brna-sp-cs-012-03 - concrete

CORPORATE REFERENCE DOCUMENT

STANDARD SPECIFICATION

FOR

CONCRETE

Document Number : BRNA-SP-CS-012-03

NOTE

This document contains proprietary information belonging to Brown & Root NA Ltd.

It may neither be wholly or partially reproduced without the prior written permission

of Brown & Root NA Ltd.

Users of this document must always consult the appointed Custodian for advice. The

Custodian should be notified of any errors, omissions and suggested improvements.

BROWN & ROOT NA LTD DOC. NO.: BRNA-SP-CS-012-03

STANDARD SPECIFICATION FOR

CONCRETE PAGE 1 OF 53

_________________________________________________________________________________

BRNA-SP-CS-012-03 April, 01

TABLE OF CONTENTS

Page No.

TABLE OF CONTENTS ....................................................................................................... 1

1.0 INTRODUCTION ...................................................................................................... 2

2.0 SCOPE ......................................................................................................................... 2

3.0 DEFINITIONS ........................................................................................................... 2

4.0 REGULATIONS CODES AND STANDARDS ...................................................... 2

5.0 OTHER REFERENCE DOCUMENTS ................................................................. 4

6.0 TECHNICAL REQUIREMENTS .......................................................................... 5

6.1 Materials ..................................................................................................................... 5

6.2 Storage of Materials .................................................................................................. 7

6.3 Concrete Properties ................................................................................................... 9

6.4 Concrete Mix Design ................................................................................................. 12

6.5 Quality Control and Testing ..................................................................................... 14

6.6 Batching, Mixing and Transporting Concrete ........................................................ 27

6.7 Formwork ................................................................................................................... 30

6.8 Reinforcement ............................................................................................................ 33

6.9 Built-in Items, Holes and Cavities ............................................................................ 34

6.10 Concreting .................................................................................................................. 35

6.11 Curing and Protection of Concrete .......................................................................... 42

6.12 Surface Treatment and Remedial Work ................................................................. 44

6.13 Concrete Finishes ....................................................................................................... 46

6.14 Corrosion Protection of Concrete ............................................................................ 48

6.15 Precast Concrete Flags, Kerbs Etc ........................................................................... 51

6.16 Setting Base Plates and Beams Plates ...................................................................... 51

7.0 DOCUMENTATION TO BE SUBMITTED .......................................................... 52




_________________________________________________________________________________


1.0 INTRODUCTION

This Standard Technical Specification specifies the minimum technical requirements for

materials and workmanship of concrete Works.

2.0 SCOPE

The scope shall comprise provision and storage of materials, mixing, transporting, placing,

curing and testing of concrete with the exception of concrete for Prestressed Concrete

Cylinder Pipes (PCCP).

3.0 DEFINITIONS

None required.

4.0 REGULATIONS, CODES AND STANDARDS

Unless indicated otherwise in this Specification, the requirements of the following

regulations, codes and standards shall apply:-

American Society for Testing and Materials (ASTM)

ASTM C 29/C 29M Standard Test Method for Bulky Density ("Unit Weight") and Voids

in Aggregate.

ASTM C 33 Standard Specification for Concrete Aggregates.

ASTM C 40 Standard Test Method for Organic Impurities in Fine Aggregates for

Concrete.

ASTM C 117 Standard Test Method for Material Finer Than 75 Microns (Nr. 200)

Sieve in Mineral Aggregates by Washing.

ASTM C 123 Standard Test Method for Lightweight Particles in Aggregate.

ASTM C 127 Standard Test Method for Specific Gravity and Absorption of Coarse

Aggregate.

ASTM C 128 Standard Test Method for Specific Gravity and Absorption of Fine

Aggregate.

ASTM C 131 Standard Test Method for Resistance to Degradation of Small-size

Coarse Aggregate by Abrasion and Impact in the Los Angeles

Machine.




_________________________________________________________________________________


ASTM C 142 Standard Test Method for Clay Lumps and Friable Particles in

Aggregates.

ASTM C 150 Standard Specification for Portland Cement.

ASTM C 227 Standard Test Method for Potential Alkali Reactivity of Cement-

aggregate Combinations (Mortar-bar Method).

ASTM C 289 Standard Test Method for Potential Alkali-Silica Reactivity of

Aggregates (Chemical Method).

ASTM C 295 Standard Guide for Petrographic Examination of Aggregates for

Concrete.

ASTM C 309 Standard Specification for Liquid Membrane-Forming Compounds

for Curing Concrete.

ASTM C 586 Standard Test Method for Potential Alkali Reactivity of Carbonate

Rocks for Concrete Aggregates (Rock Cylinder Method).

ASTM C 685 Standard Specification for Concrete Made by Volumetric Batching

and Continuous Mixing.

ASTM C 920 Standard Specification for Elastomeric Joint Sealants.

ASTM C 1105 Standard Test Method for Length of Change of Concrete Due to

Alkali-Carbonate Rock Reaction.

ASTM D 1190 Standard Specification for Concrete Joint Sealer, Hot-Applied

Elastic Type.

ASTM D 1751 Standard Specification for Preformed Expansion Joint Fillers for

Concrete Paving and Structural Construction (Non-extruding and

Resilient Bituminous Types).

ASTM D 1752 Standard Specification for Preformed Sponge Rubber and Cork

Expansion Joint Fillers for Concrete Paving and Structural

Construction.

British Standards Institution (BSI)

BS 12 Specification for Portland Cement.

BS 812 Testing Aggregates.

BS 882 Specification for Aggregates from Natural Sources for Concrete.

BS 1305 Specification for Batch Type Concrete Mixers.

BS 1377 Methods of Test for Soils for Civil Engineering Purposes.

BS 1881 Testing Concrete.

BS 3148 Methods of Test for Water for Making Concrete (Including Notes on

the Suitability of the Water).




_________________________________________________________________________________


BS 3963 Method for Testing the Mixing Performance of Concrete Mixers.

BS 4016 Specification for Flexible Building Membranes (Breather Type).

BS 4449 Specification for Carbon Steel Bars for the Reinforcement of

Concrete.

BS 4483 Specification for Steel Fabric for the Reinforcement of Concrete.

BS 4550 Methods of Testing Cement.

BS 5075 Concrete Admixtures.

BS 5328 Concrete. Part 1: 1997. Guide to Specifying Concrete.

BS 5606 Guide to Accuracy in Building.

BS 5975 Code of Practice for Falsework.

BS 7263 Precast Concrete Flags, Kerbs, Channels, Edgings and Quadrant.

BS 8007 Code of Practice for Design Of Concrete Structures for Retaining

Aqueous Liquids.

BS 8110 Structural Use of Concrete.

BS 8666 Specification for Scheduling, Dimensions, Bending and Cutting of

Steel Reinforcement of Concrete.

BS EN ISO 4066 Construction Drawings. Bar Scheduling.

5.0 OTHER REFERENCE DOCUMENTS

Other relevant Specifications and documents referenced herein are listed below:-

American Concrete Institute (ACI)

ACI 207R Mass Concrete, Part 1 and Effect of Restraint, Volume Change, and

Reinforcement on Cracking of Mass Concrete, Part 2.

ACI 224R Control of Cracking in Concrete Structures.

ACI 304R Guide for Measuring, Mixing, Transporting and Placing Concrete.

ACI 305R Hot Weather Concreting.

ACI 308 Standard Practice for Curing Concrete.

ACI 309R Guide for Consolidation of Concrete.

ACI 347R Guide to Formwork for Concrete.

Brown & Root NA (BRNA)

BRNA-SP-MT-003 Standard Specification for Coatings and Linings.




_________________________________________________________________________________


BRNA-SP-MT-005 Standard Specification for the Corrosion Protection of Buried

Concrete Structures.

Construction Industry Research and Information Association (CIRIA)

CIRIA Report 91 Early-age Thermal Crack Control in Concrete.

U.S. Corps Of Engineers (CRD)

CRD-C513 Rubber Waterstops.

CRD-C572 Polyvinyl Chloride Waterstops.

CRD-C621 Non Shrink Grout.

6.0 TECHNICAL REQUIREMENTS

6.1 Materials

6.1.1 Materials

Approved samples of all materials shall be kept in suitable containers, properly

labelled and stored on site for reference.

6.1.2 Cement

Ordinary Portland cement (OPC) shall comply with BS 12 or ASTM C 150, Type II.

OPC shall be used for all reinforced concrete. Tanking as specified in Section 6.14

shall be provided for all buried structures.

OPC shall be used for all mass concrete. The classification of sulphate exposure

given in Table 7 of BS 5328 : Part 1 shall be used as a guide:

Class 1 and 2 : OPC without tanking

Class 3, 4, and 5 : OPC with tanking

The above requirements do not apply to mass concrete used for non-structural

purposes.




_________________________________________________________________________________


Any cement which is lumpy or partially set shall be rejected and removed from the

site.

6.1.3 Aggregates

Fine and coarse aggregates shall be as defined by and be of the quality, shape and

nature required by BS 882. Potential alkali reactivity of aggregates shall be

determined in accordance with ASTM C 295, ASTM C 289, and ASTM C 586.

The moisture content of the aggregates shall be determined in accordance with BS

812: Part 2.

The grading of aggregates shall be as follows:

(a) Coarse Aggregate

Aggregates shall be graded according to the recommendations of BS 882,

Table 4:

• 10 millimetres maximum size, for screed finishes and small

components.

• 20 millimetres maximum size for all prestressed, reinforced and

precast concrete, benching, no-fines concrete and blinding concrete.

• 40 millimetres maximum size for all mass concrete.

(b) Fine Aggregate

Fine aggregates shall conform to BS 882, Table 5.

6.1.4 Water

Water used for mixing and curing concrete shall meet the requirements of BS 3148.




_________________________________________________________________________________


6.1.5 Concrete Admixtures

(a) General

Before approval for the use of any admixture is given Contractor shall prove

its suitability for the work and its compatibility with the cement it is intended

to complement.

Only admixtures which can be administered in fixed calibrated amounts

through a mechanical dispenser or cachet, and which are added directly to

the mixing water shall be permitted.

Where more than one type of admixture is to be used for the same concrete

mix, each shall be dispensed separately.

(b) Water-reducing admixtures

Where, in the opinion of Owner, the workability of the mix is inadequate to

achieve an acceptable compaction and/or surface finish, or where excessive

bleeding of the concrete is in evidence, a water-reducing or high range water

reducing admixture complying with BS 5075 shall be used.

(c) Set-retarding admixtures

Where large quantities of concrete are to be placed at any one time or where

concreting is undertaken under hot weather conditions, Contractor may

include an approved set-retarding admixture to enable work to be properly

finished before premature setting has taken place. The admixture shall

comply with the requirements of BS 5075: Part 1.

(d) Admixtures containing chloride

Admixtures containing chloride shall not be used.

(e) Air-entraining admixtures

Air-entraining admixtures shall be in accordance with the requirements of BS

5075: Part 2.




_________________________________________________________________________________


6.1.6 Reinforcing Steel

Reinforcement shall be either carbon steel bars conforming to BS 4449, or fabric

reinforcement conforming to BS 4483.

6.2 Storage of Materials

6.2.1 Cement

Cement shall be stored in a weatherproof building, bins or silos which shall exclude

moisture and contaminants. Cements of different types shall be stored separately.

Cement shall be fresh when delivered to site and the consignments shall be used in

the order of their delivery. Contractor shall mark the date of delivery on each

consignment and each consignment shall be stored separately and in such a manner

as to be easily accessible and identifiable.

Bagged cement shall not be stored higher than 10 bags at a temperature of not less

than 8°C. Bags shall be placed on dry boards above the floor. No bags of cement

shall be used unless the manufacturer's seals are intact at the time of mixing.

6.2.2 Aggregate

Aggregate stockpiles shall conform to the provisions of ACI 304R and be maintained

in a manner to avoid excessive segregation and to prevent contamination with other

materials or aggregates of different sizes.

The aggregates of various sizes shall be kept separate and away from all possible

contamination and shall be stored on a hard-standing area laid to falls or in bins,

provided with proper drainage.

Stockpiles shall be at least 2m in height and built in layers of not more than 1m in

thickness. No layer shall be allowed to 'cone' down over the under layer.

If aggregates of difference gradings are stockpiled in close proximity the stockpiles

shall be separated by bulkheads.




_________________________________________________________________________________


All aggregates shall be handled from the stockpile or other source to the batching

plant in such a manner as to secure a typical grading of the material, care being taken

to avoid crushing the aggregates and that they remain free from extraneous matter.

All aggregates produced or handled by hydraulic methods and all washed aggregates

shall be stockpiled for draining at least 24 hours before being batched.

6.2.3 Reinforcing Steel

Reinforcing steel shall be stored on supports clear off hard laid floors in covered

areas with a waterproof overhead cover to screen stocks from contamination from

windblown dust. Delivery and storage shall be organised in such a manner as to

make identification easy. Supports shall be such that distortion of bars is avoided

and contamination and corrosion prevented.

Individual bundles of reinforcing bars shall be durably marked to identify source,

batch number, type and diameter.

Any reinforcement which becomes contaminated shall be sandblasted with clean

sand, and washed if necessary, not earlier than 3 days before its incorporation in the

Works.

6.2.4 Other Materials

Other materials shall be stored in such a manner as to avoid contamination and

deterioration and where a manufacturer's product is to be used any specific

recommendation regarding its storage shall be complied with.

6.3 Concrete Properties

6.3.1 General

All concrete, except where otherwise specified by Owner, shall comply with the

relevant provisions of BS 5328. Concrete for water retaining structures shall be in

accordance with BS 8007. Design of normal concrete shall be to BS 8110. The

grades of concrete appropriate for specific use shall, unless specified otherwise, be

selected from the preferred grades in BS 5328 which are adequate on grounds of




_________________________________________________________________________________


strength and durability. As a guide the characteristic strength (fcu) for the concrete

elements shall, as a minimum, be as follows:

• Grade 40 - Prestressed concrete.

• Grade 30 - Reinforced concrete, precast concrete.

• Grade 20 - Mass concrete, floor screeds, benching.

• Grade 15 - Blinding concrete.

The meaning of the terms "grade" and "characteristic strength" is as defined in BS

5328.

6.3.2 Durability

The minimum cement contents shall be as follows:

• 360 kg/m³ of cement - for Grades 40, 30 and 20 concrete.

• 250 kg/m³ of cement - for Grade 15 concrete.

The maximum water/cement ratio for Grade 40 concrete shall be 0.40, for Grade 30

and 20 concrete shall be 0.45, and for Grade 15 concrete shall be 0.5.

In all cases of mix proportioning, the quantity of added water shall take account of

the moisture contained in the aggregates and shall be the minimum consistent with

the workability requirements.

6.3.3 Thermal Crack Control

In the first instance the thermal crack control shall be by means of the concrete mix

design and subsequently by the construction practice especially curing and protection

from drying. Note shall be taken of ACI 224R.

Where structural integrity of mass concrete element is likely to be impaired the

control of cracking shall be by provision of reinforcement. The amount of

reinforcement shall follow the recommendations of ACI 207R and CIRIA Report 91 -

"Early-age thermal crack control in concrete".




_________________________________________________________________________________


6.3.4 Workability

For walls, columns, suspended slabs and beams, and grade beams the slump shall be

between 50 millimetres and 100 millimetres unless a high range water reducer is

approved for use, in which case the slump shall be between 150 millimetres and 200

millimetres.

For slabs cast against blinding or no-fines concrete and for foundations the slump

shall be between 50 millimetres and 100 millimetres unless a high range water

reducer is approved for use in which case the slump shall be between 125 millimetres

and 200 millimetres.

6.3.5 Air Content

All concrete shall have an air content of 4.5 + 1.5 percent.

6.3.6 Chloride Content

The maximum chloride ion content in the concrete resulting from the contribution of

the mix ingredients including water, aggregates, cement and admixtures shall be as

follows:-

Type of concrete Maximum chloride ion content

(percent by weight of cement)

Prestressed concrete 0.06

Reinforced concrete 0.10

Concrete with no embedded steel (mass

concrete, floor screeds, benching and

blinding)

0.60

6.3.7 Sulphate Content

The maximum sulphate content in the concrete, resulting from the contribution of the

mix ingredients including water, aggregates, cement and admixtures for all types of

concrete shall be 4.0 percent (S03) by weight of cement.




_________________________________________________________________________________


6.3.8 No-Fines Concrete

Aggregate shall be 20 millimetres to 10 millimetres graded with no more than 5%

passing 10 millimetre sieve. Only sufficient water shall be added to ensure complete

coating of aggregate. One half of this water shall be placed into the mixer first, after

which the aggregate and cement shall be admitted. After partial mixing the balance

of the water shall be added until a consistent mix is achieved.

6.4 Concrete Mix Design

6.4.1 General

Contractor shall submit for Owner approval details of the proposed concrete mixes

including proportions of all materials, intended compacting factor, the average

strength to be attained in trial mixes and a target standard deviation. Following

approval the proposed mixes shall be used for carrying out laboratory trials. Subject

to any modifications agreed as necessary as a result of the laboratory trials,

Contractor shall carry out site trials on each mix under full scale production

conditions. The mix proportions resulting from site trials shall, subject to approval,

be used for constructing the Works.

6.4.2 Laboratory Trials

Contractor shall produce in the laboratory two batches from a trial mix for each grade

of concrete using cement and surface dry aggregates typical of the proposed source

of supply. Each batch shall contain the correct amount of cement and have a free

water/cement ratio at or below the maximum value. The workability of each batch

shall be determined. Provided that the slumps obtained fall within the specified

limits, and the requirements regarding cement content and free water cement ratio

have been met, Contractor may proceed to carry out site trials. For the purpose of

determining target mean strength of the concrete a design margin shall be added to

the characteristic strength for the particular grade of concrete. This design margin

shall not be less than 10N/mm².




_________________________________________________________________________________


6.4.3 Site Trials

Trial mixes shall be made at site under full scale production conditions. The

proportions of materials used, including the water content and any admixtures, shall

agree with the mix proportions determined by the laboratory trial mixes. Three

batches of concrete for each grade of concrete shall be produced, using the same

plant and mixing time proposed by Contractor for use in the Works.

For each grade of concrete the following shall be carried out:

• The workability of each of the three batches shall be determined immediately

after mixing by the slump test specified in BS 1881: Part 102 or compacting

factor in BS 1881: Part 103 as appropriate.

• Two (a pair) test cubes or cylinders from each of the three batches shall be

made, cured, stored and tested at seven (7) days and twenty-eight (28) days

after casting in accordance with the method described in BS 1881.

The relationship between cube and cylinder strength shall be as stated in Section

6.5.7.

A site trial mix for a particular grade and type of concrete shall be considered

satisfactory provided that:

i. The slumps fall within the specified limits, and

ii. none of the strengths of the test specimens is below the specified

characteristic strength,

or

iii. the average value of the three consecutive test results taken from the trial mix

is equal to or greater than the target mean strength, and

iv. the difference in strength between two test specimens divided by their mean

value does not exceed 15%,

where a test result is the average of two (pair) test specimens.




_________________________________________________________________________________


If the results for any mix meet these requirements and the mix complies with all other

specified concrete properties, the mix will then be approved for use in the Works.

If the results for any mix fail to meet these requirements Contractor shall re-design

that mix and make further site trials as above.

6.5 Quality Control and Testing

6.5.1 General

Quality control charts shall be prepared and maintained as a record of all the concrete

testing activities undertaken. These charts shall, where applicable, show the extreme

limits of acceptable values and all test results whether within or outside the

acceptable limits. Quality control charts shall be prepared and submitted on a weekly

basis.

6.5.2 Cement

Cement shall be sampled and tested at the manufacturing plant in accordance with

the requirements of BS 4550. A test certificate shall be provided with each delivery

of cement to the site. Additionally, any cement which has been stored on the site in

bags for 3 or more months, or stored in bulk for 6 or more months shall be sampled

and the samples tested for compliance with this Specification.

Any cement failing to meet the requirements of this Specification shall be rejected

and removed from the site.

6.5.3 Aggregates

Aggregates shall be sampled and tested as specified.

The tests shown in Table 6.1 shall be carried out at the stated frequencies at the

aggregate production plant.

The tests shown in Table 6.2 shall be carried out at the stated frequencies at the

concrete batching plant.




_________________________________________________________________________________


The following action shall be taken if the test results fail to conform with

requirements of this specification.

(a) Fine Aggregate

(i) Grading

Where the amount retained on any sieve is outside the range of acceptable

values in BS 882, the fine aggregate shall be re-sampled and re-tested. If the

second test results in values outside those limits the stockpiles shall be

rejected, removed from the aggregate storage area and replaced with material

conforming to the Specifications.

(ii) Moisture Content

When the moisture content of the fine aggregate changes by 0.5% or more,

the concrete batching plant scale settings for fine aggregate and water shall

be adjusted either directly or by means of a moisture compensation device.

(iii) Contamination by Chemicals

Where the chemical contents are outside the ranges shown in Table 6.2 the

aggregate stored at the batching plant shall be either washed until the

chemical content requirements are met, or removed and replaced by material

conforming to this Specification.

(b) Coarse Aggregate

(i) Grading

When the amount passing any sieve is outside the specified limits, the coarse

aggregate shall be re-sampled and re-tested. If the second sample fails to

meet the required limits, the material stockpiled shall be removed from the

aggregate storage area and replaced with material conforming to this

Specification.




_________________________________________________________________________________


(ii) Moisture content

The test results and remedial actions for coarse aggregate shall be treated in

the same way as for fine aggregate with the proviso that, if the variation in

water content results in the specified water/cement ratio being exceeded, the

in-situ concrete strength of batches placed before the adjustment shall be

sampled and tested in accordance with BS 1881: Part 120.

Notwithstanding the results of this test, as soon as it is determined that the

maximum water/cement ratio defined in this Specification has been

exceeded, concrete work shall cease until full compliance with this

Specification is achieved.

(iii) Particle shape

If the sample tested does not conform to the requirements of BS 812: Part

105, Section 105.1 another sample shall be taken and tested. If this sample

fails, the material stockpiled shall be removed from the aggregate storage

area and replaced with material conforming to this Specification.

(iv) Contamination by Chemicals

Where the chemical contents are outside the ranges shown in Table 6.2 the

aggregate stored at the batching plant shall be either washed until the

chemical content requirements are met, or removed and replaced by material

conforming to this Specification.




_________________________________________________________________________________


TABLE 6.1

TESTS FOR AGGREGATES AT THE PRODUCTION PLANT

Test Code or

Name

Test Description

Test Requirements

Minimum Frequency

ASTM C 127

Specific gravity and

absorption of coarse

aggregate

Coarse agg.: Min. bulk saturated

surface dry (ssd) specific gravity

2.4, max. absorption 2.5%

1/1000T (Once per

1000 tonnes used - or

part thereof produced)

ASTM C 128

Specific gravity and

absorption of fine

aggregate

Fine agg.: Min. bulk ssd specific

gravity 2.4, max. absorption

1.8%

1/1000T or part

thereof

ASTM C 142

Clay lumps and friable

particles

With chert:

Fine aggregate: max. 5.0%

Coarse aggregate: max. 5.0%

Without chert:

Fine aggregate: max. 3.0%

Coarse aggregate: max. 3.0%

1/500T or part thereof

BS 812:

Part 105

Flakiness index

Elongation index

(Coarse aggregate)

15% Max.

15% Max.

1/1000T or part

thereof




_________________________________________________________________________________


TABLE 6.1 (continued)


Test Code or

Name

Test Description

Test Requirements

Minimum Frequency

ASTM C 29/

C 29M

Weight and voids in

aggregate

Results used for determining

concrete mix design

1/2000T or part

thereof

BS 812:

Part 121

Soundness of

Aggregate by use of

sodium sulphate or

magnesium sulphate

Use of magnesium sulphate:

Fine aggregate: Max. 18%

Coarse aggregate: Max. 18%

1/1000T or part

therefore

ASTM C 131

Resistance to

Degradation of small-

size coarse aggregate

by abrasion and

impact in the Los

Angeles machine

Coarse aggregate: Max. 50% at

500 revolutions

1/2000T or part

thereof

BS 812:

Part 118

Sulphate content

Max. 0.4%





_________________________________________________________________________________




Test Code or

Name

Test Description

Test Requirements

Minimum Frequency

BS 812:

Part 117,

Appendix C

Chloride content

Fine aggregate: Max. 0.012%


ASTM C 289

Potential reactivity of

aggregate (Chemical

method)

ASTM C 33, Sections 7.3 and

11.2

1/2000T or part

thereof

ASTM C 586

Potential alkali

reactivity of carbonate

rocks for concrete

aggregates (rock

cylinder method)


11.2

1/2000T or part

thereof

Quantab test

strips

"Quick" chloride

content


Coarse aggregate: Max. 0.005%


ASTM C 295

Petrographic

examination of

aggregates for

concrete


11.2

Once at start of each

aggregate source




_________________________________________________________________________________




Test Code or

Name

Test Description

Test Requirements

Minimum Frequency

ASTM C 227

Potential alkali

reactivity of cement-

aggregate

combinations (mortar

bar method)

ASTM C 33 Sec. 7.3 and 11.2


aggregate source

ASTM C 1105

Length change of

concrete due to alkali-

carbonate rock

reaction

ASTM C33 Sec. 7.3 and 11.2


aggregate source

ASTM C 117 Material finer than nr

200 sieve in mineral

aggregate by washing

Fine aggregate: 3.0% Max.

Coarse aggregate: 1.0% Max.


BS 812:

Part 103

Sieve or screen

analysis fine and

coarse aggregate

BS 882: Tables 4 (coarse) and 5

(Fine)





_________________________________________________________________________________




Test Code or

Name

Test Description

Test Requirements

Minimum Frequency

ASTM C 40

Organic impurities in

fine aggregate for

concrete

ASTM C 33, Sec. 6.2

1/1000T of part

thereof

ASTM C 123

Light weight pieces in

aggregate

Fine aggregate: Max. coal and

lignite 1.0% per ASTM C 33,

Sec. 11.1.8

Coarse aggregate: Max. coal

and lignite 0.5% per ASTM C33,

Sec. 11.1.8

1/1000T or part

thereof




_________________________________________________________________________________


TABLE 6.2

TESTS FOR AGGREGATES AT THE CONCRETE BATCHING PLANT

Test Code or

Name

Test Description

Test Requirements

Minimum Frequency

ASTM C 117

Material finer than

Nr 200 sieve in

mineral aggregate by

washing

Fine aggregate: 3.0% Max.

Coarse aggregate: 1.0% Max.

Once every 2 weeks

and following periods

of inclement weather

BS 812:

Part 103

Sieve or screen

Analysis fine and

coarse aggregate

Once every 2 weeks

and following periods

of inclement weather

BS 1881:

Part 118

Sulphate content

Max. 0.4%

Once per week

Quantab test

strips

"Quick" chloride

content


Coarse aggregate: Max. 0.005%

Once per week and

following periods of

inclement weather




_________________________________________________________________________________



TESTS FOR AGGREGATES AT THE CONCRETE BATCHING PLANT

Test Code or

Name

Test Description

Test Requirements

Minimum Frequency

Speedy

moisture

Moisture content

coarse and fine

aggregate (quick test)

To verify batching proportions

Daily, prior to

commencing batching

or changing weather

conditions

ASTM C 566

Total moisture content

of aggregate by drying

To verify batching proportions

Once per week and

following rain or

inclement weather




_________________________________________________________________________________


6.5.4 Water

The water used for making concrete shall be sampled and tested once per week in

accordance with BS 3148.

6.5.5 Concrete Batching Plant

The weight batching machines used shall be approved types accurate to within 2%

and shall be kept in good condition.

The accuracy of each materials’ measuring component of the batching plant shall be

checked once per week. Additionally, if the properties of the fresh concrete have

altered in a manner that could be attributed to mix proportion errors, the measuring

components shall be checked. The results of all such tests and necessary adjustments

to the plant shall be notified to Owner.

A daily concrete batching report shall be prepared and submitted to Owner detailing

the type and source of cement used, the quantities of any admixture used, the

required aggregate and water weights per cubic metre, the amount of free moisture in

each size of aggregate, the batched aggregate and water weights per cubic metre.

6.5.6 Fresh Concrete

Fresh concrete shall be sampled in accordance with BS 1881: Part 101.

(a) Slump

The slump of fresh concrete shall be tested in accordance with BS 1881: Part

102. One slump test shall be performed at the start of each individual pour

and thereafter repeated on random batches of each 50 cubic metres or part

thereof produced, or when samples for compressive strength determination

are taken, or when required by Owner.

(b) Air Content

The air content of the fresh concrete shall be determined in accordance with

BS 1881: Part 106. The frequency of sampling and testing shall be whenever




_________________________________________________________________________________


strength specimens are prepared or as required by Owner. If a single test

result is outside the limits of this Specification immediate steps shall be

taken to correct the batching of the admixture.

(c) Density of Fresh Concrete

The density of the fresh concrete shall be determined in accordance with BS

1881: Part 107 and shall be tested whenever strength specimens are prepared.

(d) Temperature

The temperature of the fresh concrete shall be taken and recorded each time a

slump test is performed or as required by Owner.

6.5.7 Concrete Strength

Samples of fresh concrete shall be taken from the batched mixes, prepared as test

cubes or cylinders, and cured and tested in accordance with BS 1881.

For the purpose of establishing cube compressive strength (based on 150mm x

150mm x 150mm cube) from cylinder compressive strength (based on 150mm

diameter x 300mm length cylinder) the following relationship shall be used:

Cube strength = cylinder strength x 1.15.

Forty samples shall be made initially in eight random samples each day for the first

five days of structural concreting of each grade of concrete. Thereafter one random

sample shall be taken from each 50 cubic metres, each individual pour, or each

individual structural element for each grade of concrete.

The test results shall be examined individually in any consecutive set of two and the

mean strength of each set calculated. Test results shall be fully in accordance with

BS 5328: Part 4, Clause 3.16.




_________________________________________________________________________________


The standard deviation shall be calculated on a continuous basis over suitable time

increments to include at least 40 results. The actual mean strength, minus 1.64 times

the standard deviation, shall be greater than the characteristic strength.

In compliance with BS 5328: Part 1, Clause 10 where the results for any mix do not

conform to the above requirements no further concrete of that mix shall be placed

until adjustments have been made to the mix proportions. Should any test result give

a strength 3 Newtons per square millimetre or more below the specified characteristic

strength, Contractor shall test the in-situ concrete in accordance with BS 1881: Part

120.

If this test conforms to the strength requirements the concrete shall be deemed

satisfactory. Should the results be less than the characteristic strength minus 3

Newtons per square millimetre the concrete shall be cut out and replaced.

6.5.8 Records of Concreting

Contractor shall submit daily returns in respect of all concrete placed during the

previous day.

The returns shall give for each location in the work:

• The position of the pour (e.g. bay or lift reference number).

• The grade of the concrete placed.

• The total volume of concrete placed and the number of batches used.

In addition, Contractor shall maintain an accurate and up to date record showing

dates, times, weather and temperature conditions when each part of the work was

concreted.

Results of all tests on concrete shall be recorded and identified with the parts of the

work to which they relate.




_________________________________________________________________________________


6.6 Batching, Mixing and Transporting Concrete

6.6.1 General

The batching, mixing and transporting of concrete shall comply with the applicable

sections of BS 1305, BS 5328, ACI 304R. The concrete batching plant shall be

capable of providing concrete at the rate necessary to comply with the construction

schedule.

6.6.2 Batch Proportions

Only with the approval of Owner shall aggregates be volume batched and in no case

shall cement be volume batched. Contractor may, however, so proportion the mix

that each batch shall use a whole bag or bags of cement, the weight of which is

known precisely. Where permission has been given for volume batching of

aggregates, all gauge boxes shall be accurate and strongly constructed and due

allowance shall be made for bulking of the aggregates in assessing the correct volume

to be used. For volumetrically batched aggregates, the provisions of ASTM C 685

shall apply.

6.6.3 Moisture Content

The batch plant shall be equipped with a moisture meter which shall accurately

indicate the moisture in the fine aggregate. The plant shall be capable of

automatically compensating for varying fine aggregate moisture content.

6.6.4 Mixing Concrete

Concrete shall be mixed in a batch type or continuous mixer tested in accordance

with BS 3963 and having a minimum performance within the limits of Table 6 of BS

1305. Continuous mixers shall be fed with materials which have been proportioned

wholly by weight. For the purpose of testing continuous mixers, one cubic metre of

concrete sampled during continuous operation shall be taken as the batch referred to

in BS 3963 and the batch capacity shall be assumed to be over 0.625m³. Concrete

mixed in batch type mixers shall be mixed for a time approved by the Owner who

will take into account the manufacturer's prototype test report and the test report for




_________________________________________________________________________________


the particular mixer for the mix proportions and the appropriate performance limits

of Table 6 of BS 1305.

The speed and rate of feed of continuous mixers shall correspond with the values on

the test report for the mix proportion and performance limits of Table 6 of BS 1305.

The drums or pans of all mixers shall revolve at the speed used for testing in

accordance with BS 3965 within a tolerance of plus or minus one revolution per

minute.

All mixers shall be properly maintained in good working order in every respect.

For each mixer proposed, the contractor shall provide a copy of the manufacturer's

specification and statement of performance capability.

The amount of concrete mixed in any one batch shall not exceed the rated capacity of

the mixer.

The whole of the mixed batch shall be removed before materials for a fresh batch

enter the drum.

On cessation of work, including all stoppages exceeding 20 minutes, the mixers and

all handling plant shall be washed out with clean water.

Concrete mixed as above shall not be modified by the addition of water or otherwise

in order to facilitate handling or for any other purpose.

6.6.5 Concrete Production Records

The batch plant shall be equipped with an automatic recorder which shall, as a

minimum, record the following information: grade of concrete, date, time,

cumulative production for each grade of concrete for the day, truck number, cement

and aggregate scale tare, individual weights of cement, each aggregate, admixture,

water and the moisture compensator setting.




_________________________________________________________________________________


6.6.6 Separation of Constituent Materials

Separate bins or compartments shall be provided for each size of aggregate and type

of cement.

Coarse aggregates shall be separated into the following sizes and stored separately:

40-20 millimetres, 20-10 millimetres and 10-5 millimetres.

6.6.7 Interlock of Discharge Gates or Valves

Batcher discharge gates or valves shall be interlocked with the batcher charging gates

or valves such that the discharge gates or valves cannot be opened before the

charging gates or valves are fully closed.

Accurate automatic admixture dispensers shall be provided and interlocked into the

batching sequence. The location of the discharge of the admixture shall be in

accordance with the manufacturer's recommendation.

6.6.8 Sampling Facility and Batching Tolerance

The plant shall be arranged so as to facilitate the inspection of all operations at all

times. Provisions shall be available to obtain representative samples of the materials

as batched.

The batching scales shall be accurate when static load tested to plus and minus 0.4

percent of the total capacity of the scale.

6.6.9 Transporting Equipment

All concrete shall be transported in vehicles that comply with the requirements of

ASTM C 94, and the recommendations of ACI 304R, Chapter 5.

6.6.10 Mixing times

The cement and aggregates shall be thoroughly mixed dry. Mixing shall be

continued, after addition of water, for not less than two minutes and until concrete of

uniform colour and consistency is obtained.




_________________________________________________________________________________


6.7 Formwork

6.7.1 General

Formwork shall be designed and constructed in accordance with the requirements of

BS 5975 and shall ensure that the finished concrete members conform accurately to

the dimensions, lines and elevations shown on the drawings and to the specified

tolerances.

Top formwork shall be provided to slopes of 30 degrees or more from horizontal.

Contractor shall submit details of formwork to Owner for review and approval in

advance of concreting.

Formwork shall be of such strength and rigidity as to carry the weight and pressure

from the fresh concrete to be placed on or against it, together with all constructional,

wind or other load likely to be imparted to it, without producing deformation of the

finished concrete in excess of the specified tolerances.

All formwork shall be sufficiently tight without plugging to prevent loss of grout

during the vibration of the concrete.

The faces of formwork shall be clean, free from protrusions, adhering grout and other

imperfections or defects.

6.7.2 Form Ties

Form ties shall be factory fabricated, removable or snap-off metal ties which will

neither allow formwork deflection nor spall the concrete when removed. The ties

shall be provided with backing plates to distribute loads evenly to the formwork.

Bolt or tie systems which, when removed, leave a hole through the member, shall not

be permitted in liquid retaining structures. Ties shall be fitted with devices that will

leave holes in the concrete surface not less than 6 millimetres nor more than 25

millimetres in diameter. Bolts and rods that are to be completely withdrawn from the

finished concrete shall be coated with an approved non-staining bond breaker prior to

concreting.




_________________________________________________________________________________


6.7.3 Boxouts

Boxes for forming holes shall be constructed to be easily removable without

damaging the concrete during removal. They shall be properly vented to permit the

escape of entrapped air and shall be capable of being sealed subsequently to prevent

the loss of grout. The use of polystyrene blocks for forming holes shall not be

allowed unless used purely as a void filler within otherwise rigidly constructed

boxes.

6.7.4 Inspection Holes

Openings in formwork for inspection and cleaning-out shall be formed so that they

can be completely sealed before the placing of concrete.

6.7.5 Formwork Props

All props shall be supported on adequate sole plates and shall not bear directly on or

against previous concrete. They shall be capable of being released gently without

shock to the supported formwork. No appliance for supporting the formwork shall be

built into the permanent structure.

6.7.6 Chamfers

All outward projecting 90 degree corners shall have a 25 millimetre x 25 millimetre

chamfer unless shown otherwise on the drawings.

6.7.7 Formwork Removal

Formwork shall not be removed before the minimum allowable times given in Table

6.3 have elapsed after placing concrete.




_________________________________________________________________________________


TABLE 6.3

MINIMUM PERIOD BETWEEN PLACING CONCRETE

AND REMOVAL OF FORMWORK

Element Time (Days)

Beam sides, walls, columns 1½

Slabs (props left under) 4

Beam soffits (props left under) 7

Removal of props to slabs 10

Removal of props to beams 16

6.7.8 Treatment of Formwork

Forms, other than retained-in-place metal forms, shall be coated with form oil (mould

oil) or form release agent before the concrete is placed. The coatings shall be

approved commercial formulations of satisfactory and proven performance. They

shall not bond with, stain or adversely affect the concrete surfaces and shall not

impair subsequent treatment of concrete surfaces depending upon the bond or

adhesion, nor impede the wetting of surfaces to be cured with water or curing agent.

Forms for unexposed surfaces that are to be treated with a waterproof membrane

shall be moistened with water immediately before placing concrete. Surplus oil on

form surfaces, reinforcing steel and construction joints shall be removed before

placing the concrete.

Where a concrete surface is to be permanently exposed only one release agent shall

be used throughout the entire area. Release agents shall be applied evenly. Where

the concrete surface is to receive an applied finish, care shall be taken to ensure

compatibility between the release agent and the finish.




_________________________________________________________________________________


6.8 Reinforcement

6.8.1 Preparation

Reinforcement shall be wire brushed and cleaned to remove all loose millscale, rust,

grease and dust before it is placed in position.

Bending dimensions, cutting and scheduling shall be in accordance with BS 4466.

6.8.2 Site Fixing

Reinforcement shall be fabricated to the shapes and dimensions shown and shall be

fixed in strict accordance with the Drawings. Cutting and bending shall be in

accordance with BS 4466 and shall be done without the application of heat and in a

temperature no less than 5°C. Suitable precautions shall be taken by Contractor to

prevent displacement of the reinforcement during the placing and compaction of the

concrete. The placement of reinforcement with kinks or bends shall not be permitted.

6.8.3 Supports

Where required to support and retain the reinforcement in its correct position,

Contractor shall provide templates, stools or other supports.

Precast concrete support blocks for reinforcement shall be manufactured from Grade

30 concrete of 10 millimetre maximum aggregate size to ensure the correct cover

thickness. They shall be cured before use and carefully stored on the site to avoid

contamination. Plastic supports may be used subject to the approval of Owner.

Where precast concrete support blocks are used, they shall be wedge-shaped, not

larger than 90 millimetres by 90 millimetres, of a thickness necessary to provide the

required cover and with an embedded hooked stainless steel tie wire for anchorage.

If the formed surface is exposed to view, the precast concrete support block shall be

the same quality, texture and colour as the finished surface.




_________________________________________________________________________________


6.8.4 Cover and Laps

Cover to reinforcement shall be in accordance with the drawings. Cover shall be

maintained over ties, stirrups and lap splices. Except where shown otherwise the lap

length for high yield steel shall be in accordance with BS 8110. Laps and joints in

reinforcement shall be made only at the positions shown on the drawings or as agreed

by the Owner.

6.8.5 Tie Wire

All intersections of bars shall be tied with 16 gauge black annealed iron wire and

shall have the loose ends pointing away from the formwork, such that they do not

project into the specified concrete cover.

6.8.6 Welding

Welding of bar reinforcement at intersections or for the joining of bars shall not be

permitted.

6.8.7 Mesh Laps

Wire mesh fabric reinforcement shall not be continuous across joints. Lap splices

shall be at least one full mesh plus 50 millimetres, staggered to avoid continuous laps

in either direction, and securely wired.

6.9 Built-in Items, Holes and Cavities

Contractor shall be responsible for the co-ordination of all requirements as regards provision

of holes, chases, cavities and fixings.

Where reinforcing bars at the specified spacing would foul holes of size less than 250

millimetres x 250 millimetres the full length of the bar shall be moved to one side. Bars shall

be positioned to provide the specified cover to the face of the hole. In the case of holes

exceeding 250 millimetres x 250 millimetres the bars shall be cut on site and lapped with

additional equivalent bars, or placed as shown on the drawings.




_________________________________________________________________________________


Embedded items shall be fabricated and installed to satisfy design requirements. Where

pipes, sleeves, water bars or other items are built into concrete, they shall be rigidly secured

in position to prevent movement. Inserts for anchoring structural, architectural, electrical and

mechanical fixtures and fittings shall be cast in-situ with the concrete according to the

manufacturer's instructions and shall be free from external coatings which might reduce the

bond.

Where in-situ casting is not suitable or is constrained by the proximity of construction

equipment box-outs may be used. Contractor shall submit for approval of Owner on a case

by case basis his proposals for using box-outs.

Embedded items which are galvanised shall not be tied to or in contact with reinforcing steel.

Dissimilar metals shall not be in contact within the concrete. Concrete cover to embedded

items shall not be less than the cover to the reinforcement and the concrete shall be worked

around the items so as to achieve full compaction.

Bolts, hooks and other fixings shall be embedded in concrete, or holes shall be drilled and

fitted with threaded expanding anchors to receive the bolts. Contractor shall ensure that

bolts, hooks and other fixings are accurately positioned. Holding down bolts for machinery

shall be set to template.

Wherever possible, Contractor shall build in all pipework and metalwork which passes

through walls and floors, and he shall ensure that it is thoroughly encased in concrete.

6.10 Concreting

6.10.1 General

The finished concrete shall be dense and free from honeycombing. Any free water

shall be removed from locations where concrete is to be placed before placing the

concrete. Any flows of water shall be diverted away from the Works without

washing over freshly deposited concrete. All debris and foreign material shall be

removed from the interior of the formwork. Runways shall be provided for wheeled

concrete-handling equipment, such equipment shall not be wheeled over

reinforcement nor shall runways be supported on the reinforcement. Reinforcement,

embedded items and formwork shall be inspected and approved before the placing of




_________________________________________________________________________________


concrete. Wind blown contaminants (such as salt and dust) shall be removed from all

embedded items, reinforcement and formwork prior to the placing of concrete.

6.10.2 Transport

Transport of concrete from the mixer to the forms shall be in accordance with BS

5328: Part 3, Clause 4.10.

6.10.3 Chutes and Drop Pipes

Concrete may be placed directly from a truck mixer or other transporting equipment.

The chutes attached to this equipment may be used provided that the clear free fall

from the end of the chute is no greater than 1 metre and that the slope of the chute

does not exceed 1 vertical to 1 horizontal. When transferring concrete vertically

from higher to lower elevations, drop pipes (trunking) shall be used.

6.10.4 Buckets and Skips

Concrete buckets and skips may be used provided that the equipment is designed to

discharge concrete of the slump required, the discharge gates are tight against

escaping grout when closed and that any free fall of concrete does not exceed 1

metre.

6.10.5 Pumps

The delivery pipe shall be steel or heavy duty flexible hose and the concrete shall be

supplied continuously to the pump. The pump shall be of adequate capacity and

power to ensure delivery of a continuous supply of concrete. Whenever the supply of

concrete to the pump is interrupted for more than 1 hour the chutes, pumps, pipes and

any other means of distribution shall be thoroughly flushed out with water and

cleaned, and shall be flushed with water immediately prior to the resumption of

concreting. All wash water used shall be discharged outside the formwork and clear

of any freshly placed concrete. When pumping is complete, the concrete remaining

in the pipeline shall be ejected without contaminating the concrete in place. At all

times when pumping concrete Contractor shall provide adequate alternative

arrangements for placing the concrete in case of a breakdown of the pumping

equipment.




_________________________________________________________________________________


6.10.6 Placing and Compacting Concrete

Concrete shall be placed and compacted in accordance with the recommendations of

ACI 304R, Chapter 6 and ACI 309R.

No concrete shall be placed until Contractor has obtained the approval to do so from

Owner. Process control sheets shall be developed jointly between Contractor and

Owner to administer the procedures for inspection and approval.

Concrete shall be handled from mixer to forms in a continuous manner until the

approved pour has been completed and shall be deposited as close as possible to its

final position in the forms and in layers not exceeding 500 millimetres. The total

time taken from the addition of water to the mix until the completion of finishing

operations on any batch of concrete shall not exceed 2 hours and be within 30

minutes of the discharge from the agitator.

Temporary or permanent stoppages of work shall only be made against stop ends and

between specified or approved construction joints.

Each batch of concrete shall be consolidated by internal vibrators according to the

manufacturer's recommendations with respect to effective radius and time of

vibration. The vibrators shall be withdrawn immediately water or a thin film of

mortar begins to appear on the surface of the concrete. Vibrators shall be withdrawn

slowly from the concrete.

Vibrators shall be inserted vertically at uniform spacing to ensure that the effective

vibrated areas just overlap.

Vibrators shall not be used for moving concrete within the forms.

Slabs 100 millimetres thick or less shall be compacted by vibrating beams or other

approved techniques and not by internal vibrators.

Contractor shall ensure that for all concreting operations sufficient vibrators are

available to facilitate continuity of the placing and that stand-by vibrators are

available in the event of breakdowns. Concrete placing shall cease in the event of a




_________________________________________________________________________________


total breakdown of the vibration equipment and shall be reduced with partial failure

of the equipment. Concrete that has not been properly compacted shall be rejected.

Concrete which is transported in truck mixers or agitators, or concrete which is truck

mixed shall normally be placed within 90 minutes.

6.10.7 Hot Weather Concreting

When the temperature of fresh design mix concrete exceeds 30°C with the

consequence that workability is adversely affected, mixing and placing of the

concrete in question shall be terminated.

Special precautions shall be taken to ensure the concrete temperature at placing is

maintained below 30°C. These precautions may include:

• Protecting all aggregate stockpiles, water lines and tanks as well as the mixer

from the direct rays of the sun.

• Mixing water cooled by the addition of ice to the storage tanks.

• Concreting carried out during the cooler parts of the day or during the night.

• Cooling all chutes, formwork and reinforcement by watering when possible,

or otherwise protecting the site of placing from the direct rays of the sun.

Any water so used shall be removed before placing the concrete in the

formwork.

• Providing wind shields during periods of drying winds.

To minimise the possibility of plastic shrinkage of the fresh concrete the rate of

evaporation of water from the surface of the concrete shall be measured according to

ACI 305R and if this exceeds 1.0 kilogram per square metre per hour, the concrete

shall be protected immediately after placing.




_________________________________________________________________________________


6.10.8 Concreting in Cold Weather

Concreting at ambient temperatures below 2°C may be carried out only if the

following conditions are met:

• The aggregates and water used in the mix shall be free from snow, ice and

frost before placing concrete.

• The formwork, reinforcement and any surface with which the fresh concrete

will be in contact shall be free from snow, ice and frost and shall be at a

temperature above 0°C.

• The initial temperature of the concrete at the time of placing shall be at least

5°C.

• The temperature at the surface of the concrete shall be maintained at not less

than 5°C at any point, nor should water curing be applied until the concrete

reaches a strength of 5N/mm² as confirmed by tests on cubes matured under

similar conditions.

The Contractor shall take precautions to prevent the temperature of any concrete

falling to 0°C during the first five days after placing.

Concreting is not to be carried out when the air temperature is below 2°C on a falling

thermometer or 1°C on a rising thermometer.

6.10.9 Time Between Pours

The time between successive vertical lifts shall not be less than 3 days and not more

than 7 days. The time between placing concrete in adjacent pours separated by

construction joints shall not be less than 21 days.

6.10.10 Floor Slabs on Grade

Immediately before placing concrete, the capillary water barrier or subgrade under

slabs in buildings shall be covered with a vapour barrier unless membrane

waterproofing is indicated. Punctures and tears during subsequent operations shall




_________________________________________________________________________________


be patched. Edges shall be lapped not less than 100 millimetres and ends not less

than 150 millimetres. Patches and lapped joints shall be sealed with a pressure-

sensitive adhesive or pressure-sensitive tape, not less than 50 millimetre wide and

compatible with the membrane.

6.10.11 Construction Joints

Before commencing construction of any structure, Contractor shall submit for Owner

approval drawings showing full details of construction joints including their location

and lift heights. No construction joints shall be formed which are not shown on

approved drawings.

Construction joints shall be provided with water stops where shown on drawings,

where joints in concrete elements are in contact with ground soil, and wherever

construction joints occur in liquid retaining structures. Water stops shall be properly

installed and joined to other water stops at the ends of the joints to provide a

continuous barrier to the passage of water in the finished structure.

To ensure control in the placing of concrete slabs Contractor shall provide control

boards to form panels not larger than 15 square metres in plan area. These shall be

lifted as concreting proceeds. Where ready-mixed concrete is used, the control

boards shall be positioned so as to enclose a volume of concrete equal to that

delivered by each truck.

Horizontal construction joints in walls shall be formed along straight lines coinciding

with the full height of the formwork. Construction joints shall be formed normal to

the surface of the retained concrete.

As soon as possible after concreting, and while the surface is still green, the surface

of the concrete forming the joint shall be freed of loose aggregate and sprayed with a

fine spray of water to prevent the formation of laitance. Where laitance has not been

removed before the concrete has hardened it shall be removed by use of an approved

power operated hammer. Subsequently all excess water shall be removed by a jet of

compressed air and the surface left clean to receive further concrete.




_________________________________________________________________________________


6.10.12 Water stops

Water stops shall be an approved polyvinyl chloride (PVC) or rubber proprietary

brand conforming to U.S. Corps of Engineers CRD-C572 or CRD-C513. The

minimum web thickness shall be 4.5 and 10 millimetres for PVC and rubber water

stops respectively. Site jointing and all fixing shall be strictly in accordance with the

manufacturer's recommendations. All cruciform and T-joints shall be standard

manufactured items.

6.10.13 Joint Sealant

Joint sealant shall conform with the requirements of ASTM C 920 and ASTM D

1190 elastomeric joint sealant. The concrete surfaces adjacent to the joint sealant

shall be clean, dry and free from oil or other foreign matter and shall be prepared in

accordance with the manufacturer's instructions. The sealant shall completely fill the

rebates designated for it and shall be fully bonded to the concrete along both sides of

the joint. It shall be debonded from the back face of the joint by means of an

approved bond breaker.

6.10.14 Joint Filler

Joint filler shall be of an approved proprietary brand conforming to ASTM D 1751 or

ASTM D 1752 and shall be installed according to the manufacturer's instructions.

The joints shall be filled with one thickness of the material to the dimensions shown

on the drawings.

6.10.15 Bond Breaker

Bond breaking material shall be compatible for use with the approved joint sealant

and joint filler and shall be applied at the interface between sealant and filler as

shown on the drawings. The bond breaker shall completely span the interface

between filler and sealant.




_________________________________________________________________________________


6.10.16 Floor Screeds

Floor screeds shall be constructed to the lines, elevations and crossfalls shown on the

drawings and shall consist of Grade 20 concrete with 10 millimetre maximum size

aggregate.

6.10.17 Concrete Benching

Concrete for benching in manholes and structures shall consist of Grade 20 concrete

with 20 millimetre maximum size aggregate. It shall be placed with low workability

to the shape required and, while still green, shall be finished with not less than 50

millimetres of Grade 20 concrete with 10 millimetre maximum size aggregate to a

steel trowelled finish and to the contours shown on the drawings.

6.10.18 Concreting on "no-fines" Concrete

The exposed surfaces of no-fines concrete upon which, or against which, further

concrete is to be placed shall be completely covered with an approved breather type

membrane complying with the requirements of BS 4016. Care shall be taken to

ensure that the paper is not cut or torn during the erection of formwork or the fixing

of reinforcement. The laps of adjacent sheets of building paper shall not be less than

200 millimetres. In the event of cuts or tears in the paper, patches with a minimum

overlap of 200 millimetres shall be used to cover the damaged area and care taken

during concreting to ensure that none of the grout from the concrete being placed

escapes into the no-fines concrete.

6.11 Curing and Protection Of Concrete

6.11.1 General

Concrete shall be cured for a minimum period of 7 days in accordance with the

requirements of ACI 308.

Immediately after placing, the concrete shall be protected from premature drying,

mechanical injury and from the effects of rain or flowing water. All materials and

equipment needed for curing and protection shall be available at the point of concrete




_________________________________________________________________________________


placing prior to the concreting operations. Concreting shall not proceed without this

provision.

No fire or excessive heat shall be permitted near or in direct contact with the concrete

or formwork at any time during the curing process.

6.11.2 Moist Curing

Concrete surfaces shall be maintained continuously wet for the entire curing period.

If the water stains or discolours the concrete surfaces which are to be permanently

exposed, the concrete surfaces shall be cleaned. If the forms are removed before the

end of the curing period, curing shall be carried out as on unformed surfaces, using

suitable approved materials.

6.11.3 Curing Compound

Curing compound shall only be used with the approval of Owner.

The curing compound shall conform to ASTM C 309R, Type 1 - D Class A or B.

Curing compound shall not be used on surfaces that are to receive any subsequent

treatment which is dependent upon adhesion or bonding to the concrete. Styrene

acrylate or chlorinated rubber compound meeting Class B requirements may be used

for surfaces which are to be painted. Curing compound shall be applied to formed

surfaces immediately after the forms are removed and prior to any patching or

surface treatment except the cleaning of loose sand, mortar, and debris from the

surface.

For slabs the curing compound shall be applied to slab surfaces as soon as the

finishing operations are complete.

The compound shall be applied in a one-coat continuous operation by mechanical

spraying equipment, at a uniform coverage in accordance with the manufacturer's

instructions. Two coats may be required due to wind conditions or surface texture

and shall only be applied with the approval of Owner. Concrete surfaces which have

been subjected to rainfall within 3 hours after curing compound has been applied

shall be resprayed at the coverage specified for the initial application.




_________________________________________________________________________________


Surfaces permanently exposed to view shall be shaded from direct rays of the sun for

the duration of the curing period. Surfaces coated with curing compound shall be

kept free from pedestrian and vehicular traffic, and from other sources of abrasion

and contamination during the curing period.

6.11.4 Impermeable Sheeting

Exposed concrete surfaces shall be covered with impermeable sheeting, properly

secured to prevent removal by wind and the development of air spaces beneath it.

Joints in the sheeting shall be lapped by at least 300 millimetres.

6.11.5 Limitation of Temperature Differentials

The temperature differentials in concrete elements greater than 0.5 metre thick shall

be limited to a maximum permissible between the core and the surface of 20°C.

6.12 Surface Treatment and Remedial Works

6.12.1 General Requirements

All exposed faces of concrete shall be hard, dense, smooth and free from

honeycombing, air and water holes and other blemishes.

6.12.2 Surface Defects

Within 24 hours of the removal of the formwork surface defects shall be remedied as

follows:

• For permanently exposed surfaces, fins shall be removed by rubbing down

and all grit and dust therefrom thoroughly washed off with clean water.

Holes left by the removal of tie rods shall be reamed and filled with an

approved proprietary brand non-shrink mortar.

• For all surfaces, honeycomb and other defects shall be cut back to sound

concrete and to a depth of not less than 25 millimetres. The edges of the

repair area shall be cut perpendicular to the surface of the concrete and the

area of repair cleared of all loose material. The prepared area shall be




_________________________________________________________________________________


thoroughly dampened and the repair shall be completed using an approved

proprietary brand non-shrink cementitious repair mortar thoroughly tamped

into place. In lieu of patching, a small shotcrete gun may be used. The

patches shall be finished flush with adjacent surfaces. The air temperature

shall be above 15 degrees centigrade while making the repair and during the

following 72 hours curing period.

6.12.3 Treatment other than for Surface Defects

Defective areas which, in the opinion of Owner, cannot be remedied by the treatment

specified above shall be cut back until sound concrete is encountered. The limits of

the cut back area shall be directed by Owner.

The sides of the cavity created and any reinforcement shall be cleared of all loose

material, oil, grease and other deleterious material. Formwork shall be erected to

restore the affected surface to the lines and level required and the cavity filled with

concrete of the grade required in the final Works. Before filling with new concrete

the existing concrete surfaces of the cavity shall be dampened with water. Any

excess water shall be removed before concreting.

Care shall be taken to ensure that the correct cover to reinforcement is achieved, that

the finished surface is flush with the surrounding surfaces and that the replacement

concrete is properly compacted.

6.12.4 Replacement of Concrete

As and when directed by Owner, Contractor shall cut out and replace concrete for

any of the following reasons:

• The concrete does not conform to the Specification.

• Deleterious materials or materials which are likely to produce harmful

effects have been included in the concrete.

• Honeycombed or damaged areas occur.

• The finished concrete sizes are not in accordance with the drawings within

the tolerances specified.

• The setting-out is incorrect.

• The steel cover has not been maintained.




_________________________________________________________________________________


• The protection, including curing, of the concrete during construction was

inadequate, resulting in damage.

• The work of making good or other remedial measures have not been carried

out to Owner satisfaction.

• Deformation of or damage to the Works has taken place due to inadequate

formwork or to premature or excessive loading.

6.13 Concrete Finishes

6.13.1 Formed Finish - F1

This shall be the standard of finish to all concrete formed surfaces that are to be

concealed in the completed work or by other construction, unless otherwise indicated

or specified.

The surface treatment shall comprise the filling of any depressions greater than 12

millimetres deep, including tie-rod holes, and the removal of any fins exceeding 6

millimetres in height by rubbing down with carborundum stone.

The surface so formed shall be within plus or minus 12 millimetres of the required

line and level. Abrupt irregularities shall not exceed 6 millimetres and gradual

surface irregularities shall not exceed plus or minus 6 millimetres when measured

with a 1.5 metre straight edge.


F2 form finishes shall generally comprise all concrete surfaces that are exposed

either to air or water or that are to be covered with a coating material applied directly

to the concrete, or a covering material bonded to the concrete such as waterproofing,

and are not included in the classification for F3 finishes. The surfaces shall be

formed using close fitting good quality plywood or steel faced boarding with true

arises without visible offsets or bulges. Any fins greater than 6 millimetres in height

shall be rubbed down with carborundum stone. The surfaces so formed shall be

within plus or minus 3 millimetres of the required line and level. Abrupt

irregularities shall not exceed 6 millimetres and gradual irregularities shall not

exceed plus or minus 3 millimetres when measured with a 1.5 metre straight edge.




_________________________________________________________________________________



F3 form finishes shall generally comprise those surfaces which convey water or

against which water is impacted.

The formed surfaces shall comply with the requirements for F2 finishes with the

exception that abrupt irregularities and fins shall be no more than 3 millimetres in

height.

In the event that the formed surfaces require treatment following the removal of

formwork, all fins over 3 millimetres in height shall be rubbed down with

carborundum stone and the formed surfaces treated with a filling paste comprising

one part ordinary Portland cement and two parts well graded sand passing a Nr. 30

sieve, with water added to give the consistency of thick paint. After the surface has

been thoroughly wetted and allowed to approach surface dryness, the mortar shall be

vigorously applied to the area by clean burlap pads or by cork or wood-floating, to

completely fill all surface voids. Excess grout shall be scraped off with a trowel. As

soon as it can be accomplished without pulling the mortar from the voids, the area

shall be rubbed down with burlap pads having on their surface the same sand-cement

mix specified above but without any mixing water, until all of the visible grout film

is removed. The finish of any area shall be completed in the same day, and the limits

of a finished area shall be made at natural breaks in the surface. The surface shall be

continuously moist cured for 48 hours.

6.13.4 Rough Slab Finish - U1

Immediately after consolidation, slabs shall be screeded with straight edges to bring

the surface to the required finish level with no coarse aggregate visible. The

resulting rough slab finish should be suitable to receive fill and mortar setting beds

for tile, terrazzo and other bonded applied cementituous floor finishes.

6.13.5 Wood Float Finish - U2

Wood float finish shall be applied to monolithic slab surfaces that are to receive

trowel and other finishes and slab surfaces which are to be covered with bituminous

waterproofing or elastomeric membrane roofing.




_________________________________________________________________________________


Wood float finishes shall be formed by smooth floating the accurately levelled and

screeded surface. Care shall be taken to ensure that the concrete is worked no more

than is necessary to produce a uniform surface free from screed marks.

6.13.6 Steel Trowel Finish - U3

Trowel finish shall be applied to monolithic slab surfaces that are to be exposed to

view and slab surfaces that are to be covered with resilient flooring, paint, or other

thin-film finish coating systems.

Immediately following the wood floating, the surface shall be steel-trowelled to

produce a smooth, dense surface free from blemishes including trowel marks. In lieu

of hand finishing, an Owner approved power finishing machine may be used in

accordance with the directions of the machine manufacturer. A final hard steel

trowelling shall be done by hand.

6.13.7 Non-Slip Finish - U4

Brush finish shall be given to exterior concrete platforms, steps and ramps. After

wood floating, the surface shall be lightly steel-trowelled, and then brushed with a

fibre-bristle broom.

6.14 Corrosion Protection of Concrete

6.14.1 General

Corrosion protection of buried concrete structures shall be in accordance with the

"Standard Specification for the Corrosion Protection of Buried Concrete Structures".

External surfaces of reinforced concrete structures and pre-cast concrete units buried

or in contact with the ground, shall be protected by plastic membrane.

Alternatively, concrete surfaces of small structures in contact with the ground shall

be coated with a cold applied liquid coating.

Mass concrete used for structural purposes may or may not be tanked depending on

the degree of exposure to sulphate attack (see Section 6.1.2).




_________________________________________________________________________________


Mass concrete used for fill or other non-structural purposes does not require tanking.

The blinding course beneath reinforced concrete shall be overlain with a water and

vapour proof polyethylene membrane. A cold applied adhesive plastic membrane

shall overlap the foundation membrane to form an effective seal. The membrane

shall fully encase the underground structure before backfilling. The tanking system

used shall be suitable for effective protection against aggressive salts in a hot, wet

environment and shall be tested, installed, formed and completed in accordance with

the manufacturer's instructions. Chamfers or fillets shall be formed to ensure

continuity of membranes that cover right angle concrete joints. To ensure the

tanking system is not damaged when erecting formwork and reinforcement

Contractor shall use a sandwich foundation sealing system incorporating the

impervious barrier between two layers of blinding concrete. To ensure that the

tanking system is not damaged during backfilling Contractor shall use a protective

covering as described in Section 6.14.6.

6.14.2 Materials

Plastic membranes for tanking shall be of a proprietary brand especially designed and

manufactured for the purpose of tanking, and shall comprise a chemically inert

backing sheet with a bituminous adhesive on one side, with a minimum combined

thickness of 1.5 millimetres. The width of roll shall not be less than one metre.

Plastic membranes below structural bases shall be of two types:

• Polyethylene sheeting with a minimum thickness of 1.0 millimetres.

• Textured high density polyethylene membrane with a minimum thickness of

1.5 millimetres and minimum friction angle of 31o between the membrane

and both the underlying blinding concrete and the overlying structural

concrete.

Textured high density polyethylene membrane shall be used where the structure is

designed to resist horizontal forces unless otherwise shown on drawings.




_________________________________________________________________________________


The cold applied liquid coating shall be as detailed in "Standard Specification for the

Corrosion Protection of Buried Concrete Structures" and "Standard Specification for

Coatings and Linings".

Storage of all materials shall be in accordance with manufacturer's recommendations.

6.14.3 Surfaces to be Protected

All surfaces to be tanked shall have a smooth finish, free of sharp projections or

hollows. Cured concrete bases and pre-cast concrete units shall be dry and swept

free of sand, dust and stones.

6.14.4 Priming

Prior to application of tanking, the concrete shall be primed with a compatible primer

recommended and obtained from the manufacturer of the plastic membrane.

The area to be primed at any one time shall not exceed that which can have the

tanking applied before the primed area becomes contaminated with wind-blown sand

and dust.

6.14.5 Application of Tanking

The membrane shall be applied with the adhesive face over the dry primed surface.

Adjacent rolls of the membrane shall overlap by a minimum of 50 millimetres, and

end-to-end joints shall overlap by at least 100 millimetres.

All overlaps and joints shall be firmly pressed or rolled to ensure that the joint is

water tight.

On all internal or external corners or angles, a 300 millimetres wide reinforcing strip

of the same tanking material shall be applied. On internal angles the reinforcing strip

shall be applied over a fillet of primed mortar or sealing compound.




_________________________________________________________________________________


6.14.6 Protective Covering for Tanking Membrane

The protective covering shall be a tough, hard, impact resistant bituminous board

containing stone dust filling and chippings and shall have at least one smooth face. It

shall be a minimum of 3 millimetre thick, rot-proof, water repellent and resistant, and

impervious to groundwater chemical attack. It shall also be proof against attack from

insects, rodents and termites and shall not be capable of supporting or hosting

vegetable or microbial growth. It shall be supplied in sheets no larger than 2 metres

by 3 metres.

The protective covering shall generally be held against the structure by the weight of

the soil behind. If any fixing to the structure is required, it shall be accomplished

without any damage to the waterproof tanking material. Contractor shall seal the

joints between boards with a strong adhesive tape.

6.15 Precast Concrete Flags, Kerbs, etc.

Precast concrete units shall be obtained from an approved manufacturer or cast at the Site of

the Works in accordance with the requirements of BS 7263. They shall be true to dimension

and shape, with true arises and with smooth exposed faces free from surface blemishes, air

holes, crazing and other defects, whether developed before or after building-in. Units shall be

tested for water absorption in accordance with BS 7263 and shall display no greater

absorption than that specified under Clause 13 of BS 7263: Part 1.

6.16 Setting Base Plates And Bearing Plates

6.16.1 General

After being set up and checked for alignment, level and verticality, base plates and

bearing plates shall be set with a proprietary non-shrink grout or mortar in

accordance with manufacturer's recommendations.

The plates shall be set and anchored to the correct alignment and elevation using

metal wedges, shims and/or setting nuts. Concrete and metal surfaces in contact with

the bedding shall be clean and free from oil and grease. Concrete surfaces shall be

free from laitance and shall be dampened.




_________________________________________________________________________________


6.16.2 Non-shrink Grout

Non-shrink grout shall comply with the requirements of CRD-C621 with a minimum

28 day compressive strength of 35 N/mm².

Mixing and placing shall conform with the manufacturer's recommendations. Forms

shall be used to retain the grout and the surface finish attained shall conform with

that of the structural surfaces surrounding it. The grout shall be placed quickly and

continuously completely filling the void without segregation or bleeding.

6.16.3 Slip Bearings

Slip bearings shall comprise two (2) layers of approved proprietary, preformed

bearing strips of dense extruded polyethylene sheet each 1.5 mm thick. Material

minimum safe load capacity shall be 0.1 N/mm². The maximum coefficient of

friction shall be 0.28.

The concrete surface shall be prepared, and the bearing material bonded to the

concrete surface in accordance with the manufacturer's recommendations.

7.0 DOCUMENTATION TO BE SUBMITTED

Contractor shall submit the following documentation to Owner for review and approval:-

7.1 Reports

Materials management reports for quality control of all aggregate and concrete testing

activities.

Quality control documentation reports for daily concreting records.

7.2 Technical Data

Test certificates for cement and reinforcing steel.

Manufacturer's technical data sheets for all proprietary products.




_________________________________________________________________________________


Quality control documentation and calculations for concrete mix design details.

Loading and calculations relating to design of formwork.

General arrangement drawings of construction joints and identifying sequence of

construction.

brna-sp-cs-012-03 - concrete

Documents