown that the HCAsystem worked satisfactorily resulting in ready-mixed concretes with strengths comparable, ifnot better, than the control.

A number of related operationalproblems, such as dealing with truckbreakdowns by dosing with HCA, were alsoconsidered along with a zero wastemanagement system.

Cost savings alone on the recycling ofwash water are substantial.

It is hoped that the results obtained inthis project could serve as a basis foracceptance by the local building authority andstructural engineers, who are still sceptical andapprehensive of using concrete made withrecycled materials.

RECYCLING WITH HYDRATION CONTROL ADMIXTUREBy: Lim Seng Huat

66

SUMMARYThis project attempts to measure the

relative pozzolanic performance bycomparison of a typical source of PFA withPortland cements at varying levels of alkalicontent, and also by varying the coarseaggregate type.

Comparison data was obtained by themanufacture of a large number of concretemixes in the laboratory. Research and previousstudies indicated that this was an area thathad not been extensively researched;however, there was a trend and generalopinions exist in the cement and concreteindustry that mixes containing a relatively highalkali content combined with the use oflimestone aggregates would perform the best.

The scope of the research programmeattempted to accurately measure the relativepozzolanic performance between thesevariables.

The following conclusions were drawnfrom the programme:

(1) Typically the water demand of mixescontaining 30% pfa compared to therespective PC mixes was significantlyless than the figure quoted in the BREpublication ‘Design of concretemixes’, by F G Buttler. Mixescontaining pfa gave an overall waterreduction of 1-2% per 10% of cementreplaced by pfa compared to thequoted figure of 3%.

(2) Low cement content mixes performedthe best with regard to overall waterreduction, with the level of waterreduction decreasing with increasinglevels of cement content.

(3) In terms of overall pozzolanicreactivity, the high alkali cementperformed the best; however, the lowalkali cement had a better reactivitythan the medium alkali cement,possible due to the increasedpozzolanic effect of the relatively highlevel of C3S in the cement.

(4) Overall pozzolanic reactivitythroughout the cement contentrange varied considerably with adecrease in reactivity occurring ascement contents increased. Thiscould be partially due to the greaterreduction in water content observedat the lower range of cementcontents tested. The increasedfineness of the low alkali cement mayalso be a contributionary factor.

(5) Limestone coarse aggregate, asexpected, gave the best overallpozzolanic performance and generallyoutperformed gravel and hardstoneby at least 5% when comparingstrength parity factor data.

Recommendations for the work aregiven, in particular the potential of using astrength parity factor as an indicator ofpozzolanicity rather than the k factorapproach.

EFFECTS OF VARYING ALKALI CONTENT OF PC42.5 CEMENT AND COARSE

AGGREGATE TYPE ON POZZOLANIC REACTIVITY OF A TYPICAL PFABy: B.R. Jones

67

SUMMARYThis project examines the effects of

changing the hydration process of cement onthe risk of early age thermal cracking.

For the experimental study, a B25concrete was used containing a CEM III/B 42.5blastfurnace slag cement and quartz river sandand gravel aggregates. The influence ofvarious admixtures (four accelerators ofdifferent active ingredients and two retarders)on the hydration of the concrete was thendetermined.

Semi-adiabatic heat development wasmonitored alongside measurements ofworkability to select four admixtures for furtherstudy;

- a thiocyanate/nitrate accelerator (high dose)

- triethanolamine accelerator(high dose)

- phosphate based retarder(high dose)

- phosphate based retarder(low dose).

Concretes containing these admixtures(which illustrated various different forms ofmodified hydration characteristics) were testedfor:

- workability

- adiabatic heat development

- splitting tensile strength

- dynamic modulus of elasticity.

The results of these experiments werethen used as input data for a stress analysiscomputer model which predicted the risk ofcracking in a 400mm thick concrete wallplaced on a mature and massive floor.

No correlation was found between therisk of cracking and changes in the dormantperiod before significant hydration begins (thisvaried from 3 hours to 24 hours).

Acceleration in the rate of hydration doesnot appear to increase the risk of cracking andit was inferred that a reduction in the rate ofhydration similarly would not reduce the risk ofcracking. Overall, changing the hydrationcharacteristics of concrete by the use ofaccelerating or retarding admixtures was notfelt to be a practical means of reducing the riskof early age thermal cracking in concretestructures.

HOW TO REDUCE THE EARLY AGE THERMAL CRACKING BY USING ACCELERATORS AND RETARDERSBy: A.J.M. de Jong

68

SUMMARYThis project was concerned with the

problem of returned and leftover concretesand their disposal and investigated the effectsof density and age of wash water on aircontent, setting time, slump retention andcompressive strength of concrete made fromchemically treated returns. Criteria ofperformance consistent parameters ofconcrete were set up based on comparitylimits. A control factor based on the washwater density was determined for a concretebatching plant to produce performanceconsistent concretes by using wash water. Itwas found that:

- both age and density of wash waterhad no significant effect on concretecompressive strength

- setting times were accelerated withthe increasing density of wash water

- wash water had no significant effecton concrete air content

- with increased density of wash water,water demand for mixing of freshconcrete was also increased in orderto achieve the same workability

- slump retention of fresh concrete wasaffected by density of wash water. Itwas found that concrete mixes usinghigher density of wash water wouldhave a faster slump loss.

Criteria appear to be very batching-plantdependent and conclusions drawn from thiswork may not be applicable to other ready-mixproducers.

WATER MANAGEMENT AND USE OF RECYCLED WATER INCONCRETE BATCHING PLACESBy: Chow Kin Keung

69

SUMMARYThe objective of this project was to

develop and produce a specific type of SMA-ls(pelletised fines), to examine the influence ithas on the fresh and hardened properties ofconcrete and to select a possible application.

Literature indicates that no systematicresearch has been done to identify theinfluence of fines on fresh and hardenedproperties of concrete. Information about fineswhich have been used for a longer time, likepulverised fuel ash, ground granulated blast-furnace slag and silica-fume seem to indicatethat fineness and shape influence freshproperties, and chemical compositioninfluences hardened properties.

Three readily available, clean and relativelycheap materials have been ground in a ball-mill: river-sand, limestone and pumice.Together with pulverised fuel ash and blast-furnace slag the produced powders (pumice,quartz, limestone 6, 12, 18, 23, 30, 50, 70 and90 microns) have been tested in mortars.Results show that water demand is related tobulk density. Powders with a high bulk densitygive a lower water demand. Compressivestrength is related to chemical composition,but 24-hour strength is more related tofineness. A combination of pumice (reactive)and very fine limestone gave very good results:25% of cement was replaced and compressivestrength, although only 80% after 24-hours, 7and 28 days, is equal at 91 days.

The pelletising of the fines, which is donewith water and a polymer, is the most selectivestep. Pumice could not be pelletised with thetype of polymer used. Pelletising quartz andmost of the (finest) limestone powders wouldbe too expensive (lot of polymer needed). So itwas decided to pelletise limestone 50 intoSMA-ls 50.

Replacement of cement by SMA-ls in areference-mix showed the following results.

- workability/slump: replacement ofcement by SMA-ls 50 will give a slightlybetter slump. The influence dependson the water/powder ratio

- compactibility/air content: replacementof cement by SMA-ls 50 will reduce theamount of air present in wet concrete

- bleeding: the influence of SMA-ls 50 onbleeding is not clear; further tests areneeded

- compressive strength: replacement ofcement by SMA-ls 50 will lowerstrength but at the same water/cementratio strength is higher as could beexpected from the “normal”water/cement ratio strength curve.Theoretically it could be expected thatthe relationship becomes linear,depending on the amount of cement.Not enough data are available to verifythis conclusion. Further research isnecessary

- modulus of elasticity: when a smallamount of cement is replaced by SMA-ls 50 the modulus of elasticity becomeshigher. Lowering the water/powderratio does not seem to have anyinfluence

- flexural/tensile splitting strength: the splitting strength shows lessscattering than flexural strength. Theeffect SMA-ls 50 has is the same as theeffect on compressive strength

- wear-resistance: SMA-ls 50 has anegative influence on wear-resistance

- shrinkage: at a relative humidity of 90%shrinkage does not seem to be verymuch influenced by the use of SMA-ls50. The water/cement ratio isdominant. At a lower water/powderratio absorption becomes important

- permeability/water-absorption: the useof a small amount of SMA-ls 50 insteadof cement lowers both permeability andabsorption

- microscopy: degree of hydrationdepends on water/cement ratio.

As to a possible application, thereplacement of small amounts of cement inany application where wear-resistance is not ofprimary importance. The water/cement ratioshould be slightly adjusted to get the samecompressive and tensile strength. Howeverthe modulus of elasticity will be higher.

USE OF PELLETISED LIMESTONE-FILLER IN CONCRETEBy: H. Kouwenhoven

70

SUMMARYThe increasing awareness of the

environmental impact caused by theextraction and disposal of constructionmaterials has prompted many Europeangovernments to implement policies to limit theinefficiency of such activities. Taxationschemes to encourage the recycling ofconstruction waste, based on a levy ofmaterials being disposed of to land fill, arereasonably widespread.

The government of the United Kingdom,however, is currently proposing the impositionof an aggregate tax in consideration of theGreen Lobby. A direct result of such taxationwould be a reduction in the price differentialbetween recycled and natural aggregates. Amove, to further encourage the use of recycledaggregate, which is unprecedented in Europe.

In order to assess the feasibility for awider application of recycled aggregates in thebuilt environment, this project was undertakento evaluate the possible utilisation of suchmaterial in the manufacture of ready-mixedconcrete.

The results of a literature reviewconcluded that recycled masonry and fineaggregate fractions could only be used atnominal replacement levels in relatively low-grade applications. The results of a laboratoryassessment, on the use of recycled concreteaggregate, concluded that replacement levelsof 20% could be incorporated without anysignificant reduction in quality at sustainablelevels. The use of replacement levels in excessof 20%, however, were prohibitive due toadditional cement content requirements. Itwas envisaged that difficulties experienced inpractice with quality, supply, handling, liabilityand limited customer acceptance couldseverely restrict the utilisation of recycledaggregates even in low-grade use.

Notwithstanding these negativecomments five recommendations for furtherwork are made covering absorbtivitycharacteristics, sustainability, leachate andlong term durability.

The success of any aggregate source, inthe manufacture of ready-mixed concrete,requires a balanced framework of cost,availability, quality and compliance withstandard specifications. The utilisation ofrecycled aggregates, however, currently fails toprovide such a balance. Until such time as anappropriate framework is in place, theintroduction of an aggregate tax will onlyserve to provide a significantly higher materialcost-base for the ready-mixed concreteproducer.

AN EVALUATION OF THE INCLUSION OF RECYCLED AGGREGATEON THE PROPERTIES OF CONCRETEBy: A.S. Legg

71

SUMMARYThis project examines the validity of

applying the procedures for calculatingpotential strength given in Concrete SocietyTechnical Report 11 (CSTR 11) to concretecontaining a blend of 50% Portlandcement/50% ground granulated blastfurnaceslag (ggbs).

Three concrete elements were cast usinga concrete obtained from a QSRMC approvedsupplier;

- a 1m x 1m x 1m block

- a 1.5 m x 1.5 m x 0.5 m thick wall

- a 8 m x 3 m x 0.15 m thick slab.

The concrete had a total cement contentof 325 kg/m3 and a 75 mm target slump.

A range of curing conditions, similar tothose described in CSTR 11, were applied todifferent elements and part elements. Inaddition to making a number of standardcured and temperature matched cubes fromthe concrete, the temperature developmentwithin the block and wall were also measured.

Rebound hammer readings were takenat 28 and 90 days and cores were removedfrom the various elements at 32 and 100 days.

The average 90-day strength of both thestandard cured and temperature matchedcubes was 60 MPa, but the rate of earlystrength development was much greater forthe temperature matched cubes.

When the core strengths were convertedto the potential strengths appropriate to thecuring conditions, it was found that in all casesthey were higher than the standard curedcube strengths.

The in situ strengths measured on coreswere also affected by the location of the cores,with highest strengths being recorded at thebase of the element. The increases in in situstrengths between 28 and 100 days were alsomuch greater than would be expected fromsimilar Portland cement concretes.

The report concludes that therelationship between cores and cubes is verycomplex. It is considered that the proceduresfor estimating potential strength given in CSTR11 could be applied to concretes containing acement with 50% ggbs. However, dependingon the type of curing regime employed, itsduration, the thermal history and age of theconcrete, the results could vary widely.

The report also contains an extensivereview section covering the manufacture ofggbs and the properties of concretecontaining the material.

THE USE OF CORES TO ASSESS THE IN SITU STRENGTH DEVELOPMENT OF CONCRETE CONTAINING PORTLANDBLASTFURNACE CEMENTBy: M.J. Norfolk

72

SUMMARYThis project examines the use of

limestone filler in concrete to optimise severalaspects of plastic and hardened stateperformance. Computer based mix designsoftware (Mixsim 98) was used to developsuitable mixes for testing.

The objectives of the study were toexamine optimised mixes containing limestonefiller in terms of rheology, water demand,bleed rate and capacity, cement content andcompressive strength in comparison to controlmixes without limestone filler.

Following a series of laboratory tests tocharacterise the constituent materials, mixescontaining a Portland cement based binderwith 0, 10.5%, 21% and 31% filler (by weightof total binder) and at four levels of total bindercontent were produced.

These mixes were tested for:

- slump

- flow

- plastic density

- bleed and bleeding capacity

- 1, 7, 28 day compressive strength.

The lowest water demand over a rangeof water/cement ratios was found at a level oflimestone filler of 21% of total binder. Theincorporation of additional material in theconcrete reduced bleeding at water/cementratios above 0.50. Little effect of incorporatinglimestone filler was noted in themeasurements of the rheologicalcharacteristics of the concretes.

In terms of strength development, acomparison on the basis of equalwater/cement ratio indicates that inclusion oflimestone filler as an aggregate rather than abinder increases the compressive strength ofthe concrete. However, if the limestone filler isincluded as part of the binder, the strength atequal water/binder ratio decreased as theamount of limestone filler increases.

OPTIMISING CONCRETE DESIGNS USING FILLERSBy: K.M. Sharpe

73

INDEX OF PROJECT REPORTS PRESENTED AS PART OF THEADVANCED CONCRETE TECHNOLOGY COURSE FROM 1971

SECTIONS:

(1): AGGREGATES AND THEIR EFFECTS IN MORTAR AND CONCRETE

(2): ADMIXTURES AND THEIR EFFECTS IN MORTAR AND CONCRETE

(3): CEMENTS AND THEIR EFFECTS IN MORTAR AND CONCRETE

(4): CEMENTITIOUS ADDITIONS AND THEIR EFFECTS IN

MORTAR AND CONCRETE

(5): LIGHTWEIGHT AND HEAVYWEIGHT AGGREGATES AND CONCRETE

(6): TESTING

(7): READY-MIXED CONCRETE

(8): PRECAST CONCRETE

(9): CONSTRUCTION

(10): DURABILITY

(11): MISCELLANEOUS

74

Year: Title: Author:

1971 Production and the use of aggregates in Great Britain. Brown, DE1972 The effects of crushed granite fine aggregate on.concrete strength Doyle, BJ

and workability.1972 Some observations on the use of beach sand and micaceous sand Forder, IE

in concrete.1972 Concreting aggregates in the North-East of England. Spencer, PT1972 Some aspects of the suitability of dune sand for use in concrete. Hooper, DG1972 The effects of the grading of a limestone grit used to supplement a Emery, RB

Zone 4 sand for use in ready-mixed concrete.1973 The effect of silt or clay in the fine aggregate on the Hoult, JE

workability and strength of concrete.1973 Concreting aggregates in the Cromarty Firth area. Andrews, WP1973 Some effects of a polymer flocculant on the early strength of concrete. Collinson, M1973 Lignite in concrete and the problems associated with it. Basnett, SJ1973 A review of the cements available for the detection of organic Jones, GN

impurities in fine aggregate.1974 Moisture measurement in sands. Anthony, P1974 An investigation into the efficiency and quality of production from Bowles, D

two sand and gravel plants.1974 Limestone dust and its effect on the compressive strength concrete. Dunkley, RJ1974 The development of a dry sand viscometer and some practical Frearson, J

applications of the apparatus in the aggregate and concrete industry.1974 Some properties of flint particles and their behaviour in concrete. Roeder, AR1974 An assessment of the structural and durability potentials Henrion, AAG

of aggregates for architectural concrete.1974 A survey of concreting aggregates used in West Yorkshire. Wild,W1976 An investigation into the degradation of a North of England sand Renwick, R

during mixing.1977 Laboratory and field investigations into the effects of silt contents Egglestone, HW

on the physical properties of lean concrete. 1977 The effect the flakiness of a coarse aggregate has on the properties Hills, R

of concrete.1977 Heavy media separation of lightweight particles in concrete aggregates. Jensen, AD1977 The effect of aggregate grading on the performance of flowing Rhodes, PR

concrete.1977 Chlorides in marine aggregates and their effect on the strength Robinson, M

and durability of concrete.1977 Rhodesian River sands - A study of their properties and the Smith, DV

implications of their use in concrete.1978 An investigation into the above average number of instances of Barnes, PA

frost damage during the winter of 1976 - 1977 with concrete containing Peterborough oolitic limestone gravels.

1978 An investigation into the mixing of lean-mix concrete in relation to Lee, RKthe initial moisture contents of the aggregates used.

1978 The effects of coarse aggregate grading on the properties of fresh Miller, EWand hardened concrete.

1978 An investigation into the use of coal, colliery waste and power Willis,SJstation ash in concrete for mock headings.

1979 The suitability of Nigerian natural aggregates as a concrete-making Ekwunife, RGmaterial.

1979 The effect of fine aggregate particle shape on the workability, water Hendry, DWdemand and compressive strength of concrete.

1979 The use of non-standard fine aggregates for concrete in North-West. Morris, DM1979 The relationship between Rudeloff crushing value of coarse Parka, N

aggregate and concrete strength.

ADVANCED CONCRETE TECHNOLOGY COURSE PROJECT REPORTSSECTION 1 Aggregates and their effects in mortar and concrete

75

1979 The effect of over-sanding on the water demand and strength of Potter, RJconcrete.

1981 The effect of fine aggregate grading on the properties of fresh Cepic, Nconcrete.

1981 Air-entrained concrete. Some effects of variations in the grading Sutherland, Wof blended sands.

1981 A preliminary investigation into the effect of chalk found in Norton, MSCambridgeshire flint gravels on structural concretes.

1982 A comparison of the concrete making properties of Witwatersrand Ferreira, Sand quartzite and andesite lava crushed stone fines.

1982 An investigation into some properties of white flint and their Garner, PJinfluence on the compressive strength of concrete.

1982 An investigation into the use of “as-dug” laterite conglomerate Komolafe, Cas aggregate in concrete.

1982 An investigation into the influence of crushed flint fine aggregate Richards, Ron the properties of fresh concrete.

1982 The effects of lignite on some aspects of concrete quality and Shirvill, Adurability.

1982 A report on angularity. Taylor, JV1983 An investigation into the technical and economic feasibility of Cooney, D

re-cycling of concrete demolition waste into aggregate for new concrete in Hong Kong.

1983 The effect of crushed marble dust on the compressive strength and Gibbs, JCworkability of concrete.

1983 A study of montmorillonite clay and its effect on compressive Wainwright, Sstrength and drying shrinkage of concrete.

1984 Chlorides in aggregates - an investigation into within batch variability. Course, JL1984 An investigation into the performance of concretes produced Reeks, BL

with crushed limestone aggregates, Pozzolan and different grades of Portland cement.

1986 Magnesian limestone coarse aggregate. Does it adversely Barker, PFeffect the durability of concrete.

1986 Analysis of mortar failures involving fine sands in the South-West of Calverley, KEngland.

1986 The study of decomposed granite and its effect on some of the Lo, Fproperties of concrete.

1987 An investigation into a possible method of determining the Lei, SSquality of material passing 75 micron in aggregates.

1988 The use of crushed rock fines in concrete. Ellis, G1988 An investigation of the effects of sand grading and particle shape Jones, DI

on the density, stability and strength of foamed mortar.1988 “Coral” aggregate concrete. MacCraith, S1993 The effect of coarse aggregate of different minerology on selected Clarke, PM

properties of concrete.1993 The use of “manufactured” sand in the production of precast floor Smith, B

elements.1993 An assessment of durability problems of laumonite - containing Lephoma, M

basalt aggregate for concrete.1995 ASR after two days : a case study of a phenomenon identified on Donceel, B

polished concrete floor tiles.1995 Whisper concrete - a state of the art review of whisper concrete, Parsons, G

with particular emphasis on the Foston - Hilton - Hatton by pass and surface texture and noise reduction. (CONFIDENTIAL)

1997 The effect of silt content in crushed granite fine aggregate on the Kwok, ACWstrength and workability of super plasticised concrete.

1997 The properties of crushed and uncrushed natural coarse aggregates Mosmari, Mand their effect on concrete compressive strength.

1997 An investigation into some properties of Welsh Burder gravel when Patel, Bused in concrete mixes (CONFIDENTIAL).

1999 Effects of varying alkali content of PC42.5 cement and coarse Jones, BRaggregate type on pozzolanic reactivity of a typical PFA.

1999 An evaluation of the inclusion of recycled aggregate on the Legg, ASproperties of concrete

Year: Title: Author:

76

Year: Title: Author:

1971 The effectiveness of a water-reducing admixture during prolonged Markert, NTmixing.

1971 To find the variations incurred when adding air-entraining agent to Robinson, PSready-mixed concrete.

1972 An investigation into the effect of prolonged mixing on the air Russell, GFcontent and workability of air-entrained concrete.

1972 The effect of sodium chloride on the rate of stiffening and Weaver, DCcompressive strength of concrete.

1973 An investigation into the feasibility of using an accelerated curing Hodkinson, Ktechnique to predict the strength of concrete containing water reducing agents.

1974 An investigation into the influence of the fineness of current Hall, WKproduction cements and cement contents on air entrained concrete.

1974 Superplasticised concrete and the effects of re-dosing to restore Lavery, REworkability after a delay of two hours.

1977 The influence of water-reducing admixtures on the workability and Jackson, Gstiffening time of various cements at two temperatures.

1977 The production of high strength concrete by the addition of Kjaer, Usuperplasticising admixtures.

1977 Accelerated testing of high strength concrete and concrete Sweeting, Ocontaining plasticisers using the Grant method.

1977 The effect of aggregate grading on the performance of flowing Rhodes, PRconcrete.

1978 An investigation into the effect of minimum film formation Hall, RETtemperature of latex emulsions on certain physical properties of polymer modified concrete related to industrial flooring.

1978 Air entrained in superplasticised concrete. Williams, D1979 Corrosion characteristics of air-entrained reinforced concrete. Bolan, C1979 The influence of C3A on the passivation of steel in concrete Hartley, AM

containing calcium chloride and calcium formate.1979 The use of two fluidifying admixtures to produce highworkability Molenkamp, E

concrete from standard mixes at a depot in Milton Keynes.1979 A review and investigation into some of the alternatives to the Molloy, JE

use of calcium chloride in concrete at low temperatures.1979 Scope for the use of high early strength admixtures in the precast Holland, JR

concrete industry.1980 An investigation into the storage properties of a stryrene Bowers, M

butadiene latex modified ready-mixed lime sand mortar.1980 Some aspects of workability loss in air-entrained concrete. Laffan, SM1981 Air-entrained concrete. Some effects in grading of blended sands. Sutherland, W1982 Curing membrane efficiency. Andrews, AJ1982 Workability retention in superplasticised concrete. Willis, DC1983 The development of a polymer modified concrete for use in Harris, N

under-water concreting.1984 Air-entrained concrete. A laboratory study of air loss in fresh Brown, RM

concrete when subjected to handling and vibration.1984 The effects of calcium lignosulphate admixture on concrete Lloyd, CG

properties.1985 An investigation of strength development between ready-to-use Rigg, JF

retarded mortars and bricks.1985 An investigation into the use of expanding grout admixtures in Walton, SM

sand cement grout mixes for in-situ piling applications.1986 The effect of slag substitution on the resistance of air-entrained Morton, PC

concrete to freeze-thaw cycling.1986 Admixtures for ready-mixed concrete in Thailand. Vaikakul, V1987 Concrete mortars with varied contents of microsilica,fly-ash and Andersen, T

superplasticisers.

ADVANCED CONCRETE TECHNOLOGY COURSE PROJECT REPORTSSECTION 2 Admixtures and their effects in mortar and concrete

77

1987 The effect of a polymer underwater concrete admixture on the Davies, BAbond of fresh concrete to hardened concrete.

1987 The effect of ambient temperature and agitation on the properties Lau, MTof superplasticised pfa concrete.

1987 Early strength development and maturity of OPC/PFA mixes Majek, RJcontaining plasticising admixtures.

1987 Some aspects of air entrained concrete with reference to the Seller, J1986 and earlier amendments to the DTp specification.

1987 A Middle East environment exposure study with particular Sweeney, PJemphasis on the durability performance of air entrained concrete.

1989 A comparative investigation into the properties of flowing Beattie, Aconcrete using various material combinations.

1989 Delving into Delvo. Foord, CR1989 An investigation into the discrepancies in the measurement of Howarth, DH

chlorides in concrete.1992 A comparison of freeze-thaw behaviour of C40 air-entrained Mallory, PL

and C50 non-air-entrained concrete.1993 The effect of admixtures on the workability and setting Albers, RHJ

of Diabind (CONFIDENTIAL).1993 Stability of entrained air in concretes containing air-entraining Griffin, PJ

agents and superplasticisers.1993 Cornish low water/cement ratio concrete : its drawbacks and some Stevenson, A

possible solutions exploring new mix design and admixturetechnology.

1993 An investigation into the physical and mechanical properties of Sutherland, KChigh air entrained concrete.

1993 A study of protective coatings for concrete in Hong Kong. Wan, RWM1993 Concrete aggregate strength : the effect of shape as measured by Foskin, P

the Flakiness Index on concrete aggregate strength and its effects on concrete made with aggregates of different shapes.

1993 The use of superplasticising admixtures for producing high early Naidoo, VSstrength concrete.

1994 To investigate the technical and commercial viability of air-entrained Davis, TFself compacting sand : cement mixes as a medium for reinstatement of pavements in Ireland.

1994 A study of retardation experienced in concrete manufactured using Ackroyd, AMlignosulphonate based admixtures.

1995 Evaluation of the test methods for the admixture Eurostandard. Bromwich, A1995 The effect of density on the capillary uptake characteristics of Dowson, TJ

concrete masonry with and without water repellent admixtures.1995 An evaluation of superplacticisers and silica fume in cement Forrester, RG

paste and concrete.1995 The effect of accelerators on the abrasion resistance of concrete Schutte, RC

paving blocks.1997 The effect of silt content in crushed granite fine aggregate on the Kwok, ACW

strength and workability of superplasticised concrete.1997 The use of a chemical system for the delaying of hydration in Wolfe, S

premixed concrete.1998 Introduction of admixtures into a cemented grout pack system. Barker, M1999 Great man-made river project - investigation of concrete retarder Gargab, SAA

overdose of Ash Shwayref Regulating Tank walls1999 Recycling with hydration control admixture Huat, LS1999 How to reduce the early age thermal cracking by using De Jong, AJM

accelerators and retarders

Year: Title: Author:

78

ADVANCED CONCRETE TECHNOLOGY COURSE PROJECT REPORTSSECTION 3 Cements and their effects in mortar and concrete

Year: Title: Author:

1971 Another look at the use of Portland-Pozzolan cement for the Blanton, JDcontrol of alkali-aggregate reaction.

1971 Some investigations on the formation of the grey colour of Trub, UAconcrete.

1972 Strength development of different cements at high temperatures. Luitweiler, JA1972 The hydration of Portland cement. Warner, CD1972 The comparability of methods of testing the strength development Buist, W

of cement.1972 Effects of cement fineness on bleeding and other fresh concrete Jackson, P

characteristics.1973 Strengths of mortars using masonry and a normal Portland cement. Taylor, JC1973 An investigation into the strength gain characteristics of four Avenell, R

Portland cement concretes at ages of up to 28 days.1973 A simple means of assessing the heat of hydration of cement. Adkins, C1973 A review of the cements available for the detection of organic Jones, GN

impurities in fine aggregates.1974 An investigation into the influence of the fineness of current Hall, WK

production cements and cement contents on air-entrained concrete.1974 Some effects of cement source on standard concrete mixes. Smith, L1976 Ferrocement as a material. A literature study. Jensen, JKJ1976 Effect of cement fineness on accelerated strength testing. Lee, WM1977 Glass-fibre reinforced cement. A new approach to its True, GF

benefits as permanent formwork.1977 A study of the strength of concrete using different brands of Kartomidjojo, S

Portland cement.1979 Portland blast-furnace cement. The technical and economic use Linthwaite, R

of blended cement in ready-mixed concrete.1980 The soluble alkali effect on compressive strength - a review and Butcher, HL

investigation.1980 The production, properties and applications of blast-furnace Reeves, CM

slag with particular reference to Portland blast-furnace cement concretes mortars and grouts made with Cemsave.

1982 A technical appraisal of the performance of OPC : integrally and Elsom, MRseparately ground granulated blast-furnace slag and pulverised fuel ash as partial Portland cement replacements.

1982 The effects of gypsum substitution on the workability of cement Evans, Dpaste and a concrete mix.

1982 Sulphated cement on the basis of blast-furnace slags and chemical Gelhard, RTTgypsum.

1983 The strength of Portland cement. A study of inter-relations Bannon, CAbetween producer and user methods of evaluation.

1983 An investigation into the performance of concretes produced with Reeke, BLcrushed limestone aggregates, Pozzolan and different grades of Portland cement.

1984 Effects of hot and fresh PBFC on the water demand Kroone, JPand compressive strength of concrete.

1986 An investigation into the effect of slag composition on sulfate Boulton, RAresistance of blast-furnace slag cements.

1986 A study of the influence of curing on the permeability of OPC and Sayers, PJPBFC concretes.

1987 The influence of Portland cement and microsilica cement properties Dolan, MWJon concrete workability.

1987 An assessment of the characteristics of air void size and variation in Foster, ADmixes containing blended and interground pfa cement.

79

1987 The effect of slag glass content on the compressive strength and Higson, WShydration of blast-furnace slag cement at early ages.

1987 Early strength development and maturity of OPC/PFA mixes Majek, RJcontaining plasticising admixtures.

1987 An investigation into which causes the greatest variation to Powell, WRcompressive strength : OPC or PFA.

1989 Early curing and some effect on strength and air permeability of Givens, JROPC and OPC/PFA concrete.

1989 The influence of cement characteristics on the sensitivity of concrete Rogers, ARproperties to early age temperature effects.

1989 The effects of fillers in Dunbar cement with typical Scottish Turner, Maggregates.

1989 The application of EN196 : Methods of Testing Cement; to Ackerley, RPcalcium aluminate cements.

1989 A guide to suplhoaluminate cement systems and their use in Bigley, CHcontrolling drying shrinkage in concretes and mortars.

1989 An investigation of the controlling factors in the bleeding of Rickett, SCEPortland blast-furnace cement concrete.

1989 Striking times with South African OPC with GGBS and PFA. du Preez, HTR

1992 An initial comparison of two methods of producing Portland blast Cowling, ABfurnace cement concrete.

1993 A preliminary investigation into the potential of Portland limestone Jaffer, Rcement.

1995 Effect of cement properties on the strength performance Bloomer, SJof various cements in commercial concrete.

1995 The effect of cement composition and slag and fly ash Dawes, JSreplacement on the temperature rise in simulated large concrete pours.

1995 A comparison between Lepol grate kiln cement and four stage Asima, ESsuspension pre-heater kiln cement.

1995 An investigation into some ternary blends of Portland cement, Loots, Asilica fume, fly ash and Slagment.

1997 The influence of cement sulphate on concrete strength Ryan, Mperformance (CONFIDENTIAL)

1998 The effect of in situ temperature on concrete van Heerden, H1999 Modelling cement performance in EN 196 pt 1 mortar: A comparison Boult, RG

between regression and artificial neural network techniques1999 Effects of varying alkali content of PC42.5 cement and coarse Jones, BR

aggregate type on pozzolanic reactivity of a typical PFA.

Year: Title: Author:

80

Year: Title: Author:

1971 Another look at the use of Portland-Pozzolan cement for the Blanton, JDcontrol of alkali-aggregate reaction.

1973 Pozzolan in ready-mixed concrete. Warmington, E1976 Some commercial and technical aspects of Pozzolan in concrete. Harrison, MD1976 The effect of Pozzolan on strength and heat of hydration of Omojola, A

concrete.1976 The effect of silica flour on fresh properties and strength of Marais, SRI

concrete.1978 PFA as a constituent of Portland cement concrete. Hansen, OR1978 Pozzolan - a study of the technical and economic implications of Ratcliffe, A

the use of Pozzolan.1978 An investigation into the use of coal, colliery waste and power Willis, SJ

station ash in concrete for mock headings.1979 Portland blast-furnace cement. The technical and economic use Linthwaite, R

of blended cement in ready-mixed concrete.1979 The effect of Cemsave additions on the properties of concrete cured Wainwright, P

at elevated temperatures.1980 The abrasion resistance of concretes containing blended cements. Lancaster, S1980 The production, properties and applications of blast-furnace Reeves, CM

slag with particular reference to Portland blast-furnace cement concretes mortars and grouts made with Cemsave.

1980 Bleeding rates and strength gain of OPC : PFA grouts. Rodney, N1981 Low heat concrete PFA, silica powder and a plasticiser. Rasmussen, T1982 A technical appraisal of the performance of OPC : integrally and Elsom, MR

separately ground granulated blast-furnace slag and PFA as a partial Portland cement replacement.

1982 Sulphated cement on the basis of blast-furnace slags and chemical Gelhard, RTTgypsum.

1982 A laboratory investigation of the water permeability and crushing Richards, PWstrength of concrete made with and without PFA, as affected by early curing temperature.

1982 The influence of blast-furnace slag and fly ash on the frost resistance Virtanen, Jof concrete.

1984 Effects of hot and fresh PBFC on the water demand Kroone, JPand compressive strength of concrete.

1984 An investigation into the performance of concretes produced with Reeks, BLcrushed limestone aggregates, Pozzolan and different grades of Portland cement.

1985 Ternary cementitious blends utilising OPC, ground granulated Cahillane, Jblast-furnace slag and selected PFA - a pilot study.

1985 The performance of blast-furnace slag concrete in accordance with Foley, Bcurrent British Standards and Codes of Practice.

1985 An investigation of some physical characteristics of concrete Marrison, Jincorporating granulated blast-furnace slag and made with typical ready-mix production mixes and various aggregates.

1985 The use of ground granulated blast-furnace slag in dry lean Oldham, PCconcrete. An investigation.

1986 An investigation into the effect of slag composition on the sulfate Boulton, RAresistance of blast-furnace slag cements.

1986 The effect of slag substitution on the resistance of air-entrained Morton, PCconcrete to freeze-thaw cycles.

ADVANCED CONCRETE TECHNOLOGY COURSE PROJECT REPORTSSECTION 4 Cementitious additions and their effects in

mortar and concrete

81

1986 Compositional variations between different silica fumes and their Munn, CJeffect on early structure in cement replacement.

1987 An investigation of the freeze-thaw behaviour of concrete made Child, CAwith microsilica as a partial cement replacement.

1987 Concrete mortars made with varied contents of microsilica, fly ash Anderson, Tand superplasticisers.

1987 The influence of Portland cement and microsilica cement properties Dolan, MWJon concrete workability.

1987 An assessment of the characteristics of air void size and variations in Foster, ADmixes containing blended and interground pfa cement.

1987 Early curing and some effects on strength and air permeability of Givens, JROPC and OPC/PFA concrete.

1987 A study of the possible benefits of incorporating ggbfs and Gray, Flightweight aggregate.

1987 The compactibility of no-slump concrete for hollow core slabs Juvas, Kusing microsilica and fly ash.

1987 The effects of ambient temperature and agitation on the properties Lau, MTof superplasticised pfa concrete.

1987 Early strength development and maturity of OPC/PFA mixes Majek, RJincorporating plasticising admixtures.

1987 Potential differential movements and strain characteristics of Nokes, PSpfa and ggbs blends in PQ concrete.

1987 An investigation into which causes the greatest variation to Powell, WRcompressive strength : OPC or PFA.

1988 Formwork striking times for concrete containing Ggbs - an McGibney, AGevaluation of three methods of assessment.

1989 The effect of varying 45 micron residue fraction of PFA in air Brown, MJentrained fly-ash concrete.

1989 Temperature development in thin concrete sections containing PFA. Marsh, BK1989 A combined CUSUM system for controlling OPC and Sear, LKA

OPC/PFA concretes.1989 The carbonation and oxygen permeability of OPC/ PFA and Kelham, S

Ggbs concretes.1989 An investigation into the use of limestone filler as a within mixer Latham, PM

blended cement replacement material in concrete.1990 Strength and thermal properties of silica fume foamed concrete. Pickwell, D1990 Striking times with South African OPC and GGBS and PFA. du Preez, HTR1990 Study of the relationship of actual and potential core strengths of Sehmi, HS

concrete containing PFA to assess the validity of CSTR 11 for interpretation of results.

1991 Compliance procedures for within mixer blends in relation to Brown, ADRcomposite cement standards.

1991 Permeability of silica fume concrete. Seow, KH1991 An assessment of the validity of the use of the procedures given Wright, J

in Concrete Society Technical Report No. 11 for concretes containing Ggbs.

1991 Investigation into the effects of pfa on slump retention. Rash, MF1993 A study of the introduction of pfa into concrete block manufacturing. Crowley, D1993 One use of pfa in Irish concrete : an evaluation of concrete mix Lynch, B

design using Moneypoint pfa, with particular reference to water demand and strength development.

1993 An approach to designing and monitoring strength performance of Naidoo, VRconcrete with fly ash.

1993 A comparison of permeability characteristics of blended cement Peters, AGEmixes for marine exposure conditions in the Cape Town area.

1993 The influence of condensed silica fume as a replacement binder Scott, Imaterial on the strengths of concrete.

1994 Investigation into inconsistent and low 28 day compressive Mackenzie, MCstrengths experience with mixes containing 50% OPC and 50% MGBS at Hippo Ready Mixed Concrete.

Year: Title: Author:

82

1995 The use of microsilica concrete in the Gulf region. Bustami, AS1995 The effect of cement composition and slag and fly ash Dawes, JS

replacement on the temperature rise in simulated large concrete pours.

1995 An investigation into the relative performance of different Price, ARcement/pfa combinations in commercial concrete (CONFIDENTIAL).

1995 An evaluation of superplasticisers and silica fume in cement paste Forrester, RGand concrete.

1995 An investigation into some properties of fresh and hardened Loots, Aconcrete containing ternary blends of ordinary Portland cement, silica fume, fly ash and slagment.

1996 The use of OPC/PFA blended cement as a substitute for SRC in Tiernan, Mshotcrete at Tara Mines Ltd.

1997 An assessment of maturity functions for high slag blastfurnace Lesuff, SEcement concretes.

1997 High slag blastfurnace cement for high strength concrete. de Veer, T1997 An investigation into the variability of United Kingdom Portland Gaimster, R

cement-pulverised fuel ash concretes, in terms of compressivestrength performance.

1998 The suitability of a MC22,5X cement in low strength concrete Bonser, RGunder typical South African site conditions

1998 The production of clinker containing paint waste: burnability, Smith, JHclinker behaviour and concrete behaviour

1999 Effects of varying alkali content of PC42.5 cement and coarse Jones, BRaggregate type on pozzolanic reactivity of a typical PFA.

1999 Use of pelletised limestone-filler in concrete Kouwenhoven, H1999 The use of cores to assess the in situ strength development of Norfolk, MJ

concrete containing Portland blastfurnace cement1999 Optimising concrete designs using fillers Sharpe, KM

Year: Title: Author:

83

ADVANCED CONCRETE TECHNOLOGY COURSE PROJECT REPORTSSECTION 5 Lightweight and heavyweight aggregates and concrete

Year: Title: Author:

1972 Effects of aggregate shape on strength of structural lightweight Czuryskiewicz, Aaggregate concrete.

1974 An investigation into the possibility of producing an artificial aggregate from pulverized fuel ash and furnace bottom ash by cement stabilization. Wetherill, DM

1976 The lightweight aggregate Korlin. Bakker, H1980 Structural lightweight aggregate concrete - the development of a Nadhirsh

mix design method. Masruri1980 The effect of prolonged mixing times on the workability of Leca Simpson, CA

lightweight concrete.1981 The development of a pumpable mix using Barytes aggregate Macrae, DJ

giving a density of 3500 kg/m3 and a strength of 21 N/mm2 at 28 days.

1983 Magnetite concrete: The development, production and control of Binns, RAa high density mix.

1987 A study of the possible benefits of incorporating ggbfs Gray, Fwith lightweight aggregate.

1988 An investigation into some problems associated with pumping Murphy, MLytag concrete.

1992 Development of a lightweight cementitious material to be used Mostert, HFin deep level mining support systems (CONFIDENTIAL).

84

Year: Title: Author:

1971 An approximate method for estimating the total heat envolved in Adams, MAconcrete at early ages.

1971 The relationship between concrete cores and cubes. Channel, JV1971 Tensile splitting of concrete cubes. Curl, WPH1971 Investigation into the comparative performance of three testing Drake, RJ

machines in the Midlands area.1972 A comparison between destructive and non-destructive testing Smith, DWE

for concrete strength.1972 The comparability of methods testing the strength development Buist, W

of cement.1972 Mechanical damage to new concrete, a means to assess the Leodolf, GF

energy involved.1972 The determination of density and absorption variability within Cannon, RP

concrete paving slabs using a gamma ray backscatter gauge.1972 The control of ready-mixed concrete using the indirect tensile test Sherriff, T

- an appreciation of the DoE requirements.1972 The cube splitting test. A method of determining the tensile Thomas, AJ

strength of concrete.1973 An investigation into the feasibilty of using an accelerated curing Hodkinson, K

technique to predict the strength of concrete containing water reducing agents.

1973 A preliminary investigation of the Hobart mixer as a method of Horton, AJMassessing workability.

1973 An examination of the feasibility of ultrasonic testing for strength Ashman, AEcontrol of precast concrete pipes.

1973 A simple means of assessing the heat of hydration of cement. Adkins, C1973 A study of the indirect tensile compressive strength relationship. Keeley, C1973 The performance of a modified slump cone. Watson, RV1974 The effect of deviations from planeness of mould walls Dennett, B

on measured cube strength.1974 Effect of cube delivery time on subsequent strength. Baker, LR1974 The development of a dry sand viscometer and some practical Frearson, JP

applications of the apparatus in the aggregate and concrete industry.1974 An appraisal of existing methods used for measuring the Hockley, EG

workability of masonry cement mortars and an application of a two point test to assess its rheological properties.

1974 An investigation of certain aspects of curing and their effect on Proudman, PJmeasuring cube strength.

1976 An investigation into the carbonation of concrete with relation Blakeman, JSto hardened concrete analysis.

1976 Accelerated strength testing of concrete with a view Hill, AEto judging for compliance.

1976 The effect of cement fineness on accelerated strength testing. Lee, WM1976 An investigation of the influence of casting and initial curing Pitcher, DC

temperature on the strength of 28 day cubes.1976 Investigation into the mortar prism test. Russell, DR1977 The nitrogen gas test for tensile strength of concrete. Gibson, CM1977 A feasibility study of the ultrasonic pulse velocity technique as a Greig, N

method of assessing the extent of fire damage in concrete.1977 An assessment of the Schmidt Rebound Hammer as a method of Plimmer, JM

determining the potential surface wearing characteristics of industrial concrete floors.

1977 The RAM-ifications of truck mixed concrete. Stubbs, HA

ADVANCED CONCRETE TECHNOLOGY COURSE PROJECT REPORTSSECTION 6 Testing

85

1977 Accelerated testing of high strength concrete and concrete Sweeting, OIcontaining plasticisers using the Grant method.

1977 A laboratory comparison between metal and plastic cube moulds. Winstanley, B1978 The relation between breaking load and non destructive tests Grebin, G

on concrete pipes.1978 Precision of testing ready-mixed concrete for cement content. Herowych, WJ1978 The use of ultrasonic pulse velocity measurement to determine Richardson, JG

transfer times for prestressed concrete produced using pretensioning methods.

1979 A study and investigation of the application of ultrasonic pulse Callander, Ivelocity for quality control of readymixed concrete.

1979 Effects of screening concrete on its compressive strength. Harold-Barry, HR1979 In-situ testing of building mortars. A preliminary investigation. Lees, TP1979 The relationship between Rudeloff crushing value of coarse Parka, N

aggregate and concrete strength.1979 The measurement of the tensile strength of concrete : a critical Torrent, RJ

discussion.1979 An investigation into some properties of sand cement floor screed Travis, CJG

material and an assessment of cube splitting as a bond test.1980 Freeze-thaw durability tests upon concrete paving block Clark, AJ

specimens.1980 Chemical analysis of hardened concrete, an investigation of Skinner, MG

within batch variation and its effects on unit cement content.1981 Laboratory investigation into factors affecting U.P.V. values. Montesin, F1981 An evaluation of the BRE Internal Fracture Test Method. Print, MH1981 The effect of direction of loading on the apparent compressive Turner, DR

strength of lean concrete cubes.1982 The development of a small mould for the study of plastic Cooper, CR

shrinkage cracking of 20mm aggregate concrete.1983 An assessment of ultrasonic pulse velocity in production concrete Hutton, DM

in the Eastern Province of Saudi Arabia.1984 An evaluation of vacuum flask calorimetry as a method for Dean, MP

predicting later age compressive strength.1984 Air entrainment testing of concrete pavement using a nuclear Nicholson, E

density gauge and Chase air indicator.1985 A study of an abrasion test for concrete and some of the factors Connell, MD

affecting abrasion resistance.1986 An investigation into the effect of ambient conditions on Initial Keighley, JS

Surface Absorption and Surface Hardness.1986 A study of the influence of curing on the permeability of OPC Sayers, PJ

and PBFC concretes.1986 An investigation to determine whether the saturated density of cube Wilson, AT

specimens can be used to monitor the plastic density of concrete.1987 Delayed analysis of fresh concrete for cement and water content. Clear, CA1987 Development of a permeability apparatus for concrete. Day, RI1987 An investigation into a possible method of determining the Lei, SS

quality of material passing 75 microns in aggregate.1987 An assessment of correlation between cores and characteristic Phillips, RN

cube strength.1988 An investigation into methods of improving the ability of the Bellamy, AA

chemical test for ASR to distinguish between aggregates of differing reactivity.

1988 The density method of determination of alkali reactivity Madsen, PKof fine aggregate concrete.

1988 An investigation into methods of retarding fresh concrete for Taylor, HDsubsequent RAM testing within the guidelines of the RAM testing network.

1989 The application of EN196 : Methods of Testing Cement, Ackerley, RPto calcium aluminate cements.

1989 An exploratory study of tests to measure shear bond strength of Collie, FAconcrete at joints.

Year: Title: Author:

86

1989 An investigation into the discrepancies in the measurement of Howarth, DHchlorides in concrete.

1989 Study of the relationship of actual and potential core strengths of Sehmi, HSconcrete containing PFA, to assess the validity of CSTR 11 for interpretation of the results.

1989 Neutron radiation for the determination of the water content in De Vries, Pfresh concrete.

1991 A practical method for assessing the early in-situ strength of Nicklinson, Aconcrete.

1991 An assessment of the validity of the use of the procedures given Wright, Jin Concrete Society Technical Report No. 11 for concretes containing Ggbs.

1991 An investigation into SABS method 1085. "Initial drying Goodman, HJshrinkage and wetting expansion of concrete".

1991 Electrical methods for measuring for microstructure and moisture Jackman, SIstates of concreting materials.

1993 An assessment of the two point workability test as a control West, RPmethod for the retempering of fresh concrete.

1995 The relationship between heat measurement of mortars, using Angel, SJa semi adiabatic calorimeter, and the compressive strengths of mortars.

1995 An investigation into the effects of non standard curing regimes Berrie, IRon the compressive strength of concrete cube specimens.

1995 Evaluation of the test methods for the admixture Eurostandard. Bromwich, A1995 Effect of transportation on fresh concrete cube samples. Brown, RC1995 Testing for quality of mortar and masonry units for use Butlion, PH

in construction by developing communities.1996 Some aspects of shotcrete and its boiled water absorption Meadows, JF

measurement as used on the transfer tunnel of the LesothoHighlands Water Project.

1997 The monitoring of compressive strength in production cements O’Brien, DGusing commercial concrete mixes.

1997 An investigation into the use of density as a control parameter in Dudden, Jconcrete block manufacture (CONFIDENTIAL).

1997 A replacement for the trichloroethane in the determination of Lay, Jcapillary porosity to BS 1881: Part 124.

1997 An assessment and reason for the deterioration of the reinforced Mollart, Jconcrete elements in bridges to show the economic viability ofa routine testing regime.

1998 The effect of in situ temperature on concrete van Heerden, H1999 The use of cores to assess the in situ strength development of Norfolk, MJ

concrete containing Portland blastfurnace cement

Year: Title: Author:

87

Year: Title: Author:

1971 To find the variations incurred when adding air-entraining Robinson, PJagent to ready-mixed concrete.

1971 Comparing test cube results of ready-mixed concrete samples at Walker, Fdepot and on site.

1972 The control of ready-mixed concrete using the indirect tensile test - Sherriff, Tan appreciation of the DoE requirements.

1972 A study of the comparison of the variability of ready-mixed King, DGconcrete produced by central mixing and truck mixing plants.

1972 An investigation into the re-use of wash-water as mixing water Bath, DWin concrete.

1972 A comparison of truck mixed and plant mixed ready-mixed Parnell, GGconcrete.

1973 The possibilites and the advantages of the warming of ready-mixed Katajisto, Rconcrete.

1973 An investigation into automatic control of concrete workability. Smy, RA1973 Pozzolan in ready-mixed concrete - some preliminary experiments. Warmington, E1974 Effect of cube delivery time on subsequent strength. Baker, LR1974 Concrete workability - its assessment and adjustment. Garstone, R1974 The effects of the grading of a limestone grit used to supplement a Emery, RB

Zone 4 sand for use in ready-mixed concrete.1976 Truck mixing (CONFIDENTIAL). Scales, R1977 A pilot investigation of a new approach to the quality control of Kirkhope, W

the materials and plant used to produce ready-mixed concrete.1977 The RAM-ifications of truck mixed concrete. Stubbs, HA1978 An instruction manual for the training of laboratory technicians, Eriksen, DJ

sales representatives and selected personnel by Ready Mixed Concrete (Natal) Pty Ltd.

1978 Precision of testing ready-mixed concrete for cement content. Herowych, WS1978 An investigation into the mixing of lean mix concrete in relation to Lee, RK

the initial moisture contents of the aggregates used.1979 The effects of agitation and non-agitation on the properties of Haider Abidi, SM

concrete in Middle East climatic conditions.1979 A study and investigation of the application of UPV for quality control Callander, IA

of ready-mixed concrete.1979 Portland blast-furnace cement. The technical and economic use Linthwaite, R

of blended cement in ready-mixed concrete.1979 The use of two fluidifying admixtures to produce high workability Molenkamp, E

concrete from standard mixes at a depot in Milton Keynes.1980 An investigation to examine the within batch variability of truck Bruce, MG

mixed lean concrete.1981 The production of pre-cooled plastic concrete. Pepper, SD1985 An investigation of some physical characteristics of concrete Marrison, J

incorporating GGBFS and made with typical ready-mix concrete.1986 Admixtures for ready-mixed concrete in Thailand. Vaikakul, V1987 The effect of ambient temperature and agitation on the properties Lau, MT

of superplasticised pfa concrete.1993 Central type concrete mixing mechanism vs truck type concrete Abu-Zaid, M

mixing mechanism.1993 An investigation into how some properties of concrete are affected Gibb, I

when reclaimed slurry water is used in its production (CONFIDENTIAL).1993 Rheology of fresh mortar and its possible link to readymix Mulder, R

concrete in transition.1994 Investigation into inconsistent and low 28 day compressive Mackenzie, MC

strengths experienced with mixes containing 50% OPC and 50% MGBS at Hippo Ready Mixed Concrete.

ADVANCED CONCRETE TECHNOLOGY COURSE PROJECT REPORTS SECTION 7 Ready-mixed concrete

88

1995 Effect of transportation on fresh concrete cube samples. Brown, RC1995 An investigation into how some of the plastic and hardened Cullen, E

properties of high workability concretes are affected by altering mix design properties (CONFIDENTIAL).

1996 An investigation into the effect of high ambient temperature on the Prendergast, MNcompressive strength of ready mix concrete in Ireland during 1995.

1997 The use of a chemical system for the delaying of hydration in Wolfe, Spremixed concrete.

1998 Concrete mix design system and quality control - a practical approach. Peter, MBR1999 Recycling with hydration control admixture. Huat, LS1999 Water management and use of recycled water in concrete Keung, CK

batching places.

Year: Title: Author:

89

Year: Title: Author:

1971 A reading study of architectural precast concrete. Mescal, R1972 The determination of density and absorption variability within Cannon, RP

concrete paving slabs using gamma ray backscatter gauge.1972 Investigation into the effect of mix variability on the Smith, BE

physical properties of concrete roofing tiles.1973 An investigation into automatic control of concrete workability. Smy, RA1973 An examination of the feasibility of ultrasonic testing Ashman, AE

for strength control of precast concrete pipes.1974 Concrete workability - its assessment and adjustment. Garstone, R1974 As assessment of the structural and durability potentials Henrion, AAG

of aggregates for architectural concrete.1976 The performance of low pressure steam curing chambers Masson, GF

in a concrete block works and some aspects of block strength.1977 A review of precast exposed aggregate cladding panels. Prior, G1978 The use of ultra sonic pulse velocity measurement to Richardson, JG

determine transfer times for prestressed concrete using pretensioning methods.

1979 Scope for the use of high early strength admixtures in the precast Holland, JRAconcrete industry.

1980 Freeze-thaw durability tests upon concrete paving block specimens. Clark, AJ1980 The effects of "lime" on the compressive strength of Okafor, AO

Sandcrete blocks.1984 Curing concrete components in high insulated methods .Jensen, PF1984 An investigation of transmission length in pretensioned Richards, CB

concrete beams containing fully bonded and partially bonded tendons.

1984 The development of an improved early curing regime Strange, Pfor the manufacture of small precast reinforced concrete elements.

1985 Concrete shaft linings on South African Goldmines - the state Benn, BTof the art.

1986 Precast concrete production. A critical examination of Miller, Aperformance.

1987 The workability of hydraulically pressed concrete. Kay, DA1988 An investigation into some problems associated with Murphy, M

pumping Lytag concrete.1989 Underground support enhancement using cement-based Thomson, JA

materials. A critical review of current practice.1993 A study of the introduction of pfa into concrete block Crowley, D

manufacturing.1993 The use of "manufactured" sand in the production of Smith, B

precast concrete floor elements.1995 Grouting of tendons in prestressed concrete : rheology and Bouquet, GC

flow properties of injection grouts.1995 The effect of accelerators on the abrasion resistance of Schutte, RC

concrete paving blocks.1996 Strength variability within solid concrete masonry blocks Fitzgerald, F

manufactured by mobile multi-block laying machines (egg layers).1997 An investigation into the use of density as a control parameter Dudden, J

in concrete block production (CONFIDENTIAL).1997 Prestressed concrete cylinder pipe with particular reference to Dozan, A

those used in the Great Man Made River Project (Libya).1997 An investigation of production methods and material types Nessfield, CD

for precast concrete block paving.

ADVANCED CONCRETE TECHNOLOGY COURSE PROJECT REPORTS SECTION 8 Precast concrete

90

Year: Title: Author:

1973 The effect of varying stabilisation methods on the early Nash, DJthermal movement of typical South African Cape Province materials.

1974 The variation and specification of water/cement in structural Corish, ATconcrete.

1976 The effect of vacuum treatment on some properties of concrete Timmermans, Hand the use of the vacuum process in South Africa in general.

1977 Design recommendations for circular concrete hinges. Crossley, AN1979 A survey of problems encountered in construction operations Agu, DIC

in Nigeria.1979 Increasing the strength of air cured hardened concrete by Peplow, CTB

later water curing.1982 The effectiveness of repairs made from concrete with Taylor, G

polymer modifiers.1984 Investigation of membranes, water tightness, elasticity and Thorsen, TS

adherence.1985 The inspection, maintenance and repair of reinforced Carter, L

concrete buildings, including defect diagnosis.1985 An investigation into the effects of joints formed at various Davey, PN

ages on the tensile strength of concrete.1985 A survey of concrete construction in the area of Port Harcourt and Magboh, TC

environs.1985 Concreting in hot climates with particular interest to the Quandeel, YM

Middle East.1985 Flowing success. Roberts, MR1986 Early-age thermal check control in concrete swimming pools. Frandsen, J1986 Hot weather concreting. The Saudi Arabia - Bahrain McWhannell, G

Causeway.1986 Concrete mixes for reinforcement penetration into continuous Fowler, DB

flight auger piles.1986 Precast concrete production. A critical examination of Miller, A

performance.1987 The workability of hydraulically pressed concrete. Kay, DA1989 An investigation into some problems associated with Murphy, M

pumping Lytag concrete.1990 Underground support enhancement using cement-based Thomson, JA

materials. A critical review of current practice.1990 Quality cast stone (confidential). Bell, JG1990 Release agents and their effect on surface finish when used Newby, P

on steel moulds.1991 Durability of concrete pipes. Fawcett, SE1993 Bond strength of reinforced concrete at construction joints Kotrys, L

prepared by retarders.1993 Development of high strength concrete for the Malaysian Ting, HY

construction industry.1993 Current practices in achieving concrete finishes to civil Adams, R

engineering structures in Ireland from a contractor's viewpoint.1993 A study of abrasion resistance of concrete and terrazzo Halloran, KM

tiles to traffic.1993 Controlled permeability formwork : a review and pilot study Richardson, MG

of early age and medium term characteristics of inclined concrete surfaces.

ADVANCED CONCRETE TECHNOLOGY COURSE PROJECT REPORTSSECTION 9 Construction

91

Year: Title: Author:

1995 Effect of post cooling systems at Katse dam. Kotola, K1995 Testing for quality of mortar and masonry units for use in Butlion, PH

construction by developing countries.1996 Some aspects of shotcrete and its boiled water absorption Meadows, JF

measurement as used on the transfer tunnel of the Lesotho Highlands Water Project.

1996 Optimising the drying period of concrete ground floor slabs Shearman, Gprior to the application of sealant floor finishes.

1996 Aircraft pavement - an overview. Walsh, M1997 Re-use of rebound materials in sprayed mortar and their effect Saffour, MA

on mortar quality.1997 Great Man Made River Project - Garabulli regulating tank - Arateeb, A

appraisal of structural concrete.1999 Factors affecting strength of field concrete Dibani,S1999 Great man-made river project - investigation of concrete retarder Gargab, SAA

overdose of Ash Shwayref regulating tank walls1999 How to reduce the early age thermal cracking by using De Jong, AJM

accelerators and retarders

92

Year: Title: Author:

1971 Another look at the use of Portland-Pozzolan cement for the Blanton, JDcontrol of alkali-aggregate reaction.

1971 Concrete in a marine environment. Payne, JC1971 The durability of concrete in marine structures. Wootten, JD1974 An assessment of the structural and durability potentials of Henrion, AAG

aggregates for architectural concrete.1974 An investigation into the relative importance of some adverse Roberts, M

conditions in the early cracking of reinforced concrete.1977 Chlorides in marine aggregates and their effect on the strength and Robinson, MJ

durability of concrete.1978 An investigation into the above average number of instances of Barnes, PA

frost damage during the winter of 1976/77 with concrete containing the Peterborough Oolitic limestone gravels.

1978 Plastic cracking - accident or (mix) design. Lord, BA1979 Corrosion characteristics of air entrained reinforced concrete. Bolan, C1979 The influence of C3A on the passivation of steel in the concrete Hartley, AM

containing calcium chloride and calcium formate.1980 The abrasion resistance of concretes containing blended cements. Lancaster, S1981 A pilot study into the resistance of varying types of concrete to Weston, K

cycles of freezing and thawing.1982 The development of a small mould for the study of plastic shrinkage Cooper, CR

cracking of 20mm aggregate concrete.1982 The effects of lignite on some aspects of concrete quality and Shirvill, AJ

durability.1982 The effectiveness of repairs made from concrete with polymer Taylor, G

modifiers.1982 The influence of blast-furnace slag and fly-ash on the frost Virtanen, J

resistance of concrete.1983 The durability of concrete. A guide for the concrete technologist. Bamford, JR1985 Reinforced concrete deterioration. Ibn Sinna School - Bahrain. Almoayed, H1985 A study of an abrasion test for concrete and some factors Connell, MD

affecting abrasion resistance.1985 Cover and its influence on durability. Evans, DJ1986 Magnesian limestone coarse aggregate. Does its use adversely Barker, PF

affect the durability of concrete.1986 An investigation into the effect of slag composition on the Boulton, RA

sulfate resistance of blast-furnace slag cements.1986 Experimental research on the durability of concrete subjected to Buenfeld, NR

freezing and thawing in seawater.1986 The effect of slag substitution on the resistance of air entrained Morton, PC

concrete to freeze-thaw cycling.1986 The effect of re-tempering masonry mortar upon compressive Newson, MJ

strength and freeze-thaw durability.1987 An investigation of the freeze-thaw behaviour of concrete made Child, CA

with microsilica as a partial cement replacement.1987 A Middle East environment exposure study with particular Sweeney, PJ

emphasis on the durability performance of air entrained concrete.1988 An investigation into the freeze-thaw durability of high strength Jones, JD

concrete.1988 The carbonation and oxygen permeability of OPC, PFA and Ggbs Kelham, S

concretes.1992 A comparison of freeze-thaw behaviour of C40 air entrained and Mallory, PL

C50 non-air-entrained concrete.

ADVANCED CONCRETE TECHNOLOGY COURSE PROJECT REPORTSSECTION 10 Durability

93

Year: Title: Author:

1993 To study the effect of cement content and water content varations Chan, WWon durability of concrete of the same grade.

1993 A study of protective coatings for concrete in Hong Kong. Wan, RWM1993 An assessment of durability problems of laumonite - containing Lephoma, M

basalt aggregate for concrete.1995 An initial investigation into the freeze-thaw resistance properties of Amos, SM

concrete incorporating polypropylene fibres as an alternative to air entrainment (CONFIDENTIAL).

1997 An assessment and reason for the deteriation of the reinforced Mollart, Jconcrete elements in bridges to show the economic viability of a routine testing regime.

1997 Low permeability concrete (CONFIDENTIAL). Eastwood, C1997 A comparison between four different protective coating systems Ibrahim, A

for prestressed concrete cylinder pipes exposed internally to aggressive water.

1998 Assessment and relevance of soft water attack studies/methods Diaho, KIin the Lesotho Highlands Water Project.

94

Year: Title: Author:

1971 Pumping operation details. King, JET1972 Steel fibre reinforced concrete. Stanley, CC1972 The study of skid resistance improvement by the embedding of Yalcin, E

calcined bauxite in concrete surfaces.1972 A view of green concrete. Bakker, RFM1972 Statistical methods in the concrete industry especially in the Buyck, AE

Netherlands 1972.1973 Polymer concrete : A general review and discussion. Hill, LG1973 Effect of bentonite on the bond between steel reinforcement Omojola, A

and concrete.1974 An investigation into colour pigment for use in concrete. Beningfield, N1974 A survey of lean mix concrete. Crane, PW1974 The fluidity of the concrete components. Verkerk, B1974 An investigation into the possibility of producing an artificial

aggregate from pulverized fuel ash and furnace bottom ash by cement stabilization. Wetherill, DM

1976 The relation between void content and the bleeding of concrete. Martin, SJ1977 The application of computers to concrete quality control. Castle, O1977 The effects of temperature and time on workability and other Njimogu, BS

properties of concrete.1977 An investigation into the relative importance of some adverse Roberts, M

conditions in the early cracking of reinforced concrete.1978 Plastic cracking - accident or (mix) design. Lord, BA1978 Current practice in Indonesian concrete production. Sumardi, K

Implementation of some recommended improvements.1979 Heating system for concrete. Koivupalo, A1980 Polypropylene fibre-reinforced concrete. Covarrubias, JP1981 The production of pre-cooled plastic concrete. Pepper, SD1982 Curing membrane efficiency. Andrews, AJ1983 An investigation into the technical and economic feasibility of Cooney, D

recycling of concrete demolition waste into aggregate for new concrete in Hong Kong.

1983 Accreditation of concrete testing laboratories. Gomez-Toledo, C1984 A guide to concreting materials in Baghdad. McQuaid, D1984 Computers and concrete - A review of some applications in Walker, AJ

production casting and curing, testing, quality control and mix design.1984 Designer's guide to the selection of concrete grade. Wilson, RA1985 An investigation of strength development between ready-to-use Rigg, JF

retarded mortars and bricks.1985 An investigation into the use of expanding grout admixtures in Walton, SDM

sand cement grout mixes for in-situ piling applications.1986 Compositional variations between different silica fumes and their Munn, CJ

effect on early structure in cement and concrete.1990 An investigation into the effects of including polypropylene Gold, SJ

fibres on certain properties of fresh and hardened concrete.1990 State of the art report - Fusion bonded epoxy coated Messham, MR

reinforcement.1991 An investigation into the effect of using liquid nitrogen to cool Bell, MD

high temperature concrete.1991 The effects of hot cement on properties of concrete Bowerman, DS1991 The influence of polypropylene fibre aspect ratio on concrete Dowie, NC

properties.1991 Soil-cement as an alternative to Type 1 sub-base. Ingham, B1991 Pellite as a structural concrete. Mitchell, M1991 Experience with a computerised approach to concrete mix design. Wood, J

ADVANCED CONCRETE TECHNOLOGY COURSE PROJECT REPORTSSECTION 11 Miscellaneous

95

Year: Title: Author:

1991 A laboratory study on the effect of liquid nitrogen on high Wu, YTAstrength concrete.

1992 An investigation into the use of sea water in concrete. Sephton, SS1993 Ardnacrusha Power Station : concrete performance 60 years on. McGuire, M1993 An investigation of some 40 year old concrete paving. Wallace, OB1993 Compressive and flexural bond strength in mortars. Wren, D1994 A study of East Lodge reinforced concrete bridge, University College, Roche, E

Cork, Ireland.1995 An investigation into how to incorporate the addition of water Austin, R

reducing admixtures into the MIXSIM computer program.1995 Grouting of tendons in prestressed concrete : rheology and Bouquet, GC

flow properties of injection grouts.1995 An investigation into how some of the plastic and hardened Cullen, E

properties of high workability concretes are altered by altering mix design properties (CONFIDENTIAL).

1995 Research into validity - sphere of maturity method "De Vree". Dekker, I1995 Whisper concrete - a state of the art review of whisper concrete, Parsons, G

with particular emphasis on the Foston - Hilton - Hatton by pass and surface texture and noise reduction (CONFIDENTIAL).

1995 High density concrete for radiation shielding. Schulte, SR1995 Testing for quality of mortar and masonry units for use in Butlion, PH

construction by developing communities. 1997 Re-use of rebound materials in sprayed mortar and their effect Saffour, MA

on mortar quality.1997 A comparison between four different protective coating systems Ibrahim, A

for pre stressed concrete cylinder pipes exposed internally toaggressive water.

1997 An investigation in the fresh properties of high performance Awad, Kconcrete.

1998 Introduction of admixtures into a cemented grout pack system Barker, M1998 Splitting cracks in pretensioned prestressed concrete turnout sleepers. Papenfus, NJ1998 The production of clinker containing paint waste: burnability, Smith, JH

clinker behaviour and concrete behaviour.1999 Factors affecting strength of field concrete Dibani,S1999 Optimising concrete designs using fillers Sharpe, KM

96

ICT RELATED INSTITUTIONS & ORGANISATIONS

ASSOCIATION OF INDUSTRIALFLOORING CONTRACTORS33 Oxford StreetLeamington SpaCV32 4RATel: 01926 833 633www.concrete.org.uk/acifc

ASSOCIATION OFCONSULTING ENGINEERSAlliance House12 Caxton StreetLondon SW1H 0QLTel: 020 7222 6557www.acenet.co.uk

ASSOCIATION OF LIGHTWEIGHTAGGREGATE MANUFACTURERSC/O: East Coast Slag Products LtdStantonScunthorpeN.Lincs DN16 1XYTel: 01724 856444

BRE (BUILDING RESEARCHESTABLISHMENT) LTDBucknalls LaneGarstonWatford WD2 7JRTel: 01923 664000www.bre.co.uk

BRITISH BOARD OF AGRÉMENTP.O.Box 195Bucknalls LaneGarstonWatfordHerts WD2 7NGTel: 01923 665341www.bbacerts.co.uk

BRITISH CEMENT ASSOCIATIONTelford AvenueCrowthorneBerks RG45 6YSTel: 01344 762676www.bca.org.uk

BRITISH PRECASTCONCRETE FEDERATION60 Charles StreetLeicester LE1 1FBTel: 0116 253 6161www.britishprecast.org.uk

BSI STANDARDSBritish Standards House389 Chiswick High RoadLondon W4 4ALTel: 020 8996 7000www.bsi.org.uk

BRITPAVEBritish In-Situ ConcretePaving AssociationTelford AvenueCrowthorneBerks RG45 6YSTel: 01344 725731www.bca.org.uk

CEMENT ADMIXTURESASSOCIATION38a Tilehouse Green LaneKnowleWest MidlandsB93 9EYTel: 01564 776362

CONCRETE ADVISORY SERVICE37 Cowbridge RoadPontyclunNr. CardiffWales CF72 9EBTel: 01443 237210www.concrete.org.uk

CONCRETE BRIDGEDEVELOPMENT GROUPTelford AvenueCrowthorneBerks RG45 6YSTel: 01344 762676

CONCRETE REPAIR ASSOCIATIONAssociation House235 Ash RoadAldershotHants GU12 4DDTel: 01252 321302www.concreterepair.org.uk

THE CONCRETE SOCIETYTelford AvenueCrowthorneBerkshireRG45 6YSTel: 01344 466007www.concrete.org.uk

CIRIAConstruction Industry Research

& Information Association6 Storey's GateWestminsterLondon SW1P 3AUTel: 020 7222 8891www.ciria.org.uk

CORROSION PREVENTION ASSOCIATIONAssociation House235 Ash RoadAldershotHants GU12 4DDTel: 01252 321302www.corrosionprevention.org.uk

INSTITUTE OF CORROSION4 Leck HouseLake StreetLeighton BuzzardBeds LU7 7TQTel: 01525 851771www.icorr.demon.uk

INSTITUTION OF CIVILENGINEERSGreat George StreetLondon SW1P 3AATel: 020 7222 7722www.ice.org.uk

INSTITUTION OF HIGHWAYS& TRANSPORTATION6 Endsleigh StreetLondon SW1H 0DZTel: 020 7387 2525www.iht.org

INSTITUTE OF MATERIALS1 Carlton House TerraceLondon SW1Y 5DBTel: 020 7839 4071www.materials.org.uk

INSTITUTION OFROYAL ENGINEERSBrompton BarracksChathamKent ME4 4UGTel: 01634 842669

INSTITUTION OFSTRUCTURAL ENGINEERS11 Upper Belgrave StreetLondon SW1X 8BHTel: 020 7235 4535www.istructe.org.uk

INTERPAVEConcrete Block Paving Association60 Charles StreetLeicester LE1 1FBTel: 0116 253 6161www.paving.org.uk

MORTAR INDUSTRYASSOCIATION156 Buckingham Palace RoadLondonSW1W 9TRTel: 020 7730 8194www.mortar.org.uk

QUARRY PRODUCTSASSOCIATION156 Buckingham Palace RoadLondon SW1W 9TRTel: 020 7730 8194www.qpa.org

QSRMCQuality Scheme for ReadyMixed Concrete3 High StreetHamptonMiddlesex TW12 2SQTel: 020 8941 0273

RIBARoyal Institute of British Architects66 Portland PlaceLondon W1N 4ADTel: 020 7580 5533www.architecture.com

CEMENTITIOUS SLAGMANUFACTURERS ASSOCIATIONCroudace HouseGoldstone RoadCaterhamSurrey CR3 6XQTel: 01883 331071

SOCIETY OF CHEMICALINDUSTRY14/15 Belgrave SquareLondon SW1X 8PSTel: 020 7235 3681www.sci.mond.org

UNITED KINGDOMACCREDITATION SERVICE21-47 High StreetFelthamMiddlesexTel: 020 8917 8400www.ukas.org.uk

UNITED KINGDOM CAST STONE ASSOCIATIONCentury HouseTelford AvenueCrowthorneBerks RG45 6YSTel: 01344 762676www.ukcsa.co.uk

UNITED KINGDOM QUALITY ASH ASSOCIATIONRegent HouseBath AvenueWolverhamptonWV1 4EGTel: 0102 576 586

Yearbook: 2000-2001

CONCRETE TECHNOLOGYINSTITUTE OF

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INSTITUTE OF CONCRETE TECHNOLOGYP.O.BOX 7827, Crowthorne, Berks, RG45 6FR

Tel/Fax: (01344) 752096Email: ict@ictech.org

Website: www.ictech.org

THE ICTThe Institute of Concrete Technology was

formed in 1972 from the Association ofConcrete Technologists. Full membership isopen to all those who have obtained theDiploma in Advanced Concrete Technology.The Institute is internationally recognised andthe Diploma has world-wide acceptance asthe leading qualification in concretetechnology. The Institute sets higheducational standards and requires itsmembers to abide by a Code of ProfessionalConduct, thus enhancing the profession ofconcrete technology.

AIMSThe Institute aims to promote concrete

technology as a recognised discipline and toconsolidate the professional status ofpractising concrete technologists.

PROFESSIONAL ACTIVITIESIt is the Institute's policy to stimulate

research and encourage the publication offindings and to promote communicationbetween academic and commercialorganisations. The ICT Annual Conventionincludes a Technical Symposium on a subject oftopical interest and these symposia are wellattended both by members and non-members. Many other technical meetings areheld. The Institute is represented on a numberof committees formulating National andInternational Standards and dealing with policymatters at the highest level. The Institute isalso actively involved in the education andtraining of personnel in the concrete industryand those entering the profession of concretetechnologist.