CONCRETE.PDF

05-26-10 03301 - 1 Concrete, Formwork, and Reinforcement

SECTION 03301

CONCRETE, FORMWORK, AND REINFORCEMENT

PART 1 GENERAL

1.01 SCOPE

A. Applies to cast- in-place concrete, formwork, and steel reinforcement.

PART 2 PRODUCTS

2.01 FORMS

A. Plywood, hardboard, wood, metal, or other approved material to yield the required finish. Free of bulge, warp, or other defects, which would cause blemishes. Forms shall be thoroughly clean.

2.02 STEEL BAR REINFORCEMENT

A. Deformed bars of intermediate grade with minimum yield stress of 40,000 pounds per square inch (psi), conforming to AASHTO M-31, M-42; or M-53; or ASTM A-615, A-616; or A-617, respectively.

2.03 WELDED WIRE FABRIC

A. AASHTO M-32 and M-55 or ASTM A-82 and A-185.

2.04 PORTLAND CEMENT

A. AASHTO M-85 or ASTM C-150, type I.

2.05 AGGREGATES

A. Maximum size 1" for reinforced work and 1-1/2" for non-reinforced. AASHTO

M-6 and M-80, or ASTM C-33.

2.06 WATER

A. Clean, fresh, and free from injurious amounts of mineral and organic substances.

2.07 ADMIXTURES

A. Air-entraining admixtures shall conform to ASTM C-260 (AASHTO M-154).

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B. When approved for use, water-reducing admixtures, retarding admixtures, and accelerating admixtures shall conform to ASTM C-494 (AASHTO M-194).

2.08 CONCRETE MIX DESIGN

A. Proportion and mix to obtain concrete of 4,000 psi minimum compressive strength at 28 days. Water/cement ratio shall not exceed 0.46 by weight, including free surface moisture on the aggregates and liquid admixtures. Slump shall not exceed 4" or be less than 1".

B. Add air-entraining admixtures to the concrete mix in an amount to produce for

1" aggregate 6 percent + 1 percent, for 1-1/2" aggregate 5 percent + 1 percent air by volume.

C. Use of other admixtures not permitted unless written approval is obtained from the CO.

2.09 CURING COMPOUNDS

A. Liquid membrane-forming compounds suitable for application on horizontal and vertical concrete surfaces complying with ASTM C-309-74, type I.

2.10 BONDING AGENTS

A. High strength, moisture insensitive, dry or damp cure, epoxy adhesive, Sikadur

Hi-Mod as manufactured by Sika Chemical Corp., P.O. Box 297, Lyndhurst, NJ 07071, (201) 933-8801, or approved equal.

2.11 ANCHOR BOLTS

A. Size and type as shown on the drawings and complying with ASTM A-307.

2.12 GROUT

A. Nonshrink Grout: In the liquid state, grout shall show no shrinkage in accordance with ASTM 827-78, and in the hardened state under ASTM C-157-

77. The effective bearing area (EBA) shall be not less than 95 percent. The grout shall have a time of initial set of not less than 60 minutes under ASTM C- 191-74. Perform all grouting in accordance with the manufacturer's published specifications for mixing and placing. All nonshrink grout shall be Five Star Grout as manufactured by U.S. Grout Corp., Old Greenwich, CT 06870, (203) 637-4303, or approved equal.

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2.13 FORM TIES

A. Steel with metal or plastic cone form spreaders, 3/4" minimum back break.

2.14 WATERSTOPS

A. Polyvinyl chloride material; ribbed-centerbulb (expansion joints), flat-ribbed

(construction joints), or split-ribbed (expansion/ construction joints), as manufactured by the Vinylex Corp., 2636 Byington-Solway Road, Knoxville, TN 37921, (615) 690-2211, or approved equal.

PART 3 EXECUTION

3.01 FORMWORK

A. Form to shapes, lines, and dimensions shown on the drawings. Brace or tie forms tightly together to maintain position and shape, and to prevent leakage of mortar.

B. Do not remove forms until the concrete has hardened sufficiently to resist damage from removal operations. Construction loads shall not be placed upon, or any forms removed from, the concrete until it has attained sufficient strength to safely support its weight and construction loads.

C. Prior to placing the reinforcing steel, place moisture barrier, if required; clean and seal forms with form oil, form sealer, or an approved non-absorptive liner.

3.02 REINFORCEMENT

A. Bending: Reinforcement shall be bent cold. Do no bend reinforcement partially embedded in concrete. Bend bars and fabric in accord with ACI 318, Chapter 7.

B. Surface Conditions: Reinforcement shall be free from dirt, oil, paint, grease, loose mill scale, and loose or thick rust when placed.

C. Tie all bar-to-bar crossings with wire.

D. Splice welded wire fabric by lapping one grid plus 2" each side.

E. Splice steel bar reinforcement with an overlap of not less than 18".

F. Extend reinforcement through contraction and construction joints.

Reinforcement shall not be extended through keyed joints. Expansion joints shall be reinforced as shown on the drawings, when applicable.

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3.03 PREPARATION FOR PLACING

A. Before placing concrete, complete the formwork; place moisture barrier and expansion joint filler, if required; secure reinforcement; install anchors and other embedded items; and, obtain approval of the entire preparation from the CO.

B. Anchors for fastening equipment and materials to concrete shall be as shown on the drawings.

C. Anchors and accessories that are required to be cast with the concrete shall be set and maintained in their required positions.

D. Anchors and accessories that are set in concrete after the concrete has set shall be located as shown on the drawings or at such location as to prevent spalling or other damage to the concrete.

E. Finish elevation of anchors shall ensure at least 1-1/2 full threads above the nut when the appropriate accessory is bolted to the anchor.

3.04 PLACING

A. Notify the CO 24 hours in advance of any concrete placing. Do not place concrete except in the presence of the CO. Temperature of fresh concrete at placement shall be between 55º and 80º F.

B. Place only upon clean, damp surfaces free from debris, frost, ice, and water, and never upon mud or dried, porous earth.

C. Consolidate by thoroughly working around reinforcement and embedded items, and into corners of forms, eliminating all air or stone pockets. Method of consolidation shall be approved by the CO.

1. Stop consolidation before any segregation of concrete occurs.

2. Where a surface mortar is to be the basis of the finish, work the coarse aggregate back from the forms to bring a full surface of mortar against the forms without the formation of voids.

3.05 CONCRETE WORK IN COLD WEATHER

A. During cold weather, maintain temperatures of concrete at 70º F for 3 days, or

50º F for 5 days. Do not allow concrete to freeze during the next 4 days.

B. Frozen concrete shall be removed at the Contractor's expense.

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3.06 CONCRETE FINISHING

A. After the concrete has been placed and consolidated, surplus concrete on unformed surfaces shall be struck smooth.

B. Vertical formed surfaces shall be ordinary finish, which is defined as the finish left on the surface after removal of forms, filling all holes left by form ties, and repairing all defects. The surface of ordinary finish shall be true and even, free from stone pockets and depressions or projections.

C. Interior slabs shall be steel trowel finished. Pitch to door or floor drains as indicated on the drawings. Exterior slabs shall be rough broom finished with tooled edges and weak plane joints.

3.07 BAR SUPPORTS

A. Support reinforcing bars and welded wire fabric to prevent displacement by construction loads or placing of concrete.

B. On-the-ground, and when necessary, approved bar supports with sandplates shall be used.

C. Over formwork, approved bar chairs and spacers shall be used.

3.08 CURING AND PROTECTION

A. Regardless of temperature, weather, or season, protect all concrete from premature drying and damage for a period of not less than 7 consecutive days.

Curing may be accomplished by saturating with clean water, or with an approved curing compound, of the surface membrane type, as approved by the

CO.

3.09 GROUTING

A. All voids and honeycombs shall be grouted with cement mortar. All surfaces to receive grout shall be clean and sound. The surface may be dry, damp, or wet, but free of standing water.

B. Prior to placing grout, apply bonding agent to the surface receiving the grout according to the manufacturer's recommendations.

END OF SECTION