pzz326 - trl.co.uk ~l the transport research laboratory is an executive agency of the department...
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Iby Andrew S Smith and Ansel C Dunham(University of Leicester)
Ih exed~ WV ofJiTHE DEPARTMENTOF TRANSPORT--- Contractor Report 291
The Transport Research Laboratory is an executive agency of the Department ofTransport. It provides technical help and advice based on research to enable theGovernment to set standards for highway and vehicle design, to formulatepolicies on road safety, transport and the environment, and to encourage goodtraffic engineering practice.
TRL also sells its services, acting as contractor, consultant or providing facilitiesandstaff ona fee-paying basis for customers in the private sector.
TRUs expertise ranges from the construction of highways, bridges andtunnels, toall forms ofroad safety, traffic control and driver behaviour.
For instance, highways and structures research at TRL develops improvedmaterials and methods which enable earthworks, roads and bridges to bedesigned, built and maintained more cost-effectively. New ways of reinforcingearth can cut construction costs, while bridges can be modified to reducecorrosion. Road surfaces developed at TRL can reduce noise and cut wet-weatherroad spray from lorries by 90 per cent.
Safety research varies from monitoring the incidence of drinking and driving anddevising ways of reducing it, to improving junction designs and cooperating withEuropean partners on new standards for improved impact protection in vehicles.
Traffic research seeks to make the most of existing roads by, for instance,improving traffic signal coordination and devising systems which help driversavoid congestion. Other research looks at the effectiveness of parking controlsand improved crossings for pedestrians.
TRL research informs Government transport policy by studying, for example, theeffects of bus deregulation and how land use interacts with the road and railtransport system.
TRL employs around 600 scientists, engineers and support staff and is headed by aChief Executive. Its headquarters are at Crowthorne, Berkshire where its facilitiesinclude a 3.8km test track, a separate self-contained road network, a structures hallwhere bridge structures can be stressed to breaking point, a facility for carrying outaccelerated tests on road structures and advanced computer systems which areused to develop sophisticated traffic control programs. A Scottish section inLivingston provides advice to highway authorities on local problems such as rockengineering, bridges, road construction and maintenance.
A large proportion of the research is sub-contracted to industry, consultants anduniversities. The Laboratory also collaborates with local authorities and otherorganisations within Europe and elsewhere. In addition, TRL expertise isprovided to developing countries as part of Britains overseas aid programme.
For more information: TRL Public Relations, 0344770587
Department of Transpofi+Zak
Contratior Report 291
ALWLI-SILICA-REACTION IN CONCRETE: A SURVEY OF UNDULATORYEXTINCTION OF QUAR~ IN GRANITES AND SANDSTONES
by Andrew S Smith and Ansel C Dunham(Industrial Mineralogy Unit, Depatiment of Geology, University of Leicester)
Copyright tintroller HMSO 1992. The views expressed in this pubihtion are not naessari~thoseof theDepartment of Transport. ~racts from the text maybe reprodwed, exapt for mmmemial pupses,provided the soum is achowledged. The wok de=ribed was =rried out undera mntract placed on theUniversity of Lekester by TRL.
The wok de~ribed in this repo~ forms part of a Se~m Reseamh Proj~ (DDRW) funded reseamhprogramme mndtied by the Transport Reseamh Laborato~.
Highways Resource Centre
Transport Research Laborato~
Old Wokingham Road
CroMhorne, BerkshireRG11 6AU
Undulato~ Extinction of Quati in Granites and Sandstones 1
THE ALWLI-SILICA REACTION; the role of strained quati3.1. The Reaction
UNDUUTORY ~lNCTION IN QUAR~4.1, Introduction4.2. Previous Work4.3. Undulatory Extinction Measurements: Flat Stage or Univer~ Stage?
4,3,1. Theoretical Evaluation
THE MECHANICS OF QUAR~ DEFORMATION
SAMPLE COLLECTION6.1. S.W.England6.2, Wales6.3. hke District6.4. Pennines6,5, Scotland6,6. Sampling Technique
METHODS FOR MEASURING UNDUUTORY EXTINCTION IN QUAR~7.1. Introduction
7.1.1. Universal Stage Method7.1.2. DeHills/Cowalhn Method7.1.3. Dolar-Mantuani Method7.1.4. AU~ Extinction point - extinction point on the universal stage7.1.5. ROTA Extinction point - extinction point on the flat stage7.1.6. Test of reproducibility of the measurement of the apparentundulato~ extinction angles, and the Dolar-Mantuani methodof measurement of strain in quati grains
22.214.171.124. Introduction126.96.36.199. Data7.1,6.3. Discussion188.8.131.52. Relation beWeen the apparent undulatoryextinction angle and the Dolar-Mantuaniextinction angle184.108.40.206. Universal stage measurements220.127.116.11. Conclusions
7.2. Results7.2.1. Summary of findings
7.3. Other methods of investigation7,3.1. Point counting7.3.2. X-ray diffraction broadening
QUAR~ GRAIN TEXTURAL CHARACTERISTICS8.1. Introduction8.2. Quati grain textures of milected samples8.3. Results
Undulato~ Mnction of Quartz in Granites and Sandstones 2
9.1. Conclusions of the survey9.2. Suitability of the Concrete Society guide-lines
10.0 AUTHORS RECOMMENDAmONS
Appendix Al .0. Undulatory extindion measurement promduresAl. 1. Universal stage methodAl .2. AUEA methodAl .3. DeHills/Cowal~n methodAl .4, Dolar-Mantuani methodAl .5. ROTA method
Appendix A2.0, Point count data and undulatory extintiion measurement statisti~
Appendix A3,0. Crystallite size determination from x-ray line broadening
Appendix A4,0. Samples
Appendix A5,0, Terminology
Undulatory Extinction of Quartz in Granites and Sandstones 3
Undulatory extinction in quartz is a wide spread feature found in many different rock types. Thedegree of undulosi~ exhibited is a function of the processes of rock formation and deformation. Asundulosity suggests a level of instability of the qu-, the degree of undulosity has been used, for sometime, to indicate the potential reactivity of the quartz in the alkali-silica reaction. The method of routinemeasurement of the degree of undulosity, on investigation, has been found to be inaccurate. A newmethod for this routine measurement is proposed, utilising the universal stage. assembly fixed to ametrological microscope, Instability of quartz grains can also be gauged by the assessment of graintextures, and grain and crystallite sizes, Textures and grain size are classified by the visual featuresexhibited when the grains are viewed using a metrological microscope, whilst c~stallite size is measuredby the use of X-ray diffraction line broadening techniques. hdysis of a number of quartz-bearing rocktypes; mainly granites, gneisses, schists, porphyrites, and sandstones, from different parts of GreatBritain has been carried out. The results indicate that if atl these features are investigated and quantifiedthen it is possible to classify the stability of the quartz, eg. a mean true undulato~ extinction value of >5degrees would be classed as highly strained, and therefore assess the potential for reaction in thealkali-silica reaction.
Undulatory extinction in quartz is believed to result from strain within individual grains, causingdifferent parts of the original crystal to have slightly different orientations. The boundaries betweendifferent areas are sometimes diffuse or can be relatively sharp; both are probable areas of highdislocation densities. This structural mismatch within original grains means that there is more internalenergy present, tiich means that the quartz is more chemically reactive. Hence, it is possible that suchquadz could react with the alkalies in concrete to form the deleterious gel responsible for the expansionfound in concrete structures. The reaction is known as the alkali-silica reaction,
Strained quartz is known from a number of different types of geological environment; granitesand other quartz bearing igneous rocks, sediments derived from such rocks and metaquatizites formedby metamorphism.
The purpose of this project is to investigate the distribution of strained quartz-bearing rocks inGreat Britain, and the method of measurement, with particular reference to those that are or might beused for concrete aggregates. The investigation is conducted in the light of suggestions made in theConcrete Societys Technical Repod No.
3.0. THE ALWU-SIUCA REACTION;
The atkali-silica reaction (ASR),
the role of strained quati
also known as concrete cancer, has, since the 1930s been aproblem in the construction industry. Since its identification in the late 1930s by Stanton (1940), ASRresearch has provided indust~ with a lot of possible methods of identi~lng, and even preventing thereaction taking place in concrete structures.
3.1. The Reaction
The reaction in question is one of the three Nkali-Aggregate Reactions, that take place inconcrete. These are:-
Undulato~ Mnction of Quati in Granites and