SPECIFICATION FOR CONCRETE CONSTRUCTION

SPECIFICATION FOR CONCRETE CONSTRUCTION

1.0 SCOPE

This specification covers the requirements for mixing, forming, reinforcing, placing, curing, testing, finishing and repairing of concrete structures and specifies the materials to be used and material storage and handling requirements.

2.0 CODES, REGULATIONS AND STANDARDS

2.1 General

CONTRACTOR shall meet or exceed the requirements of the latest edition of the following codes, regulations and standards, except as superseded herein. In cases where more than one code, regulation or standard apply to the same condition, the most stringent shall be followed. In the event of a conflict between this specification and other specifications or correspondence, the COMPANY shall be consulted and a ruling, in writing, shall be obtained before any work is started.

Some requirements in this specification may be modified by specific requirements in the project or purchase specifications. In case of conflict, the specific requirements supersede this specification.

Any deviation from this specification must be accepted, in writing, by COMPANY. Such written acceptance must be obtained prior to the commencement of any work which would constitute such a deviation.

2.2 International Standards

ACI 309, “Guide for Consolidation of Concrete”

ACI 318, “Building Code Requirements for Structural Concrete”

2.3 Indian Standards

IS: 73

IS: 2062

IS: 269

IS: 280

IS: 383

IS: 432

IS: 455

IS: 456

IS: 516

IS: 650

IS: 702

IS: 816

IS: 1199

IS: 1367

Specification for paving bitumen.

Specification for structural steel.

Specification for Ordinary Portland cement, 33 grades.

Specification of mild steel wire for general engineering purposes.

Specification for coarse and fine aggregates from natural sources for concrete.

Specification for mild steel and medium tensile steel (parts I & II) bars and hard drawn steel wire for concrete reinforcement.

Specification for Portland slag cement.

Code of practice for plain and reinforced concrete.

Method of test for strength of concrete.

Specification for standard sand for testing of cement.

Specification for industrial bitumen.

Code of practice for use of metal are welding for general construction in mild steel.

Method of measurement of building (part-II, and civil engineering works. V, VIII, XVIII).

Technical supply conditions for threaded steel fasteners.

IS: 1489

IS: 1566

IS: 1609

IS: 1786

IS: 1791

IS: 1838(Part I)

IS: 2204

IS: 2386

IS: 2438

IS: 2502

IS: 2505

IS: 2506

IS: 2514

IS: 2571

IS: 2645

IS: 2722

IS: 2750

IS: 2751

IS: 3025

IS: 3067

IS: 3150

IS: 3366

IS: 3370

IS: 3384

IS: 3414

IS: 3550

IS: 3558

IS: 3696

Specification for Portland-pozzolana cement. (Part-I – Fly ash based) (Part-II Claimed clay based).

Specification for Hard-drawn steel wire fabric for concrete reinforcement.

Code of practice for laying damp proof treatment using bitumen felts.

Specification for high strength deformed steel bars and wires for concrete reinforcement.

General requirements for batch type concrete mixers.

Specification for performed fillers for expansion joints in (concrete pavements and structures (none extruding and resilient type).

Code of practice for construction of reinforced concrete shell roof.

Methods of test of aggregates for concrete (Parts I to VIII).

Specification for roller mixer.

Code of practice for bending and fixing of bars for concrete reinforcement.

General requirements for concrete vibrators, immersion type.

General requirements for concrete vibrators, creed board type.

Specification for concrete vibrating tables.

Code of practice for laying in-situ cement-concrete flooring.

Specification for Integral cement water proofing compounds.

Specification for portable swing weight batchers for concrete. (Single and double bucket type).

Specification for steel scaffoldings.

Code of practice for welding of mild steel plain and deformed bars for reinforced concrete structures.

Methods of sampling and test waste water.

Code of practice for general design details and preparatory work for damp proofing & water proofing of buildings.

Specification for hexagonal wire netting for general purposes.

Specification for pan vibrators.

Code of practice for concrete structures for the storage of liquids. (Part I to IV).

Specification for bitumen primer for use in water proofing & damp proofing.

Code of practice for design and installation of joints in buildings.

Methods of test for routine control for water used in industry.

Code of practice for use of immersion vibrators for consolidating concrete.

Safety code for scaffolds and ladders (Part I & II).

IS: 4014

IS: 4031

IS: 4130

IS: 4326

IS: 4461

IS: 4656

IS: 4925

IS: 4990

IS: 4995

IS: 5121

IS: 5525

IS: 5624

IS: 6461

IS: 6494

IS: 6509

IS: 7193

IS: 7293

IS: 9103

IS: 9417

IS: 9595

IS: 10262

IS: 11384

IS: 12118

IS: 12200

IS: 12269 53

IS: 12600

SP: 23

SP: 24

Code of practice for steel tubular scaffolding (Parts I & II).

Methods for physical tests for hydraulic cement.

Safety code for demolition of buildings.

Code of practice for earthquake resistant design and construction of buildings.

Code of practice for joints in surface hydro-electric power stations.

Specification for form vibrators for concrete.

Specification for batching and mixing plant.

Specification for plywood for concrete shuttering work.

Criteria for design of reinforced concrete bins for the storage of granular and (Parts I & II) powdery materials.

Safety code for piling and other deep foundations.

Recommendations for details of reinforcement in reinforced concrete work.

Specification for foundation bolts.

Glossary of terms relating to cement concrete.

Code of practice for water proofing of underground water reservoirs and swimming pools.

Code of practice for installation of joints in concrete pavements.

Specification for glass fiber base coal-tar pitch and bitumen felts.

Safety code for working with construction machinery.

Specification for admixtures for concrete.

Recommendations for welding cold-worked steel bars for reinforced concrete construction.

Recommendations for metal-arc welding of carbon and carbon manganese steels.

Recommended guidelines for concrete mix design.

Code of practice for composite construction in structural steel and concrete.

Specification for two-part poly supplied.

Code of practice for provision of water stops at transverse contraction joints in masonry and concrete dams.

Grade ordinary Portland cement.

Portland cement, low heat.

Handbook of concrete mixes

Explanatory handbooks on IS: 456-1978

SP: 34 Handbook on concrete reinforcement and detailing.

2.4 Other

x National Building Code of India.

x International Building Code (IBC 2003)

x Codes, regulations and Statutes of Authorities having jurisdiction in the location of installation.

3.0 GENERAL

3.1 Definitions

COMPANY:

The COMPANY means Cairn Energy India Pty Limited, and its subsidiaries or authorized representative(s).

CONTRACTOR: Person(s), company, firm, manufacturers, fabricator or vender.

3.2 Workmanship

Work shall be carried out in accordance with code requirements and industry standards for good workmanship.

4.0 MATERIALS

4.1 General

4.1.1 All materials shall conform to IS 456 or ACI 318.

4.1.2 No material other than that specified shall be used unless accepted, in writing by COMPANY.

4.2 Storage of Materials

All material shall be stored in accordance with IS 4082.

4.3 Cement

4.3.1 Cement shall be Portland cement and comply with IS 269, IS 8112, IS 12269 or ACI 318, and shall be as shown on the drawings.

4.3.2 Types of Portland cement:

33 Grade Ordinary Portland Cement

43 Grade Ordinary Portland Cement

53 Grade Ordinary Portland Cement

Rapid Hardening Portland Cement

Sulphate Resistant Portland Cement

Low Heat Portland Cement

Type of cement shall be used as per Design brief.

4.4 Aggregates

4.4.1 Aggregates for concrete shall be in accordance with IS 383 or ACI 318.

4.4.2 The maximum size of the coarse aggregates shall be 20 mm unless otherwise noted on the drawings.

4.5 Admixtures

4.5.1 Air entraining admixtures shall be used in all concrete to be exposed to weathering and conform to IS 9103 or ACI 212.3R-04.

4.5.2 No other admixtures shall be used without COMPANY's written permission.

4.6 Water

Water used for mixing and curing shall be clean and free from injurious amount of oils, alkalis, salts, chlorides ions, organic materials or other substances that may be deleterious to concrete or steel and shall comply with IS 3025.

Potable water is generally considered satisfactory for mixing concrete. The pH value of water shall be more than 6. Mixing or curing of concrete with sea water is not recommended due to risk of corrosion of the reinforcement. Such corrosion is accelerated in warm and humid environments.

4.7 Steel Reinforcement

4.7.1 Reinforcing shall be new deformed steel bars or welded wire fabric, as specified on the drawings. Steel bars shall conform to IS 432 (Part 1), IS 1786 and Hard-drawn welded wire fabric to IS 1566 or ACI 318 Reinforcing bars shall be either Grade Fe 415 or Fe 500, unless specified otherwise.

4.7.2 Welding (including tack welding) of reinforcement bars is strictly prohibited unless noted.

All reinforcement shall be free from loose mill scales, loose rust and coats of paints, oil, mud or any other substances which may destroy or reduce bond.

All bars shall be bent cold. All bars bending schedules will show bar dimensions as out to out and will consider the bar length as the sum of all detailed dimensions.

Spacers cover blocks and chairs shall be used to maintain the specified nominal cover to the steel reinforcement. Spacers and cover blocks shall be of concrete of same strength or PVC. Chairs shall be a minimum of 8 mm reinforcing steel.

4.8 Steel Reinforcement Binding Wire

Black soft annealed steel binding wire, 16 SWG, shall be used for binding the reinforcing steel at every intersection.

4.9 Formwork for Concrete

4.9.1 Formwork materials shall be straight and free of warps and any defects which would produce blemishes in exposed concrete and shall conform to IS 14687.

4.9.2 Pre manufactured tube forms shall be of fiber paper, spiral wound and laminated.

4.10 Void Form

Void form shall be of compressible plastic fill materials capable of accommodating swelling of soils. It shall also have adequate strength to support the loading during concrete placement.

4.11 TIES

Internal form ties shall be metal, adjustable in length and of a type that no metal will remain within 35mm of the finished concrete surface. Toes shall have plastic cones at faces of concrete to facilitate patching.

4.12 Chamfer Strips

Chamfer strips shall be 20 to 25 mm, × 45°, cut from extruded PVC or sawn lumber.

4.13 Backfill

4.12.1 Structural fill shall be comprised of clean, well-graded inorganic granular soils.

4.12.2 General engineered fill shall be comprised of clean, well-graded granular soils or inorganic low-plastic cohesive soils.

4.14 Vapour Barrier

Vapor barrier shall be polyethylene sheeting.

4.15 Mastic

Mastic shall be plastic cement, cutback asphalt.

4.16 Anchor bolts

Anchor bolt material shall confirm to IS 1363.

5.0 CONCRETE QUALITY

5.1 Mix Design –

5.1.1 The design of all concrete mixes shall be by an approved and certified laboratory in the employ of CONTRACTOR.

5.1.2 The 28 day compressive strength of concrete shall be as specified on the drawings. Lean-mix concrete (plain cement concrete) strength shall be 15 MPa. Minimum reinforced concrete strength shall be 30 MPa for structural elements.

5.1.3 For pavements and heavy mass construction, the maximum allowable slump shall not exceed 75 mm. The slump shall not exceed 100 mm for all other concrete unless noted on the drawings.

5.1.4 Air entraining admixtures shall be used in all concrete to be exposed to weathering and shall have 3 to 6 percent entrained air by volume. Concrete for floor slabs whose edges are exposed to weathering shall have 3 to 5 percent entrained air by volume to facilitate the application of a floor hardener and sealer as specified on the drawings.

5.1.5 Mix designs shall be supplied to COMPANY by CONTRACTOR for acceptance before any concrete is placed.

5.2 Proporting of Concrete Mix

Proportioning of the concrete mix shall be based on the standard deviation computed from compressive strength tests of previous batch records or established by laboratory mix trial.

For a design mix based on the standards deviation computed from compressive strengths of previous batch, the previous batches shall represents similar material and conditions.

In meeting strength requirements, the selected job mix proportions shall provide an average strength FCR, exceeding the compressive strength FC.

5.3 Sampling, Testing and Quality Assurance

5.3.1 Facilities required for sampling materials, concrete, reinforcement, formwork, etc. in the field and in the laboratory shall be provided by the Contractor. The Contractor shall carry out all sampling and testing in accordance with the relevant India standards and/or International standards and this specification. Where no specific testing procedure is mentioned, the tests shall be carried out as per the prevalent accepted engineering practice to the directions of the Engineer. Tests shall be done in the field in the presence of the Engineer or his authorized representative and at a laboratory company representative approved by the company representative, and the contractor shall submit to the company representative the test results in triplicate within three days after completion of any test.

5.3.2 The contractor shall maintain records of all inspection and testing, which shall be made available to the company representative. The Engineer at his discretion may waive some of the stipulations for small unimportant concreting operations and other works.

5.3.3 Work found unsuitable for acceptance shall be removed and replaced by the Contractor. The work shall be redone as per specification requirements and to the satisfaction of the Engineer at no extra cost to the company.

5.3.4 Quality Assurance Programme

a) The Contractor shall submit and finalize a detailed field Quality Assurance Programme within 30 days from the date of award of the contract, before commencement of work at site, according to the requirements of the specification. This shall include setting up of a testing laboratory, arrangement of testing apparatus/equipment, deployment of qualified/experienced manpower, preparation of format for record, field quality plan etc. On finalized field quality plan, the Owner shall identify, customer hold points, beyond which work shall not proceed without written approval from the company representative. The testing apparatus/equipment installed in the field laboratory shall be calibrated /corrected by the authorized persons as frequently as possible to give accurate testing results.

b) Frequency of sampling and testing, etc. and Assurance Criteria are given in respective sections. However, the testing frequencies set forth are the desirable minimum and the company representative shall have the full authority to carry out or call for tests as

frequently as he may deem necessary to satisfy himself that the materials and works comply with the appropriate specifications.

5.4 Failure to meet specification

5.4.1 Batches of concrete not meeting either the slump or air entrainment requirements shall be rejected.

5.4.2 Concrete in place that has not met the requirements of this specification shall be removed and replaced or repaired as required by COMPANY. Failure to meet specification includes, but is not limited to, the following:

x Low strength or low durability concrete as evaluated by test results.

x Reinforcement steel size, quantity, strength, position or arrangement not in accordance with drawings or this specification.

x Concrete that differs from the required dimensions or location in such a manner so as to reduce its strength or stability.

x Curing less than specified.

x All costs involved in such work shall be borne by CONTRACTOR.

6.0 PREPARATION FOR PLACING

6.1 Excavation

6.1.1 The excavation shall be of sufficient size to allow for dewatering and formwork and proper working space as per the Indian standards. Adequate measures shall be taken to prevent slips, cave-ins and slides.

6.1.2 Footing excavations shall be carried down to the designated bearing strata as shown on the drawings.

6.1.3 All foundation excavations and bearing surfaces shall be inspected by a qualified geotechnical engineer as required by COMPANY.

6.1.4 Where unsuitable material is encountered, the unsuitable material shall be over excavated to reach the desired bearing stratum and backfilled with structural fill compacted in accordance with site specific soil report or, alternatively filled with lean-mix concrete.

6.1.5 If excavations are carried out below the indicated or specified elevations due to negligence on the part of the CONTRACTOR, then the over excavation shall be refilled to the required elevation with lean mix concrete at the CONTRACTOR’s expense.

6.1.6 Excavated area shall be kept free from loose material, debris and water.

6.1.7 All excavations and bearing surfaces shall be protected against rain, freezing temperatures and the ingress of water at all times during foundation construction.

6.1.8 If the bearing surface is to be left exposed for more than 24 hours, a 75 mm thick mat of lean-mix concrete shall be placed on the bearing surface.

6.1.9 Vapor barrier shall be placed as shown on the drawings. Vapor barrier shall be lapped 150 mm at joints and shall be sealed with mastic. Punctures in vapor barrier shall be sealed with a patch 150 mm larger than puncture and sealed with mastic.

6.2 Formwork

6.2.1 Formwork shall conform to Indian Standard IS 14687.

6.2.2 Forms shall be rigidly constructed and sufficiently tight to prevent leakage.

6.2.3 Panels forming the formwork shall not be dented, deformed or distorted from handling or overuse.

6.2.4 Forms shall be suitable for the particular work. The faces of forms for exposed concrete surfaces shall be selected to provide a smooth surface. Any form surface that comes in contact with concrete shall have mould oil coating, or approved equal.

6.2.5 Forms shall be constructed and assembled to facilitate their removal without damage to the concrete.

6.2.6 Forms shall be left in place for 7 days or as specified in IS 456 or ACI 318 unless directed otherwise by COMPANY. In no case, shall supporting forms or shoring be removed until members have acquired 60% of the specified strength to support their weight and imposed loads safely.

6.2.7 Stability and tightness (at joints) of framework must be maintained during vibration.

6.2.8 Formwork may be constructed from wood, metal, or any other elements which assures similar conditions of efficiency.

6.3 Placing Reinforcement

6.3.1 Placement of reinforcement shall conform to the applicable codes, specifications and recommended practices listed in Section 2.1.

6.3.2 Reinforcement shall be accurately placed in accordance with the drawings. Tolerances on placement of reinforcement shall conform to IS 456 or ACI 318 (±10mm for effective depth 200mm or less; ± 15mm for effective depth greater than 200mm).

6.3.3 The ends of the black annealed steel wire used for binding the reinforcing material shall not encroach into the concrete cover and shall be tucked-in to prevent corrosion spots in the concrete.

6.3.4 Minimum concrete clear cover of reinforcement shall be as specified on the drawings.

6.3.5 No splices of reinforcement shall be made except as shown. Splices on welded wire fabric shall be made by overlapping two mesh panels.

6.3.6 Exposed reinforcing bars intended for bonding with future extensions shall be protected from corrosion by concrete or other adequate covering.

6.3.7 Welding of reinforcement shall not be allowed without the written acceptance of COMPANY

6.3.8 Wherever conduit, piping, insets, sleeves, etc. as shown on the drawings interface with the placing of reinforcement, proper adjustment shall be made as directed by COMPANY.

6.4 Joints

6.4.1 Construction, control and expansion/isolation joints shall be made in accordance with IS 516 or ACI 318

6.4.2 Construction joints not indicated on the drawings shall be made only with COMPANY's acceptance.

6.4.3 Where a construction joint is indicated on the drawings, a delay until the concrete is no longer plastic in columns or walls must occur before concrete is placed in the beams, girders, or slabs to be supported.

6.4.4 Saw cuts for control joints shall be made within 12 hours after concrete is poured.

6.5 Water Stop

Water spots shall be firmly held in correct position as the concrete is placed. Joints in rubber or plastic water stops shall be cemented, welded or vulcanized as recommended by the manufacturer. Joints shall be watertight. Inspection water stops shall be prefabricated and supplied by the same manufacturer,

6.6 Anchor Bolts and Other Embedded Items

Fabrication of anchor bolts and miscellaneous hardware shall be as shown on the drawing and in accordance with applicable codes, specifications and recommended practices listed in section 2 of this specification.

Above all elements shall be held firmly in place through the use of jigs and other approves techniques that avoid movement during the pouring of concrete. All such elements shall be degreased and meticulously cleaned before concrete is poured and expose part shall be properly protected to avoid contact from the poured concrete.

6.7 Inspection

A thorough inspection of the forms, reinforcement and all embedded items shall be made by COMPANY before proceeding with the placing of concrete as follow:

a) Reinforcement of correct size and spacing is securely and properly fastened in its correct position.

b) All forms are correctly located. Structural strength and stability of forms is Contractor’s responsibility.

c) All embedded items are securely anchored and correctly coated.

d) All forms and reinforcement are clean and wetted as required and excess water and debris has been removed form inside the forms.

e) Prior to placing concrete, al requirements relating to concrete testing, placement, and finishing as well preparation for cold or hot weather concreting shall have been met and approved by COMPANY.

7.0 PRODUCTION, DELIVERY AND PLACEMENT

7.1 Production

7.1.1 Production of concrete shall be in accordance with IS 456 or ACI 318.

7.1.2 Ready-mixed concrete is preferred for jobs where concrete can be placed within the initial setting time after first mixing of the water, cement and aggregate.

7.1.3 Concrete shall be mixed only in batch quantities that can be promptly disposed of in the work. Concrete shall not be used after it has acquired an initial set.

7.1.4 If a site batch plant is used, COMPANY may require preliminary test batches to ensure concrete quality.

7.1.5 Small quantities of concrete may be site-mixed, providing that COMPANY's acceptance of equipment and procedures to be used is first obtained.

7.2 Delivery

7.2.1 Concrete will be conveyed and handled in accordance with IS 456 or ACI 318.

7.2.2 Concrete must be delivered and discharged from the truck mixer or agitator truck within the initial setting time after introduction of the water to the cement and aggregate or the cement to the aggregate, unless otherwise accepted by COMPANY.

7.2.3 Retempering is not permitted. Retempering is defined as the addition of water to restore slump lost during excessive mixing due to excessive lapse of time since initial mixing.

7.2.4 Equipment for conveying concrete, such as buckets, trucks, belt conveyors, pumps, etc., shall be of such design, size and condition to ensure a continuous and adequate supply of concrete of the specified mix and slump, without segregation at the point of deposition.

7.3 Placement

7.3.1 A thorough inspection of the forms, reinforcement and all embedded items shall be made by COMPANY before proceeding with the placing of concrete as follows:

Reinforcement of correct size and spacing is securely and properly fastened in its correct position.

All forms are correctly located. Structural strength and stability of forms is CONTRACTOR’s responsibility.

All embedded items are securely anchored and correctly coated.

All forms and reinforcement are clean and wetted as required, excess water and debris has been removed from inside the forms.

Inspection by COMPANY does not in any manner relieve CONTRACTOR of his responsibility.

7.3.2 Prior to placing concrete, all requirements relating to concrete testing, placement, and finishing as well as preparation for cold or hot weather concreting shall have been met and approved by COMPANY.

7.3.3 Before placement, all equipment for delivery and placing shall be cleaned and all debris, loose or unsound material, water and ice removed from areas to be concreted.

7.3.4 Concrete shall not be placed against frozen ground or subgrade, or against soil which has been subject to excessive water or drying.

7.3.5 The minimum temperature of concrete during placing shall be 10° C. During hot weather, proper attention shall be given to ingredients, production methods, handling, placing, protection, and curing to prevent excessive concrete temperatures or water evaporation that could impair required strength or serviceability of the member or structure. Recommendations shall conform with IS 7861.

7.3.6 Concrete placement will be such as to prevent water from collecting at the ends and corners of the forms and along form faces.

7.3.7 Concrete shall not be poured during rain unless adequately protected.

7.3.8 Surface vibrators shall be used. Concrete shall be thoroughly compacted or vibrated. All concrete shall be compacted by internal vibration using mechanical vibrating equipment, except that concrete in floor slabs, sidewalks, or curb and gutter, not poured against form linings, shall be either tempered or vibrated. Care must be taken in vibrating the concrete to vibrate only long enough to bring a continuous film of mortar to the surface. Vibration shall stop before any segregation of the concrete occurs. Mechanical vibrators shall be an approved type as specified in ACI 309, Chapter 5, IS 2505 or IS 2506. Vibrators shall not be used to spread the concrete.

7.3.9 Install all embedded items such as anchor bolts, sleeves, inserts, equipment bed and slide plates in their correct locations and secure against displacement.

7.3.10 Concrete shall not be dropped vertically more than 2.5 m; drop chutes shall be used for higher lifts. The chute shall have a diameter of at least eight times the maximum aggregate size and shall be positioned so that the concrete will drop vertically

7.3.11 In case of placement of ready mix concrete a spare concrete pump shall be made available at all the time when concreting is in progress.

7.3.12 Ready-mixed concrete is preferred for jobs where concrete can be placed within one and one half hours after first mixing of the water, cement and aggregate.

Concrete shall be uniform and thoroughly mixed when delivered to the forms in a freshly mixed and unhardened state.

No mixing of water in excess of the amount specified for the mix shall be added to the concreting during mixing or hauling or after the arrival at the delivery point.

Concrete may be furnished by ready-mix methods, by volumetric batching and continuous mixing at site, or by batch mixing at site.

a) Ready Mixed Concrete

Ready mixed concrete shall be mixed, transported and placed in a freshly mixed and unhardened state. The contractor shall furnish the COMPANY batch record showing the amount of concrete in cubic yards, the time of loading, the time load was discharged, and the type and quantity of each material including all admixtures used in each batch of concrete.

b) Volumetric batching and continuous mixing at site

Volumetric batching and mixing is normally done at site. The batch and mixing equipment shall conform to the requirements of ASTM C 685. Concrete made by this method is produced, inspected and documented in conformance with sections 6, 7,8,13 and 14 of ASTM C 685.

c) Batch Mixing at site

This method of batching and mixing is done on site using paving mixers or stationary construction mixers or by using a combination of centrally batching part of the mix and transporting it to the site, and adding rest of the material on site.

7.4 Preparation of Forms and Subgrade -

Before placement of concrete, the forma and subgrade shall be free of chips, sawdust, debris, water, ice snow, extraneous oil, mortar or other harmful substances required to be bonded to the concrete shall be removed.

Weep holes in walls or slabs shall be formed with nonferrous metal.

7.5 Removal of Forms, Supports and Protective Coatings

Forms, supports and protective coatings shall be removed as practical after the concrete has gained sufficient strength to support its own weight and superimposed loads. Removal shall be done so that the concrete is not damaged and sudden or excessive stresses are not included.

The accumulated form removal times shall be as per the codes and specifications outlined in section 4 and this specification.

8.0 CURING AND PROTECTION

8.1 Curing

8.1.1 Curing of concrete shall conform to IS 456 or ACI 318. Particular attention shall be paid to cold and hot weather curing.

8.1.2 During the curing period only such areas as are needed for immediate surface finish treatment shall be uncovered. After finish treatment, such areas shall be immediately re-covered and the curing continued.

8.1.3 When the ambient temperature falls below 5° C, a complete record of the temperature and the protection given to the concrete while curing shall be kept. The number of points at which temperature records are kept shall be accepted by COMPANY.

8.1.4 Sealing curing compounds shall not be used unless specifically accepted by COMPANY. They shall not be used on vertical concrete surfaces which will be exposed on completion of the job.

8.2 Protection

8.2.1 Protection of concrete shall conform to IS 456 or ACI 318.

8.2.2 Freshly placed concrete shall be protected against traffic, direct sunshine, drying winds, excessive heat, and cold and rain water.

8.2.3 If grouting of equipment or base plates is not to be completed immediately as directed by COMPANY and when the ambient air temperature is less than 5°C, plastic anchor bolt sleeves shall be filled with antifreeze.

9.0 REPAIR AND FINISHING

9.1 Repair

9.1.1 Repair of concrete shall conform to IS 456 or ACI 318.

9.1.2 Repair of voids, honeycombs, sand pockets, excessive finning, and other similar gross imperfections, shall be completed within 24 hours after removal of forms. Curing procedures shall not be delayed or interrupted while making such repairs.

9.1.3 Dry-packed mortar, consisting of 1 part Portland cement and 2-1/2 parts of sand (100 percent shall pass No. 16 sieve), shall be used to fill cleaned out voids nominally not exceeding 150 mm in depth or 0.03 cubic meters in volume. Concrete of the same mix characteristics as the concrete to be repaired shall be used to fill larger voids, where a sounder patch can be achieved than by the use of dry-pack mortar.

9.1.4 Mortar used in patching shall not be more than one hour old. The mortar patches shall be cured in accordance with this specification. All construction and expansion joints in the completed work shall be left carefully tooled and free of all mortar and concrete. The joint filler shall be left

exposed for its full length with clean and true edges. uniform.

9.2 Finishing -

The resulting surfaces shall be true and

9.2.1 Finishing shall conform to IS 456 or ACI 318.

9.2.2 The surfaces of concrete which are to be grouted shall be left rough and unfinished to ensure a good bond between concrete and grout.

9.2.3 A smooth-rubbed finish shall be used on the faces of all exposed concrete unless otherwise specified.

9.2.4 After the final rubbing is completed and the surface has dried, it shall be rubbed with burlap to remove loose powder and shall be left free from all unsound patches, paste, powder and objectionable marks.

9.2.5 Sidewalks and pads shall be given a broom finish.

9.2.6 Floors shall be given a smooth steel trowel finish.

9.2.7 If shown on the drawings, a colored non-metallic concrete hardener and sealer shall be applied to the floor slabs in strict accordance with the manufacturer's instructions. The finished floor slab shall be in the color shown on the drawings.

9.3 Concrete in Hot Weather

Concreting in hot weather is performed when high ambient temperatures, high concrete temperature, low relative humidly etc., are observed.

The contraction shall maintain the temperature of concrete below 90 degrees Fahrenheit

During mixing and conveying

Exposed concrete surfaces that tend to dry or set rapidly will be continuously moistened.

Using for sprays or any other methods to maintain adequate moisture during the time between placing and finishing of concrete. Water shall not be directly added to the surface of concreting before finishing.

9.4 Concrete Tolerances

The dimension of formed members, unless otherwise specified will be satisfactory if they conform to the requirement of specifications, the location shown on the drawings, and are within the acceptable tolerances as specified in the codes.

10.0 BACKFILL

Backfill around foundations shall be placed in such a manner as to minimize settlement and to provide a relatively impervious layer to minimize seepage into the subsoil and so graded that water does not pond at or close to the foundation.

Backfill shall be general engineered fill and free from organic material, wood scraps, paper or other undesirable material,

Backfill shall not be placed against a concrete foundation until the structure has gained sufficient strength to withstand the earth pressures resulting from placement and compaction.

Backfill around foundations shall be carefully and uniformly compacted in 150 mm compacted lifts to 95 percent Standard Proctor maximum dry density at or near optimum moisture content and shall consist of clean material with all lumps broken down or squeezed together during compaction.

Only hand held compaction equipment shall be used in the compaction of fill within 500 mm of retaining walls.

11.0 CLEAN-UP AND RESTORATION

Upon completion of the work, contractor shall clean up and remove all loose material and debris from the job site, and dispose of it as waste material as directed by Company.

Before leaving the job site, Contractor shall ensure that all existing structures, roadways and graded areas are returned to a condition satisfactory to COMPANY and at least equal to that which existed before the work commenced.

12.0 INSPECTION

12.1 CONTRACTOR shall provide access to the work at all times to COMPANY for checking materials, and fabrication and installation procedures.

12.2 Inspection by COMPANY does not in any manner relive CONTRACTOR of his responsibility.

12.3 COMPANY shall have the right to stop work and require repairs or alternation if, in his opinion, the materials or workmanship do not meet the required specification.

12.4 Any omissions or failure on the part of the COMPANY to disapprove or reject any work or materials must not be construed as an acceptance any defective work or materials.