Civil specification.pdf

7/22/2019 Civil specification.pdf

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PROPOSED COMMERCIAL/RESIDENTIAL BUILDING AT FANJA WEST

GENERAL SPECIFICATION

SECTION INDEX (See end of Specification for Detailed Index)

1. General Requirements 02 - 05

2. Demolitions and Alterations 06 - 07

3. Excavation and Earthwork 08 - 17

4. Concrete Work 18 - 56

5. Block work 57 - 63

6. Protection of Substructure 64 - 70

7. Roofing 71 - 78

8. Wood Work / Carpentry and Joinery 79 - 191

9. Structural Steelwork and Metalwork 192 - 198

10. Floor Wall and Ceiling Finishings 199 - 205

11. Glazing 206 - 208

12. Painting and Decorating 209 - 215

13. Specialist Painting & Decorating & Gold Plating 216 - 223

14. Marble & Granite Works 224 - 228

15. External Works 229 - 237

16. Building Services - General 238 - 256

17. Air Conditioning and Ventilation 257 - 272

18. Piped Services 273 - 306

19. Thermal and Acoustic Insulation 307 - 31220. Electrical Services 313 - 315

21. H.V.Distribution and Sub-Station 316 - 329

22. L.V.Distribution 330 - 351

23. Lighting Distribution and Fittings 352 - 364

24. Telephone System 365 - 367

25. Fire Alarm System 368 - 371

26. TV Central Antenna and Sound System 372 - 373

27. Call Bell System 374

28. Lightning Protection System 375

29. Detailed Index 376 - 403


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GENERAL SPECIFICATION AL ILHAM ENGINEERING CONSULTANTS

1.0 GENERAL REQUIREMENTS

1.1.1 Specifications & Drawings

a) This Specification shall be read in conjunction with the drawings andStandard Contract Document and they should be taken as mutually

explanatory of one another.

b) Where detail drawings are provided these should be taken in preference tosmall scale drawings. Where further information is required theContractor shall refer this to the Engineer.

c) This Specification should be read in conjunction with the Bills ofQuantities where attached which may refer to special items not covered bythis Specification and any other matters pertaining to the specific project.

d) Where there is a variance between the Specification and the drawings,

such differences shall be referred to the Engineer who shall issueinstructions thereon as set out in Clause 5 (2) of the Conditions ofContract.

e) The importance of reading this Specification in its entirety is emphasized.Some items/operations are included in the Specification, but may not havebeen shown on drawings. No claim will be entertained for lack ofknowledge or non-awareness of items contained within this document.

1.1.2 Abbreviations

a) The following abbreviations used within these contract documents are

defined as follows:

BSS British Standard Specification.CP British Standard Code of Practice.ASTM American Standard for Testing Materials.CIF Cost Insurance and Freight.IEE Institution of Electrical Engineers.CIBSE Chartered Institution of Building Services

Engineers.DOE Directorate of Electricity.

1.1.3 Standard of Workmanship & Materials

a) All work shall be executed with the best Workmanship and to standardpractice. Relevant BS's and CP's shall be followed unless otherwise indicatedin accompanying drawings/Specifications or where otherwise directed by theEngineer.

b) Reference to BS which shall refer to the edition current at the time, shall notpreclude the use of materials from sources where other standards apply, but no


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materials to be incorporated in the works shall be in any respect inferior tothose which specifically comply with the BS.

c) Should the Engineer discover on the works any materials other than thoseapproved, he may order their removal from the site, including the demolitionof any works already built with these materials.

1.1.4 Proprietary Materials

a) All proprietary materials incorporated in the Works shall be fixed orapplied strictly in accordance with the Manufacturer's instructions.

b) Where proprietary materials are referred to in this Specification theintention is to establish the type and quality of materials required. Similarmaterials of equal and alternative manufacture may be offered insubstitution for prior approval of the Engineer.

1.1.5 Local Materials

All naturally occurring local materials used in the Works shall be from sourcesapproved by the Government of Sultanate of Oman.

1.1.6 Storage of Materials

All materials to be used in the permanent works shall be stored on racks orsupports, in bins, under cover, etc., as appropriate to prevent deterioration ordamage from any cause whatsoever, Storage arrangements for specific materialsshall be as approved by the Engineer.

1.1.7 Materials Generally

Where materials, products and workmanship are not fully specified they shall besuitable for the purpose of the works stated in or reasonably to be inferred fromthe Contract Documents, and in accordance with good building practice, to thesatisfaction of the Engineer.

1.1.8 Approval of Materials and Samples

a) Where approval of products or materials is specified, the Contractor shallsubmit samples or other evidence of suitability. The Contractor shall not

confirm orders or use materials until approval has been obtained.

b) Approved samples shall be retained on site for comparison with productsand materials used in the works and shall only be removed when no longerrequired.

c) Where samples of finished work are specified, the Contractor shall obtainapproval of stated characteristic(s) before proceeding with the Works andshall retain approved samples on site for comparison with the works.


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Samples, which are not part of the finished works, shall be removed whenno longer required.

d) Submission of samples shall be made at such times as to allow sufficienttime for approval to be given and on no account will delays to the work beaccepted where caused by failure in obtaining approval by the Engineer.

1.1.9 Single Source

Where a choice of manufacturer or source of supply is allowed for any particularproduct or material, the whole quantity required to complete the work must be ofthe same type, manufacturer and/or source. Do not change without approval.

1.1.10 Inspection and Testing

a) Whenever considered desirable Inspectors may be sent to the source ofsupply or Manufacturer's works to test the materials or supervise their

production. Materials shall be tested before leaving the supplier'spremises or Manufacturer's works as well as after delivery to the works.

b) Should it be decided not to send an Inspector to the source of supply orManufacturer's works, the Contractor shall obtain from the Supplier orManufacturer, Certificates of Tests etc., showing that the materials havebeen tested in accordance with the requirements of this Specification butneither the omission to send an Inspector nor the production ofCertificates of Tests as aforesaid, shall effect the power of the Engineer toreject after delivery materials found not to be suitable or not in accordancewith the Specification.

c) The Contractor shall allow reasonable time for the Engineer to makearrangements for inspection and give permission for despatch to the site.Delay to the Works arising from late notification of such details will notbe accepted as reason for delay in completion of the works.

1.1.11 Test Certificates

All Manufacturer's certificates of test, proof sheets, mill sheets, etc., (in theEnglish Language) showing that the materials have been tested in accordancewith the requirements of the appropriate BS, other relevant standard or thisSpecification, shall be supplied free of charge, if required by the Engineer.

1.1.12 Name of Manufacturers and Copies of Orders

Before ordering materials of any description for the permanent Works, theContractor shall if required by the Engineer submit to him for approval the namesand addresses of the Manufacturers and Suppliers proposed and source ofmaterial, and shall afterwards provide copy of the orders given by the Contractorfor the materials, if and when asked for.


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1.1.13 Spare Parts and As Built Drawings

a) The Contractor shall submit a comprehensive list of all proprietary articlesand materials used in the works containing catalogue reference numbers,colour shades etc., and the manufacturers and or suppliers' names,addresses, and where appropriate, local agents names and addresses

including a price list CIF to the site of works. This list shall be completein all respects and shall be submitted together with the "As-built"drawings and operation and maintenance manuals.

b) The number of As-built drawings shall be as follows:

i) One set on CD Rom.

ii) One set on 3.25 HD diskette (Compression may be used to achievea fit).

iii) Four sets of prints. Each set of drawings shall be properly boundand presented in a suitable manner acceptable to the Engineer.

iv) One set of negatives.

c) The Contractor shall provide FIVE copies of the Operation andMaintenance Manual and shall hand them over to the Engineer oncompletion of the work and before the issue of the Completion Certificate.

d) Failure to submit the above list and the "As-built" drawings will delayissue of the 'Completion Certificate'.

1.1.14 Fire Protection

a) Building materials used for fire protection shall have been tested to one ormore of the parts of BS 476 and shall have achieved an appropriate ratingfor the purpose for which they are to be used.

b) Fire protection boards shall be shall not support combustion or generate

toxic fumes when exposed to heat.

c) Handling, cutting, drilling and fixing shall be strictly in accordance withmanufacturer's instructions and as shown on Engineer's drawings.

d) Where possible each floor of a building shall be compartmented into zonesto limit the spread of fire or smoke. Each floor, plant rooms andkitchens/serveries shall always be separated.

e) Fire stopping shall be carried out using proprietary systems approved bythe Fire Officer and applied in accordance with the manufacturer'sinstructions.


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2.1.5 Making Good

a) When cutting new or enlarging existing openings work shall include forbuilding up jambs solid in block work in cement mortar, properly toothed

and bonded to old, for making good all work disturbed.

b) When building up existing openings work shall include for block work incement mortar, the full thickness of the wall properly toothed and bondedto existing work, and the making good of all finished surfaces.

c) Unless otherwise described, materials and workmanship are to complywith the Specifications of the following sections, which will be deemed tohave been read in conjunction with this section.

2.1.6 Services

Locate and mark the positions of services affected by the work. Arrange with theappropriate Authorities for the location and marking of the positions of mainsservices.

End of SectionEnd of SectionEnd of SectionEnd of Section


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3.0 EXCAVATION AND EARTHWORK

3.1 General

3.1.1 Nature of the Ground

The Contractor shall judge for himself the nature of the ground and shall be fullyresponsible for ascertaining all necessary information concerning permanentwater table, periods of rainfall, flooding of the site and all matters affecting theexcavations and foundation work.

3.2 Material

3.2.1 Backfill Material

Foundation trenches, column bases and the like shall be backfilled with selectedexcavated materials as described for imported fill, if approved by the Engineer.

3.2.2 Imported Fill

Material for backfill shall be selected graded granular fill free from clayand deleterious matter. The material shall be of high shear strength andbe unaffected by changes in moisture content. Excavated material mayonly be used after obtaining the engineers approval.

The properties of the material shall be in accordance with the limits

mentioned below, when tested in accordance with BS 1377: 1990.

The extent and the depth of fill shall be shown in the drawings or asdirected by the Contract Administrator. The fill shall be compacted inlayers not exceeding twice the average size of larger fragments. Thedegree of compaction achieved shall be verified on site by appropriatetesting as detailed in the specifications.

In general fill materials should have the following chemical composition:

Element % by Mass

Total Soluble Salts 2% maxTotal Chloride and Soluble Sulphate 1.5% maxTotal Soluble Sulphate SO3 0.17% maxTotal Chloride 0.05% maxOrganic matter 4% max


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3.2.2.1Types of Fill

(a) Fill Type A

Location to be used Under foundations

Type of soil Inorganic and free draining with no morethan trace amounts of organic matter,gypsum or other salts

Particle size 50mm max, 0-50% (by mass) passes 5mmsieve, 0-10% (by mass) passes 0.06mmsieve

Fines content 15% max

Gradation Well gradedLiquid Limit 25 max

Size of eachcompacted layer

150mm max

Compaction (1% ofDry Density asdetermined byModified ProctorTest)

97%

Frequency of Test One test per 300-400m2per layer

(b) Fill Type B

Location to be used Roadways, Sub-grade for ground bearingslabs and pavings, embankments, and areasto be used by construction or plantoperation

Type of soil Inorganic and free draining with no morethan trace amounts of organic matter,gypsum or other salts

Particle size 75mm max, 0-65% (by mass) passes 5mm

sieve, 0-20% (by mass) passes 0.06mmsieve


Gradation Well graded

Liquid Limit 40 max


250mm max

Compaction (1% ofDry Density as 95%


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determined byModified ProctorTest)


(c) Fill Type C

Location to be used Locations where installations of structureor equipment is not planned and in openareas where only grading is required.

Type of soil Inorganic granular, or silty, soil with a lowto negligible gypsum/salt content.

Particle size 100mm max


Gradation Well graded

Liquid Limit 50 max


500 max

Compaction (1% ofDry Density asdetermined byModified ProctorTest)

80%


3.2.3 Hardcore

Hardcore shall consist of naturally occurring gravel stones or otherapproved material, capable of being compacted to the specifiedrequirements.

It shall not contain particles exceeding 50 mm and not more than 5%shall pass through a 20mm sieve.

Total soluble salts max. 2%Total sulphates as SO3 max. 0.17Total chlorides C1- 0.05%Organic matter max. 4%

3.2.4 Stone Pitching / Mortared Rip Rap

The composition of the Stone Pitching shall be naturally occurring gravel stonesblinded with concrete and, wherever necessary, set over PCC. There shall becontinuous protection at the top and bottom of the slope with similar material andwith sizes as shown below.

If the overall stability of the slope is in doubt then this should be reported to theengineer.


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Stones shall be laid in a homogenous manner without voids and with sufficientconcrete to ensure proper cohesion and adhesion of all the constituents. Thesurface shall be straight without protrusions or pockets. The receiving slope shallbe dressed adequately, straightened, then thoroughly watered and compacted.Work should commence from top to bottom evenly at all sides.

The following thickness shall be adopted (for a maximum slope height of 4m):

Maximum Slope(Vertical: Horizontal)

Stone PitchingThickness (mm)

PCCThickness

(mm)

Protection at Top &Bottom of Slop

1:1.5 (Normal) 150 N/A 300x300

1:1.5 (WadiEmbankment)

200-300 50 300x300 Top, 600x600with Dry Rip Rap Bottom

1:1 150 50 300x300

1:>1 Obtain Engineers Advice

The size of the stones shall not exceed 100mm and not more than 10% shall passthrough a 20mm sieve. The stones shall be set in concrete grade 20N/mm2withnominal aggregate size of 10mm. PCC, wherever used, shall be grade 15N/mm2.

Expansion Joints to be 20mm with Joint Filler and 20x20mm hot poured Jointsealant, provided at approximately every 6m c/c throughout the entire width of

the slope from top to bottom.

In cases where protection against active water pressure should be considered,Weepholes are to be provided. These shall be in the form of 20mm PVC pipeseach having a 300x300x300mm stones inlet chamber wrapped with a non-degrading Geotextile. The spacing of the Weepholes shall be 1.5-2.0m Verticaland 3-4m Horizontal.

3.2.5 Crusher Dust Fines

Crusher dust fines shall be finely graded crushed stone to pass a 5mm mesh sieveand shall be free from deleterious matter, clay, silt, earth and organic matter.

3.2.6 Anti Termite Treatment

a) Anti Termite Treatment shall be carried out by a specialist sub-contractoras approved and a guarantee of 10 years for material and workmanshipshall be provided.

b) 1% emulsion strength of Fenvalerate, Permethrin or Chlordane equivalentchemicals as approved by the (a) Council for Conservation of


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Environment & Prevention of Pollution (b) Pesticides RegulationCommittee, Ministry of Agriculture and Fisheries (c) Ministry ofEnvironment and (d) Director of Environmental Health, Ministry ofHealth. The termicide chemical should show 100% efficacy for aminimum period of 10 years when tested in environment akin to Sultanateof Oman.

c) The rate of application of the chemical and various stages of applicationshall be as per the supplier's Specification and as approved by theEngineer.

3.3 Workmanship

3.3.1 Earthworks Method

The Contractor shall not undertake any earthworks, including the operation of anyborrow area or quarry, without having obtained the Engineer's prior approval tothe methods which he proposes to employ. He shall not thereafter modify such

methods without the Engineer's consent.

3.3.2 Correct Widths and Depths of Excavations

In the event of excavations being made larger than the sizes directed by theEngineer or as shown on the drawings, the Contractor shall fill in the excavatedvoid to the correct profile with plain concrete grade 1:3:6 as described under"Concrete Work" hereinafter or with approved selected fill compacted to a drydensity not less than 97% of its maximum dry density as determined in the tests toBS 1377:1990, as directed by the Engineer at the Contractor's own cost.

3.3.3 Method of Excavation

a) Excavation may be carried out by machine or any other method approvedby the Engineer. In soil, excavations shall be taken to within 150mm ofthe formation or foundation level and all subsequent excavation in anysection must be carried out by hand not more than 24 hours before thecommencement of construction in that section unless agreed otherwise bythe Engineer.

b) As soon as possible after inspection by the Engineer the bottom level ofthe excavation shall be sealed with blinding if specified and the requiredconstruction shall commence. No concrete shall be placed prior to the

Engineer approving the excavation.

3.3.4 Shoring Excavations

a) The Contractor shall, to the satisfaction of the Engineer, shore the sides ofexcavations for structures, trenches, and pits to prevent them fromslipping or falling. Should any slips, falls or settlement nevertheless occurthey shall be made good by the Contractor at his own expense withselected fill or with mass concrete as may be directed by the Engineer.


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b) In removing shoring from the sides of excavations, care shall be taken toavoid bringing loads on to any concrete until it has hardened sufficientlyto carry such loads.

c) Timber or other materials used for shoring the sides of excavations shall

be removed as the work proceeds except when ordered to be left in by theEngineer.

d) The Contractor shall, not later than four weeks before commencing anyexcavation, submit to the Engineer for inspection calculations andworking drawings for the proposed scheme of strutting and retaining thesides of the excavations and shall not proceed with the appropriate sectionof the works until receipt of the Engineer's written consent.

e) The receipt of such consent shall not relieve the Contractor of any of hisduties and responsibilities under the Contract.

3.3.5 Moisture Content of Backfilling Material or Imported Fill

a) During compacting the backfilling material or imported fill shall have auniform moisture content within 2 percent of the optimum for thecompaction plant employed or as may be directed by the Engineer aftertests. Where necessary the Contractor shall adjust the moisture content ofthe backfill either by drying out or by adding water. After such drying outor adding of water the backfill shall be thoroughly mixed until themoisture content is uniform. Should the material being placed as filling oras backfilling, while acceptable at the time of selection, becomeunacceptable to the Engineer due to exposure to weather conditions or dueto flooding or have become puddled, soft or segregated during the

progress of the works, the Contractor shall at his own expense removesuch damaged, softened or segregated material and replace it with freshapproved material.

b) When placing the filling or backfilling the Contractor shall make dueallowance for any settlement that may occur before the end of the Periodof Maintenance. Where necessary, the Contractor shall at the end of thePeriod of Maintenance remove any excess material or make up anydeficiency or backfilling to the specified levels.

3.3.6 Compaction of Backfilling Material or Imported Fill

Backfilling material or imported fill shall be placed in layers not exceeding thoselimits stated in Section 3.2.2.1. Each layer being well compacted by a 5 ton rollerbefore the next layer is placed. The density after compacting shall not be lessthan the maximum dry density obtained in test 12 of BS 1377-4:1990.

3.3.7 Trimming of Slope

a) The slopes of cuttings and embankments shall be trimmed by hand or byapproved mechanical means to uniform batters as shown on the drawings


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or as directed by the Engineer. A tolerance of plus or minus 100mmmeasured at right angles to the batter will be permitted.

b) Any rock or boulder appearing in the face of a cutting shall be trimmedback to within the tolerance specified above and in addition any such rockor boulder which in the opinion of the Engineer is unstable shall be

completely removed and the resulting void filled with compacted materialto the approval of the Engineer.

3.3.8 Draining of Excavation

a) All excavations shall be kept free of water at all times and the Contractorshall provide efficient appliances and drains for dealing with water to thesatisfaction of the Engineer.

b) Particular care shall be taken to keep dry, rock and other surfaces againstor upon which concrete may be deposited, and proper precautions shall betaken to prevent the leaching out of cement or otherwise damaging unset

concrete.

c) Should any existing drains or ditches be disturbed during the Contractor'soperations they shall either be made good or diverted.

3.3.9 Excavation in Rock and Boulder Rock

The Contractor shall notify the Engineer on each occasion he considers that he isentitled to payment for excavation in rock and boulder rock and shall not fill anyexcavation concerned until it has been inspected by the Engineer. No paymentfor excavation in rock or boulder rock shall be made unless the Engineer hasinspected the excavation and certified in writing the quantity involved.

3.3.10 Explosives and Blasting

a) The Engineer shall be notified by the Contractor in advance of all sectionsof the works where it is proposed to use explosives, and the Engineer shallhave power to prohibit or restrict their use where, in his opinion, it isnecessary to do so to safeguard persons, property, existing or new work orstrata on which it is proposed to found new work. The Contractor shallobtain all necessary licences and permission covering the purchase anduse of explosives, and shall meticulously observe the requirements ofGovernment and local authorities.

b) The Contractor shall have no claim against the Employer arising from anyrestriction or prohibition on the use of explosives by the Engineer or theAuthorities.

c) The Contractor shall provide a proper secure magazine for the storage ofexplosives to the satisfaction of the Engineer, and they shall be handledonly by men experienced and trained in their use, and strictly inaccordance with the manufacturer's instructions.


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d) When using explosives in excavation, should the rock be shattered ordisturbed outside the limits of excavation shown on the drawings, thecontractor shall cut out such disturbed sections to a depth approved by theEngineer and make good with mass concrete. Such further excavationshall be held to be "Excess Excavation" and the Contractor shall supplymass concrete at his own expense.

3.3.11 Unsuitable Material

a) When the specified levels or limits of excavation are reached the Engineerwill inspect the ground exposed and if he considers that any part of theground is by its nature unsuitable he may direct the Contractor to excavatefurther and refill to the specified levels or limits with mass material. Suchfurther excavation shall be held to be extra excavation and shall bemeasured as such.

b) Should the material forming the bottom of any excavation, whileacceptable to the Engineer at the time of his inspection, subsequentlybecome unacceptable to him due to exposure to weather conditions or dueto flooding or have become puddled, soft or loose during the progress ofthe Works, the Contractor shall remove such damaged, softened orloosened material and excavate further by hand. Such excavation shall beheld to be excess excavation and carried out at the Contractor's ownexpense.

3.3.12 Disposal of Surplus Excavated Material

All excavated material not required for backfilling and unless otherwise stated

shall be removed from site to a suitable tip, to be provided by the Contractor whois to include in his prices for all charges and temporary spoil heaps that may berequired.

3.3.13 Trench Excavation In Existing Roads or Well Used Tracks

Where trench excavation is required across existing surfaced roads or well used

tracks the Contractor shall provide and maintain a suitable graded diversioncomplete with adequate signing all to the approval of the Engineer. Suchexcavations shall be backfilled with backfilling material or imported fill. Wherethe road has a sealed surface this shall be replaced after the backfill has been

suitably consolidated.

3.3.14 Protection of Services

The Contractor shall ascertain for himself the location of all permanent mainservices, and shall maintain and protect these where affected by the Works andshall in no way interfere with these permanent services without receiving thewritten permission of the Engineer.

3.3.15 Trenches Not To Be Left Open


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Soil under piers, utility pipe openings, floor drains and electrical conduitpoints shall be thoroughly flooded with the chemical emulsion at anapproximate rate of 25 to 30 litres. If drainage pipes are laid along thewalls and the chemical barrier laid as per Stage 3 is disturbed/broken,additional treatment to such areas will be necessary. Precautions must betaken not to disturb the treated areas by re-levelling, excavation or earth

filling, as this will break the chemical barrier. If such a situation arises thedisturbed area must be treated again in order to restore the chemicalbarrier.

End of SectionEnd of SectionEnd of SectionEnd of Section


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4.0 CONCRETE WORKS

4.1 General4.1.1 Description of works

This section covers manufacture, testing and use of structural qualityconcrete and consists of providing all plant, labour and materials and ofperforming all operations in connection with plain and deformed bar

reinforcement and steel fabric to be cast into concrete.

To be read with preliminaries/general conditions.

4.1.2 Related Standards

All materials methods and workmanship shall comply with the relevantBritish Standards and Codes of Practice.

General Specification November 2001, Sultanate of Oman: ConcreteWork

In general the work shall be carried out in accordance with ConcreteWork Specification, Sultanate of Oman, and as per the following codes.

4.1.3 Reference documents for concrete work

BS 12: 1991 Specification for Portland Cement

BS 812 Testing aggregates

BS 882: 1992 Specification for aggregates from naturalsources for concrete.

S 1305: 1974 Specification for batch type concretemixers.

BS 1704: 1985 Specification for solid stem generalpurpose thermometers

BS 1882 Methods of testing concrete


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BS 3148: 1980 Methods of test for water for makingconcrete

BS 4550 Methods of testing cement

BS 3963: 1974 Method of testing the mixing

performance of Concrete mixers.

BS 5075 Concrete admixtures.BS 5328: Part 1: 1991 Guide to specifying concrete

BS 5328: Part 2: 1991 Methods of specifying concrete mixes

BS 5328: Part 3: 1990 Specification for the procedures to beused in producing and transportingconcrete.

BS 5328: Part 4: 1990 Specification for the procedures to beused in sampling, testing and assessingCompliance of concrete.

BS 8000 Part 2 Code of Practice for concrete work 1990

BS 8110 Structural use of concrete

a) Part 1: 1997 Code of Practice for design and

construction

b) Part 2: 1985 Code of Practice for special

circumstances.

4.1.4 Reference documents for reinforcement work:

BS 4449: 1988 Specification for carbon steel bars for thereinforcement of concrete

BS 8666: 2000 Specification for scheduling dimensioning,bending and cutting of steel reinforcementfor concrete.

BS 4483: 1985 Specification for steel fabric for thereinforcement of concrete.

BS 6744: 2001 Specification for austenitic stainless steelbars for the reinforcement of concrete.

4.1.5 General Approvals

4.1.5.1Materials


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Submit samples of all materials proposed for use in the works to theContract Administrator for approval. Include specifications, tests andname of source and supplier for the materials. The Management Teamand the Contract Administrator shall have access to all the sources ofsupply for the purpose of inspection and taking samples.

Obtain the Contract Administrators approval in writing for allmaterials included in the concrete works before commencement ofconcrete works. Any change of materials or source of supply requiresapproval by the Contract Administrator in writing. The ContractAdministrator and/or the Management Team has the right to reject anymaterial that in his opinion does not meet the required standard for theWorks.

4.1.5.2 Execution

The Works Contractor is required to obtain concrete from an

approved readymixed concrete batching facility.

The Works Contractor shall submit detailed descriptions of allwork methods, equipment and plant intended to be used for theworks to the Contract Administrator for approval. The WorksContractor shall Execute all trials and tests as specified andsubmit detailed reports for all trials and tests to the ContractAdministrator for approval.

The Works Contractor shall obtain the Contract Administratorsapproval in writing for the arrangements for mixing concrete.Any changes in the arrangements will be required to be approved

by the Contract Administrator in writing. The ContractAdministrator has the right to reject any mixing arrangementsthat in his opinion are not acceptable.

4.2 Material

4.2.1 General

All materials for the works shall be new and have the properties asspecified and approved.

The approved samples shall be representative for the deliveredmaterials. All materials shall be delivered to the site well in advance ofuse to enable testing on site of the delivered materials.

The materials shall be independently tested or provided with originaltest certificates from the manufacturer for approval of the ContractAdministrator.


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The materials shall be tested regularly and at a frequency necessary toensure continuous compliance with the specification and not less thanspecified as a minimum. New deliveries shall be tested before use.

Materials shall be transported, handled and stored on the site orelsewhere in such a manner as to prevent damage, deterioration or

contamination.

Materials not approved shall be removed immediately from the site atthe Works Contractors expense.

4.2.2 Cement

All cement shall be Ordinary Portland Cement from an approvedsource and shall comply with:

BS 12

ASTM Type 1

The heat of hydration at 7 days (ASSTM C-186) shall be:

Maximum 325 kj/kg

The cement shall be low alkali cement and contain:

Max. 0.6% (Na2 O+0.658 k2O)

The specific surface (BS 4550) shall be:

Max. 325 m2/kg.

The tricalcium aluninate content shall be as high as possible withoutcreating undesired effects and shall not cause disintegration of theconcrete from reaction with sulphates. The cement shall contain:

Minimum 6% C3A

Maximum 12% C3A

Cement shall be delivered in the manufacturers sealed branded bags orbarrels. Each consignment shall be accompanied by the manufacturers

test certificate.

The certificate shall include the following information:

The manufacturers bulk average test results for the manufacturingbatch including chemical composition and physical propertiesdetermined in accordance with the approved specification for thecement.


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The date and place of manufacturing of the cement.

The date and place of original loading and the date of intendeddelivery to the site

Damaged bags or barrels and any cement Contract Administrator

considers unsatisfactory shall be rejected. Cement affected by water ordamp conditions shall be rejected.

Rejected cement shall be removed from the site immediately.

Where bulk cement deliveries are proposed by the Works Contractor, theWorks Contractor shall provide all information concerning off-sitestorage and loading arrangements for approval of the ContractAdministrator.

All cement shall be stored and transported in a suitable way to keep it

dry and cool. The cement shall be stored in a dry weatherproof buildingor silo. It shall be ensured, that condensation in the storage does notoccur ever at high humidity. Bagged cement shall be stored off theground in an approved manner. Different types of cement shall be storedin separate areas, and shall be clearly marked.

4.2.3 Aggregate

i) General

All materials used as aggregates shall be obtained from an approvedsource known to produce aggregates for concrete of the required quality.

The aggregates shall not cause damage or weakening of the concrete.The materials shall be chemically inert, strong, hard, durable, of limitedporosity and free from adhering coatings, clay lumps, coal and coalresidues and organic or other impurities that may cause corrosion of thereinforcement or may impair the strength or durability of the concrete.

The maximum size of the aggregates shall not be larger than 1/5 of thesmallest dimension of the member to be cast or larger than 3/4 of thesmallest distance between items embedded in the concrete.

All aggregates shall be stored and handled in a manner that theaggregates do not segregate or be contaminated. The aggregates shallbe stored on a clean concrete slab with a slope effectively draining theslab. Each type and grading of aggregates shall be completely separatedfrom others by tight and durable walls of concrete or equal. The storedaggregates shall be covered with sheeting and provided with shading.The temperature in the aggregates shall be kept as low as possible.

ii) Fine Aggregates


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The aggregates shall be natural or crushed sand. Beach sand shall not beused.

The limits for deleterious substances and physical property shall complywith the following:

(M or F to BS 882)

GRADING: Percentage by mass passing BS sieve

Sieve Size Limits

5.00mm --2.36mm 65 - 1001.18mm 45 - 1000.60mm 25 - 100

0.30mm 5 700.15mm --

Fine material : Max. 3% by weight finerthan 75 microns

Shells : Max 1% voided shells

Chlorides : Max. 0.05% by weight acidsoluble Cl-

Sulphates : Max. 0.17% by weight acidsoluble SO3

Magnetite : Max. 2.5% by weight

Mica, loam,clay, silt,dust and anyvegetable orsaline orother impurities : Max, 1.0% by weight and

max. 3.0% by volume.

Absorption : Max. 2.0%MagnesiumSulphate

soundness

Weight loss : Max. 10% after five cycles

Organicimpurities : Colour lighter than reference

standard colour

Alkali


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Reactivity : Expansion less than 0.05%after 3 months.

Dryingshrinkage : Max. 0.05%

iii) Coarse Aggregates

The aggregates shall be crushed aggregates obtained from an approvedsource.

The limits for deleterious substances and physical property shall complywith the following:

GRADING: Percentage by mass passing BS sieve

Sieve Limits

20.00mm 90 10014.00mm --10.00mm 30 60

5.00mm 0 102.36mm --

Surface : Min. 90% with fractured faces.

Chlorides : Max. 0.02% by weight acid soluble Cl-

Sulphates : Max. 0.17% by weight acid soluble SO3.

Magnetite : Max 2.5% by weight

Combustibleparticles : Max 1.0% by weight

Absorption : Max. 1.5%

Flakiness index : Max. 25%

Clay lumpsand friable

particles : Max. 1.0%

Magnesiumsulphatesoundness : -

Weightloss : Max. 10% after five cycles

Alkalireactivity : Expansion less than 0.05%


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after 3 months

10% finesvalue : Min. 100 kN.

Drying

shrinkage : Max. 0.05%

4.2.4 Admixtures

Admixtures shall be used as specified and shall be approved beforeconstruction commences, and used strictly to manufacturersrecommendations. Make trial mixes and in consultation with theContract Administrator adjust the dosage and/or mix proportions inorder to give suitable properties in the fresh and hardened concrete.

Admixtures shall be products manufactured for use in concrete. Alleffects of the admixtures on the fresh and on the hardened concrete shallbe well documented by the manufacturer, and the admixtures shall haveproven record for use under similar conditions.

Admixtures containing chlorides or nitrates shall not be approved.

The Works Contractor is to submit detailed and comprehensivemanufacturers technical description and recommendation for handling

and use. When more than one admixture is to be used the compatibilityof the materials shall have been ascertained by tests and approved inwriting by the manufacturer(s).

Admixtures shall be handles and stored according to the manufacturersrecommendations. The materials shall be protected from anycontamination.

Plasticizers shall be used for all concrete, according to AASHTO M194.

The purpose of plasticizers is to increase the workability of the concrete,and at the same time to reduce the water content.

For all admixtures used a certificate shall be submitted. The certificateshall include the following details:

Type/Nature of admixture

Main Effect

Name of product

Supplier/Manufacturer


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General

Active components

Density, kg/l

Content of dry solids, %

Equivalent Na2O, %

Chloride ion content, %

pH value

Colour

Latest date of test and name and address of the testing laboratory

When more than one admixture is to be used and compatibility ofthe materials shall have been ascertained by tests and approved inwriting by the manufacture(s).

Admixtures shall be handled, stored and introduced to theconcrete according to the manufacturers recommendations. Thematerials shall be protected from any contamination.

All admixtures shall be approved by the Contract Administratoras a part of the concrete mix design.

The packing shall be marked with the name of the supplier, brandname (name of product), admixture type, date of manufacture andexpiry.

Side Effects

Normal side effects

Side effects when overdosed

Storage

Shelf life

Max/Min. allowable temperature

Other instructions (e.g. requirements for stirring)

Dosage

Max/Min. shall be specified as percent (%) by weight of the totalamount of cement.


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4.2.5 Silica Fume

Silica Fume shall be from an approved source, and shall comply withthe following:

The condensed silica fume shall be from an approved source, and shallcomply with the following:

The condensed silica fume shall have a content of:

Minimum 85% Si O2

and comply with:

Specific surface Min. 15,000m2/kg

Magnesium oxide (MgO) Max. 5.0%

Sulphur trioxide (SO3) Max. 4.0%

Soluble equivalent sodium oxide (Na2O)e Max. 1.5%

Chlorides (Cl) Max. 0.1%

Moisture Max. 1.5%

Loss of ignition Max. 5.0%

Fineness (more than 0.045mm) Max. 40%

The analysis of the Silica Fume shall be according to BS or ASTMStandards. Sodium oxide, moisture, loss on ignition and finess shall betested according to ASTM C311-77.

Silica Fume shall be stored and handled as cement.

4.2.6 Quality Control

The Works Contractor shall as a minimum record the check on

following items:

Materials test including all items mentioned in the Specification.

A material test is valid for only one month. Materials not usedwithin this period shall be removed or re-tested.

Check of delivery note and certificate of Silica Fume on arrivalto the Site for all deliveries.


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Regularly check temperature and humidity where the Silica Fumeis stored. Minimum once every working day.

4.2.7 Water

Water for use in concrete and mortar and for curing shall be obtainedfrom an approved source. The water shall not affect the strength anddurability of the concrete or the mortar and shall not creatediscolouration of the hardened concrete or affect the reinforcement.

The water shall be clean, desalinated or potable water which complieswith the following:

PH value : Max. 8.0 Min. 7.0Total dissolved solids : Max. 2000 ppmSuspended solids : Max. 2000 ppm

Chloride as NaCL : Max. 500 ppmChloride as Cl- : Max. 250 ppmSulphates as SO3 : Max. 350 ppmAlkali HCO3/CO3 : Max. 500 ppm

Water shall be stored in clean covered containers and protected fromany contamination.

Water shall be kept cool and the temperature of the water when added tothe concrete shall be the lowest possible.

In hot periods crushed ice from an approved source of water may be

used if approved by the Contract Administrator.


The Works Contractor shall, as a minimum, record the check onfollowing items:

Laboratory test of water.

Temperature of water just before concrete mixing.

4.2.9 Fibres

Fibres for concrete shall be non-ferrous type that have no effect on thefinish of the concrete surface.

Fibres for concrete shall have proven record of use in concrete mixes.The fibres shall have no water absorption and have a high resistance toacids and alkalies.


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The Works Contractor shall submit documentation for the material andtest report for its use in concrete to the Contract Administrator forapproval. The documentation shall include information on type of fibrematerial, fibre dimension, specific surface of fibres, and eventualchanges in the fibre during its service life.

Polypropylene fibres shall be finely cut and specifically treated forenhanced bond. The length and diameter of the fibres shall be optimal inorder to minimize cracking in the concrete and without creating balls inthe mix.

Specified quantity of fibres (typically 0.6 to 0.9 kg/m3) shall be added tothe concrete using a method ensuring uniform distribution. The methodof adding fibres shall be according to the manufacturersrecommendation.


1) Cement


Materials tests including all items mentioned in thespecification and the BS and ASTM standards. A materialtest is valid for only one month.

Check of delivery note and certificate of cement on arrival tothe site for all deliveries.

Regularly check of temperature and humidity where thecement is stored. Minimum once every working day.

2) Aggregates


Materials test including all items mentioned in thespecification and according to the mentioned BS and ASTMstandards. The frequency of the tests shall be according to2.2.2.10.

Check of delivery notes of all types of aggregates on arrivalto the site for all deliveries.


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Check of temperature in the aggregates during concretemixing.

3) Water

The Works Contractor shall, as a minimum, record the check on

following items:

Laboratory test of water.

Temperature of water during concrete mixing.

4) Admixtures

The Works Contractor shall, as a minimum, record check onfollowing items:

Check of delivery note on arrival to the site for all deliveries.

4.2.11 Materials tests and Frequencies

Required Test Test Method Frequency

Grading BS 812, Part 103 Each delivery, each 2weeks or per 100m3whichever is morefrequent.

Material finer than 0.075 BS 812, Part 103 -do-mm

Clay lumps friable ASTM C142 -do-particles

Organic impurities ASTM C40 -do-

Water absorption ASTM C128/C127 Each day of concreting

Specific gravity ASTM C128/C127 Each delivery, each 2

weeks or per 100m3which ever is morefrequent.

Shell content BS 812, Part 106 -do-

Particle shape BS 812, Part 105 -do-

Acid soluble chlorides(Cl-)BS 812, Part 117 Each delivery, each


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number and other applicable data that will identify the materialwith the certificate issued for the lot of steel.

The Works Contractor shall submit certificates for each type andsize of bars showing each number from which the bars have beenfabricated.

Further test to determine the compliance of the ChemicalComposition and Physical Properties to the mill tests, as deemednecessary by the Contract Administrator, shall be carried outrandomly to reinforcement delivered to site.

The method of sampling and testing and the frequency of testsshall be in accordance with BS 4449, or as required and agreedby the Contract Administrator.

All reinforcement shall be clean and free from materials that may

cause corrosion of the reinforcement or disintegration of theconcrete. The steel bars shall be free from pitting, loose rust,mill scale, paint, oil, grease or other materials that may impairthe bond between the concrete and the reinforcement.

Sheets of mesh fabric shall be flat unless specified as bent, andany tendency to curve or twist shall be corrected by the WorksContractor before fixing. Mesh fabric shall not be supplied inrolls.

Reinforcement shall be stored on properly constructed racks atleast 150mm above ground level. The storage, cutting and

bending of steel reinforcement shall be carried out under coveron an approved, free draining concrete platform. All steelreinforcement at site shall be protected from humidity and saltladen dews by 1000g polythene sheeting or equivalent approved.

4.2.12.2 Quality Control

As a minimum record the check on following items:

Check of steel certificates for all types and sizes of bars.

Check of delivery notes for all types and sizes of bars.

Visual inspection of steel when delivered to the site.

Check of storage for steel.

4.3 Workmanship Concrete

4.3.1 General


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Determination of the free water/cement ratio shall include silica fumewhenever used, with an activity factory of 2.0. Calculation of the freewater/cement ratio is then:

W/C = water (1.0 cement + 2.0 silica fume)

The specified quantity of silica fume as % cement content is in additionto the cement e.g. where cement is 350 kg/m3, silica fume will bemin.24.5 kg.

4.3.3 Mix Design

The Works Contractor shall submit a design proposal for each type ofconcrete to the Contract Administrator for approval well in advance ofcommencement of concreting on the side.

The proposed mix design shall include but not be limited to the

following:

Weight and density of all materials

Grading for each type of aggregates

Grading for the combined aggregates

Calculation of fine materials

Calculation of free water/cement ratio

Calculation of content of alkalies

Calculation of content of chlorides

Calculation of content of sulphates

Estimation of air content

Estimation of characteristic strength

Estimation of workability

All the necessary Test Certificates of the used materials

The Works Contractor shall design the concrete mixes with the lowestpossible content of cement necessary to meet the requirements of thespecified type of mix. The content of cement shall not exceed 500 kgper cubic metre.

The concrete mixes shall be designed with a grading of the combinedaggregates requiring a minimum of water to create workability andcreating a homogeneous concrete with a high density.

The total chloride content in the concrete expressed as a percentage acidsoluble chloride by weight of cement shall not exceed 0.15% for SRCand 0.3% for OPC.

The total sulphate content in the concrete expressed as percentage byweight of cement shall not exceed 4.0% acid soluble SO3.

4.3.4 Trial Mixes


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Laboratories independent of both the ready mix concrete supplier and theWorks Contractor must be used. Execute the laboratory tests and trialmixes required to demonstrate that the proposed mix design for all typesof concrete mixes meets the requirements.

The laboratory tests shall be made on concrete samples from the trialmixes. The tests shall include determination of the following properties.

The Works Contractor shall make three trial mixes on the site for eachtype of concrete mix using the plant, equipment, batching and transportmethods intended for use in the works.

The requirement to compressive strength shall be verified by taking sixcubes from each of the three mixes. The test cubes shall be prepared andcured in accordance with BS 1991, Part 3. Two cubes shall be testedafter 7 days of maturity, and four after 28 days of maturity.

The results of the tests of compressive strength for the trial mix shall be

approved, if the 28 days cube strengths for ALL test cubes exceed thespecified characteristic strength minus 3 N/mm2, and if the averagecompressive strength of the four cubes tested at 28 days exceeds thespecified characteristic strength by at least 3 N/mm2.

No concrete mix shall be placed in permanent works until the mix hasbeen approved in writing by the Contract Administrator. No approval bythe Contract Administrator shall relieve the Works Contractor of theresponsibility of maintaining the required quality.

Any change in the mix design or any change in materials, type, source ofgrading requires approval by the contract Administrator and execution ofa new trial mix.

All costs connected with laboratory tests, trials mixes, mix design andpractical tests shall be included in the Works Contractors price for theworks.

4.3.5 Mixing of Concrete

Concrete shall be weigh batched and mixed in an approved mixing

machine fitted with approved water metering device. Volume batchingwill not be allowed.The weighing and water-dispensing mechanisms shall be maintained ingood order. Their accuracy shall be maintained within the tolerancesdescribed in BS 1305 and checked against accurate weights and volumeswhen required by the Contract Administrator. The batcher mustautomatically record quantities actually placed in each batch.

The accuracy of the measuring equipment shall be within +3% of thequantity of cement, water or aggregates being measured and within


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k+5% of the quantity of silica fume and admixtures. The weights of thefine and coarse aggregates shall be adjusted to allow for the free watercontained in them.

The water to be added to the mix shall be reduced by the quantity of freewater contained in the fine and coarse aggregates, which shall be

determined by the Works Contractor before mixing begins, and furtheras the Contract Administrator.

The temperature of all materials shall be measured before dischargedinto the mixer. The temperature of the fresh concrete shall be measuredwhen discharged from the mixer.

Unless otherwise agreed by the Contract Administrator, concrete shall bemixed in a batch type mixer manufactured in accordance with BS 1305or in a batch type mixer, a specimen of which has been tested inaccordance with BS 3963 and having a mixing performance within the

limits of Table 6 of BS 1305. Where appropriate, the batch capacity,method of loading, mixing time and drum speed shall conform to thedetails furnished in accordance with the requirements of BS 3963 for themix which corresponds most closely to the mix proportions being used.

The mixing blades of pan mixers shall be maintained within thetolerances specified by the manufacturer of the mixer, and the bladesshall be replaced, when it is no longer possible to maintain the tolerancesby adjustments.

Mixers which have been out of use for more than 30 minutes shall bethoroughly cleaned, before any fresh concrete is mixed in the machine.

Mixing plants shall be thoroughly cleaned before changing from onetype of mix to another or before changing from one manufacture ofcement to another.

Controls shall be provided to ensure that no additional water can beadded during mixing. The entire batch shall be discharged before themixer is recharged. The mixing and tempering of stiffened concreteshall not be permitted.

A concrete slab with adequate drainage shall be provided as a workingplatform, unless alternative arrangements are specifically permitted by

the Contract Administrator.

The concrete shall be placed in its final position within 60 minutes of thetime, when the cement first came into contact with water or wettedaggregates. This time limit may be extended by adding suitableretarding admixtures in concrete, subject to approval by the ContractAdministrator. Detailed technical information on such admixtures shallbe submitted to the Contract Administrator for approval, well in advanceof their proposed use in concrete.


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Mark on the cube

Signature of the person responsible for the test

The cost of taking and testing concrete and materials required toensure compliance with this specification shall be borne wholly

by the Works Contractor.

Further random concrete samples, as determined by the ContractAdministrator, shall be made and tested at the owners laboratoryin Muscat, or any other lab, without any additional cost to theowner.

Should the concrete supplied not comply with the characteristicstrength requirements the Contract Administrator may instructthe removal and replacement of the concrete or other remedialaction to be taken. Any such removal or remedial action will be

carried out at the Works Contractors own expense and paymentwill not be made for such elements until the removal andreplacement or remedial action is completed, to the satisfactionand approval of the Contract Administrator.

4.3.6 Transportation and Placing of Concrete

The Works Contractor shall inform the Contract Administrator inwriting 24 hours before commencement of concreting works givingcomplete details of the works. The Works Contractor shall notcommence the works without written approval from the ContractAdministrator of excavations, formwork, reinforcement, arrangements

for plant and materials on site, installation of accessories, etc. Anyconcrete placed before obtaining such approval shall be rejected.

Controls shall be provided to ensure that no additional water can beadded during mixing. The entire batch shall be discharged before themixer is recharged. The mixing and tempering of stiffened concreteshall not be permitted.

The concrete shall be placed in its final position within 60 minutes of thetime, when the cement first came into contact with water or wettedaggregates. This time limit may be extended by adding suitable

retarding admixtures in concrete, subject to approval by the ContractAdministrator. Detailed technical information on such admixtures shallbe submitted to the Contract Administrator for approval, well in advanceof their proposed use in concrete.

The formwork or area of disposition shall be cleaned as specified.Constructional plant and materials required, or which may be requiredduring the concreting work and for curing shall be on site and fullyprepared before concreting commences.


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All accessories shall be installed, and formwork for holes, chases, etc.shall be provided as specified.

The concrete shall be transported from the mixer to the point of placingas rapidly as practicable by methods that will maintain the required

workability and will prevent segregation, loss of any constituents oringress of foreign matter or water.

The concrete shall be deposited as close as practicable to its finalposition to avoid rehandling or moving the concrete horizontally byvibration.

Except where otherwise agreed by the Contract Administrator, concreteshall be deposited in horizontal layers to compacted depth not exceeding400mm where internal vibrators are used or 300mm in all other cases.

Unless otherwise agreed by the Contract Administrator, concrete shallnot be dropped into place from a height exceeding 1.5 metres. Whentrunking or chutes are used they shall be kept clean and used in such away as to avoid segregation.

Concrete shall be deposited continuously. No concrete shall be placedagainst concrete which has hardened sufficiently to cause seams, planesat weakness or cold joints.

If for unforeseen reasons it is necessary to stop concreting beforecompletion of the pour, then construction joints as specified shall beformed and further concreting shall be suspended for at least 24 hours

unless otherwise approved in writing by the Contract Administrator.

The concrete shall be placed in its final position within one hour frombeing discharged from the mixer, or before that if the initial set hasstarted.

Cutting and chasing of hardened concrete shall not be permitted withoutthe Contract Administrators approval. The Works Contractor shallprovide openings, mortises, chases, sleeves, etc., and fix bolts, anchors,etc, in concrete as work proceeds and support embedded items againstreplacement. Items cast shall be filled with readily removable materials

to prevent concrete ingress.

All receptacles used for the transport and deposition of the concrete shallbe kept clean.

The Works Contractor shall obtain the Contract Administratorspermission before concreting in periods where the daily max. air shadetemperature exceeds 30 deg. C, and shall take appropriate precautions toprevent early setting and to ensure that the concrete temperature whenplaced does not exceed 30 deg. C or 28 deg. C where cement


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replacement is used. The Works Contractor shall control thetemperature in the hardening concrete and in previously cast concrete atconstruction joints.

Under no circumstances should concrete be placed when ambienttemperature exceeds 45 deg. C.

Such appropriate precautions may include but are not limited to thefollowing:

Cooling of ingredients

Adding ice to concrete mix

Cooling of existing structure before concreting by spraying coolwater or by an arrangement of chillers

Cooling of hardening concrete and existing structures during curing

No concreting shall be carried out in rain. The re-mixing or retemperingof stiffened concrete is not permitted.

The Contract Administrator can reject any concrete which he considersto have been inadequately mixed, or in which the ingredients havesegregated, or which is no longer capable of being effectively placed orcompacted.4.3.6.1 Quality Control


Completion of excavations, formwork, reinforcement andarrangement for plant.

Time when the concrete is discharged from the mixer andtime when placed in final position for each batch.

Air shade temperature and temperature of concrete whenplaced in final position in air shade temperatures above30 deg. C.

Special cooling arrangements if required.

4.3.6.2 Hot Weather Precautions

Hot weather precautions shall be taken at the concrete mixingplant and during transport in order to comply with specifiedtemperature limits of fresh concrete at any time of the year.CIRIA Special Publication 31 and ACI 305R are applicable for


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examples of good practice, always subject to stricterrequirements which may be stated in this Specification or inother contract documents.

The overall maximum temperature limit for fresh concrete whenstarting to place it in its final position shall be 30 deg. C, except

where cement replacement is used whereby the maximumtemperature shall be 28 deg. C.

To ensure compliance, the target max temperature for freshconcrete at the mixing plant shall be set lower than this overallmaximum limit, taking into account the variations in ambientconditions, transport time, waiting time, etc.

4.3.6.3 Compaction

All concrete shall be compacted using vibrators. The size and

type of vibrator shall be selected in relation to the size of thestructure and free space inside formwork and between bars. Thevibration equipment shall be approved by the ContractAdministrator.

Internal vibrators shall be of the immersion type with a frequencyof not less than six thousand vibrations per minute and sufficientamplitude to consolidate the concrete effectively. The WorksContractor shall provide at least 50% duplication of all vibration

equipment as standby during any period of concreting.The vibration shall be carried out only for the necessary timerequired for thorough compaction of all parts of the concrete.

The Works Contractor shall carefully supervise the compactionwork and ensure that excessive vibration, vibration of steel andform, and moving of concrete leading to defects in the concrete,shall be avoided.

Do not use vibrator to make concrete flow horizontally intoposition, except where necessary to achieve full compactionunder void corners and cast in accessories and at vertical joints.

The Works Contractor shall as a minimum record check onfollowing items:

Supervision of vibration of concrete.

4.3.7 Curing

Casting and curing of the concrete shall be planned and executed in sucha way, that the concrete during hardening is protected against harmfulinfluence from the environment and from heat of hydration.


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All methods and materials for curing shall be approved by the ContractAdministrator prior to commencement of the works. All surfaces shallbe protected, which are not sealing the surface completely fromevaporation.

The method of protection shall as a minimum include:

Protection from direct sunlight of concrete surfaces andformwork by shades.

Protection with close fittings polythene membrane immediatelyafter casting and compaction is completed.

Protection after finishing operations with absorption mat offabric laid directly onto the concrete in unbroken sheets withsubstantial lap joints. The mats shall be kept continuously wetand covered with a white polythene membrane. The polythene

sheets shall be unbroken with substantial close fitted lap joints.Sheets shall be fixed in full contact with the concrete surface andkept in place at all times during curing.

The water for curing shall be of equal quality as for the water concrete.

The curing period for protection against evaporation shall be decidedbased on the type of concrete and the air temperature and humidity. Useof chemical compounds for curing shall not be permitted, unless

specifically approved by the Contract Administrator.

The protection period shall be minimum 10 days.


The Works Contractor shall as minimum record the check onfollowing items:

Time when polythene membrane is placed and removed.

Time when absorption mat and polythene membrane isplaced and removed.

Wetting and check of efficiency of polythene cover in thecuring period.

4.3.8 Temperature Control

The temperature in the fresh and in the hardening concrete shall becontrolled if required by the Contract Administrator in order to preventdefects from high temperature during hydration and from movementscaused by temperature differences.


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The Works Contractor shall plan the works in order to minimizedeformation and stresses from restraint in thermal movements. If thedifference between the mean temperature of the cast concrete and thetemperature of previously cast concrete does not exceed 12 deg C, itmay be acceptable, dependent upon the actual degree of restraint to

thermal movement.

Appropriate precautions shall be made for cooling the recently placedconcrete and previously cast concrete adjacent to the newly castconcrete. These methods may include but not be limited to:

Cooling the ingredients for the concrete.

Adding ice to the concrete mix.

Keeping the concrete cool during transportation by shading or

insulation.

Cooling the concrete in the curing period by spraying cool water;cooling the surrounding air using chillers and insulation and coolingthe concrete using cast-in cooling pipes.

The cooling arrangements must not create temperature differences in theconcrete that could result in damaging the concrete. The temperaturecontrol arrangements and the methods of cooling the concrete shall beapproved by the Contract Administrator prior to commencement of theworks.

Exposed areas of newly placed concrete should be protected from directsunlight by appropriate shading, installed to the satisfaction of theContract Administrator.

4.3.9 Concrete Tolerances

a) The following tolerances shall not be exceeded:-

All setting out dimensions, lengths of beams nd slabs,storey heights 6mm

Cross-sectional dimensions of concrete members 6mm

Surface levels of floor slabs - Generally (in 10 mof length) 6mm

- Local undulations 3mm

Plumbs of columns and walls - In a storey height 6mm- In full building height 20mm

Variation in size and location of openings,


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sleeves and embedded fixtures 6mm

Variation in stairs In stairs In rise 3mm- In tread 6mm

b) Regardless of the tolerances permitted, the Contractor shall

consider building details that adjoin each other, since these maycall for even finer tolerances.

4.4 Workmanship Reinforcement

4.4.1 General

The Works Contractor shall prepare his own bar list and bendingdiagrams in accordance with BS 4466 from the information given on thedrawings and in the specification. The Works Contractor shall beresponsible for ensuring that correct information is given when ordering

reinforcement. Copies shall be submitted to the Contract Administratorfor his information at least two weeks in advance of placement of thesteel but this shall not relieve the Works Contractor of anyresponsibility.

The Works Contractor shall provide and submit to the ContractAdministrator for approval any working drawings additional to thecontract drawings which may be found necessary for the production ofbar schedules or for completion of the works. The approval of working

drawings shall in no way relieve the Works Contractor of responsibilityfor the correctness of such drawings.

The Works Contractor is responsible for the reinforcement, and shallensure that all reinforcement is checked by a competent person. TheWorks Contractor shall notify the Contract Administrator well inadvance about portions of reinforcement work ready for inspection andshall keep a detailed record of the planning and control of thereinforcement work.

4.4.2 Cutting and Bending

Dirt, rust, concrete, scale, paint, oil, grease, salts, etc. shall be removedfrom the reinforcement by grit blasting. Only grit blasting will be

approved.

Reinforcement shall be cut and bent within the dimensional tolerancesgiven in BS 4466. Bars shall be bent cold by hand or by using anapproved hand or power operated bending machine. When bending, thereinforcement shall be subjected to a constant even load and not animpact load.

Welding of reinforcement will only be allowed with the specific writtenpermission of the Contract Administrator.


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Bar types, sizes and placement shall be shown on the drawings. Bendingdimensions shall be in accordance with BS 4466.

Bars incorrectly bend shall not be used. Hot rolled high yield steel barsshall not be straightened or bent again having once been bent.

No reinforcement shall be bent when in position in the works withoutapproval, whether or not it is partially embedded in hardened concrete.

The minimum diameter of the former shall be:

for mild steel (BS 4449) 4 x d

for high yield steel (BS 4449) 4 x d

for cold worked steel (BS 4461) 6 x d

4.4.3 Labelling and Storage

All bars and bundles of bars shall have a waterproof label securelyattached stating the drawing number and bar mark.

Reinforcement shall be stored in a manner and place such that it is kept

free from damage and mud, oil and any contaminants likely to impair itsperformance within the concrete.


The Works Contractor shall as minimum record the check onfollowing items:

Visual inspection of bent steel.

4.4.4 Fixing of Reinforcement

Bars in contact shall be firmly secured to each other with approvedbinding wire or proprietary clips of a type approved by the Contract

Administrator. Binding wire shall be black annealed mild steel wirediameter 1.5mm free from rust or other contaminants. Thereinforcement shall be fixed accurately in position so that reinforcementis in the correct position in relation to the formwork to give the specifiedconcrete cover.

The reinforcement shall be fixed securely in position so that it will notbe displaced during the passage of Works Contractors traffic, theplacing and compaction of the concrete or any related operations.


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Reinforcement shall be securely fixed in position with a dimensionaltolerance of 20mm in a direction parallel to a concrete face and within atolerance of 5mm at right angles to a face, provided that the cover is notthereby decreased below the minimum specified or otherwise shown onthe drawings.

Care shall be taken to ensure that projecting ends of ties or clips do notencroach into the concrete cover.

The following clear cover to all steel in cast in-situ concrete includinglinks shall apply:

Pad footings, columns below ground,ground beams, ground slabs earth face to walls 75mm

Columns, beams, walls, slabs, stairs,

external exposure 40mm

Columns, beams, walls, slabs, stairs,internal exposure 40mm

Coastal structures 75-100mm

The correct cover shall be maintained by the use of speciallymanufactured high quality impermeable concrete or mortar spacers. Site

manufactured blocks shall be well compacted and cast of approvedrepair mortar and water cured for a minimum of 7 days after casting andshall have a 30 minute absorption of less than 3.5% by weight. Concrete

spacers shall be similar in strength, durability and appearance to thesurrounding concrete.Samples of spacers shall be submitted for approval at least 14 daysbefore it is intended to place concrete.

Any wire cast into the spacer blocks shall be positioned well away fromthe exposed surface and shall be of stainless steel. Spacers fixed toparallel reinforcement bars shall not be located in a line across a section.Timber, stone, plastic or metal spacers will not be permitted.

The top reinforcement in slabs shall be rigidly supported by mild steel

chairs from the bottom reinforcement. Chair spacing shall be 1.0mcenters in both directions or less if required for working loads by smalldimensions or more by large dimensions.

Starter bars must be securely fixed to the reinforcement in the parentconcrete and accurately located to maintain the specified cover.

Reinforcement cages assembled before fixing shall be protected againstthe weather and shall be stored and transported carefully so that nodistortion or contamination may occur.


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Laps and joints not shown on the drawings shall be approved by theContract Administrator. Laps are to be staggered in such a manner thatmaximum one third of the bars are lapped in the same section.Otherwise the lap length shall be increased by 50%.

Mechanical splices shall not be used.

Quality Control

The Works Contractor shall as a minimum record the check on followingitems:

Visual inspections of laps.

4.5 Workmanship Formwork

4.5.1 General

Formwork for concrete shall be rigidly constructed of approvedmaterials and shall be true to the shape and dimensions described on theworking drawings. Steel or plywood forms or forms of other materialsmay be used with the approval of the Contract Administrator.

The formwork design shall be the sole responsibility of the WorksContractor, who shall submit his design for approval to the ContractAdministrator before construction commences.

Loadings design and construct formwork to withstand worstcombination of:

1. Total weight of formwork, reinforcement and concrete.2. Construction loads including dynamic effects of placing,

compacting and construction traffic.3. Wind loads.

Propping: Provide adequate propping to prevent deflection and damageto the structure. Carry down such props to bearings strong enough toprovide adequate support.

4.5.2 Design and Construction

The design of formwork shall be the sole responsibility of theContractor. However, the following upward cambers are suggested tothe formwork:

i) Cantilevered slabs 3mm to every 1.5m of spanii) Cantilevered beams 6mm to every 1.5m of spaniii) Slabs over 3m span 3mm to every 3m of spaniv) Beams over 6m span 6mm to every 3m of span but not

exceeding 40mm.


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Faces in contact with concrete shall be free from adhering grout,projecting nails, splits, or other defects. Joints shall be sufficiently tightto prevent the leakage of cement grout and to avoid the formation of finsand other blemishes. Faulty joints shall be caulked. 20mm by 20mmchamfers shall be formed on the external corners of concrete members,

unless otherwise specified.

Opening for inspection of the inside of the formwork and for the escapeof water used for washing out, shall be formed so that they can beconveniently closed before placing the concrete.

Connection shall be constructed to permit easy removal of the formworkand shall be strong enough to retain the correct shape duringconsolidation of the concrete.

Formwork shall be fixed in perfect lines, grades and dimensions, with no

crevices at joints. It shall be securely braced, supported and wedged soas to retain its position without displacement or deflection during theplacing and compaction of concrete. All joints shall be either horizontalor vertical, unless otherwise required.

In long spans, the anticipated deflection due to the effect of self-weightshall be accurately computed by the Works Contractor and taken intoaccount in the design of formwork such that the finished concretemember shall have true surfaces conforming to lines, planes and

elevations shown on drawings. If adequate foundations for shores arenot secured, trussed supports shall be provided by the Works Contractor.

Cast in metal ties and anchors shall, if possible, be avoided. Wheremetal ties and anchors are required, they shall be of stainless steel orremovable bolts located clear of the reinforcement by a distance equal tothe thickness of the concrete cover provided in the member. Thearrangement shall be to the satisfaction and approval of the ContractAdministrator.

An approved mould oil or other material shall be applied to faces offormwork to prevent adherence of the concrete. Such coatings shall beinsoluble in water, non-staining, and non-injurious to the concrete.Liquids that retard the setting of concrete shall be used only when

approved. Mould oil, retarding liquid, and similar coatings shall be keptfrom contact with the reinforcement or previously cast concrete.

Before any concrete is placed, forms shall be properly cleaned bywashing out with water and/or air under pressure to remove sawdust,shavings, metal and other foreign matter. All water shall then be drainedand mopped out from the formwork. In no case shall concrete be placedin the forms until such forms have been approved by the ContractAdministrator. Such approval shall not relieve the Works Contractor ofhis responsibility for the formwork.


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Details of any fixtures to be cast into the concrete shall be to theapproval of the Contract Administrator. No fixtures shall be attached tothe concrete by shot-firing without prior permission of the ContractAdministrator. Notwithstanding any such authorization, the WorksContractor shall take full responsibility for any such damage to the

structure and make good to the satisfaction and approval of the ContractAdministrator.

Details of any openings, holes, chases, etc. required to be formed or cutin the structure shall be approved by the Contract Administrator prior tothe work being carried out on site.

Immediately after striking the formwork, all surface fins and othersuperfluous projections shall be removed and purpose-made holes forinternal ties shall be made good with specially prepared cement mortarof equal quality as the concrete.


The Works Contractor shall as a minimum record the check onfollowing items:

Visual inspection of formwork design

Inspection of cleaning before concreting.

Visual inspection of watering of formwork where required.

4.5.3 Re-use of Formwork

Case should be taken, when re-using formwork, that its surface shall besmooth and clean and that it shall be free from warping, twisting or otherdeformation. Any formwork which has, in the opinion of theManagement Team, deteriorated sufficiently to render it unsuitable forthe work shall be rejected and must be removed from the siteimmediately or must be broken up at once, and new formwork beingprovided at the Works Contractors expense.


The Works Contractor shall as a minimum record the check onfollowing items:

Visual inspection of formwork before re-use.

4.5.4 Stripping of Formwork


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Formwork shall be removed in such a manner as not to cause anydamage to or over-stress in the concrete.

Formwork shall not be removed before the concrete has sufficiently setand hardened. The minimum periods which shall elapse betweenplacing the concrete and the removal of formwork for the various parts

of the structure shall be as given below.

These minimum requirements shall not relieve the Works Contractor ofthe obligation to delay the removal of forms if the concrete has notattained its specified working strength. Th

Civil specification.pdf

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