SECTION 0320 REINFORCING STEEL

Transcription

1 SECTION 0320 REINFORCING STEEL PART GENERAL 1.01 SCOPE OF WORK: A. The Contractor shall furnish all necessary labor, materials, equipment and services to complete reinforcing steel work and related items as indicated on the drawings or specified herein including, but not necessarily limited to the following: 1. Reinforcing steel bars. 2. Welded wire fabric. 3. Accessories for reinforcing steel including reinforcing bar supports and tie wire. 4. Steel dowels at joints. B. RELATED WORK SPECIFIED ELSEWHERE: 1. Reinforcing for Concrete Drainage Structures - Section Reinforcing for Exterior Concrete Paving, etc. - Section Cast-in-Place Concrete Work - Section APPLICABLE CODES AND STANDARDS: A. CODES: All work specified under this Section shall comply with the following codes: 1. North Carolina State Building Codes. 2. "Building Code Requirements for Reinforced Concrete" ACI-318. B. STANDARDS: All work specified under this Section shall comply with all applicable requirements of the following standard specifications. In the event of conflict between the standard specifications and the project specifications, the project specifications shall govern. 1. Standard specifications of The American Society for Testing and Materials (ASTM) as follows: A82 - Standard Specifications for Cold-Drawn Steel Wire for Concrete Reinforcement. A184 - Standard Specifications for Fabricated Steel Bar or Rod Mats for Concrete Reinforcement

2 A185 - Standard Specifications for Welded Steel Wire Fabric for Concrete Reinforcement. A615 - Standard Specification for Deformed Billet Steel Bars for Concrete Reinforcement. 2. Standard specifications of the American Concrete Institute (ACI) as follows: Buildings. ACI Specifications for Structural Concrete for ACI Details and Detailing of Concrete Reinforcement. ACI 315R - Manual of Engineering and Placing Drawings for Reinforced Concrete Structures. 3. Recommended practices of the American Welding Society (AWS) as follows: AWS D "Recommended Practices for Welding Reinforcing Steel, Metal Inserts and Connections in Reinforced Concrete Construction" SUBMITTALS: 4. Recommended practice of the Concrete Reinforcing Steel Institute (CRSI) as follows: "CRSI Recommended Practice for Placing Reinforcing Bars". A. SHOP DRAWINGS: Shop drawings shall be prepared and submitted for reinforcing in all concrete work except concrete slabs on grade and elevated concrete slabs with fabric reinforcement only. Shop drawings shall fully indicate reinforcing size, spacing, splices, dimensions and placement details. Nomenclature on shop drawing sections and details shall correspond to project drawings. A complete list of materials shall accompany shop drawings. Each item on the list of materials shall indicate number of pieces, size, length, mark type, dimensions, etc. Shop drawings shall indicate bar support types and locations. Details of concrete reinforcement and accessories shall be in accordance with ACI 315 and ACI315R. Submit shop drawings in accordance with the requirements of Section B. MILL TEST REPORTS: Mill test reports for reinforcing steel shall be submitted to the Engineer upon request

3 1.04 PRODUCT HANDLING: A. PROTECTION: 1. All necessary means shall be used to protect materials specified under this Section from damage before, during and after installation. 2. The work of other trades shall be adequately protected from damage resulting from work specified under this Section. B. STORAGE AND HANDLING OF MATERIALS: 1. All reinforcing steel materials shall be stored a minimum of six (6) inches above the ground on wood pallets or the equivalent. Materials shall be adequately protected from mud, dust and dirt. C. PACKAGING AND MARKING: Each different type and configuration of reinforcing bars shall be tied into a separate bundle with wire. Each bundle shall be identified with an embossed metal tag that corresponds with the mark numbers on the reinforcing steel shop drawings ACCEPTANCE AND TOLERANCES: A. ACCEPTANCE: Acceptance of the reinforcing steel installation will depend upon compliance with this Section of the specifications. Lack of compliance will be treated in accordance with Chapter 18 of ACI 301. B. FABRICATION TOLERANCES: Reinforcing bars shall be fabricated to meet the following tolerances: 1. Sheared length: Plus or minus one (1) inch. 2. Depth of truss bars: Plus 0 inch, minus 1/2 inch. 3. Overall dimensions of stirrups, ties and spirals: Plus or minus 1/2 inch. 4. All other bends: Plus or minus one (1) inch. C. PLACEMENT TOLERANCES: Reinforcing shall be placed to meet the following tolerances: 1. Clear distance to formed surfaces: Plus or minus 1/4 inch. 2. Minimum spacing between bars: Minus 1/4 inch. 3. Top bars in slabs. a. Members eight (8) inches deep or less: Plus or minus 1/4 inch. 4. Crosswise of members: Spaced evenly within two (2) inches. 5. Lengthwise of members: Plus or minus two (2) inches

4 PART PRODUCTS 2.01 MATERIALS: A. REINFORCING STEEL shall be deformed steel bars with a minimum yield strength, fy, of 60,000 psi conforming to the requirements of ASTM A615, Grade 60. B. WELDED WIRE FABRIC shall be fabricated from plain cold drawn wire of gauge and mesh size indicated on the drawings. Welded wire fabric shall conform to the requirements of ASTM A185. Welded wire fabric heavier than six gauge shall be fabricated and delivered in flat sheets. Welded wire fabric six gauge and lighter may be fabricated and delivered in rolls or flat sheets. C. BAR SUPPORTS AND ACCESSORIES: 1. Formed Concrete Work: Bar supports and accessories shall be of suitable type and configuration as manufactured by Richmond Screw Anchor Company or approved equal. Bar supports and accessories in concrete surfaces exposed to weather, high humidity or corrosive atmosphere shall be hot dip galvanized in accordance with ASTM A153, Class D and plastic coated in accordance with ACI 315 and ACI 315R. 2. Concrete Foundation Mats: Bar supports for foundation mats shall be four (4) inches by four (4) inches by three (3) inches high precast concrete bricks. At the Contractor's option, type HC high chairs with sand plates may be used in lieu of precast concrete bricks. Bar supports between layers of foundation mats shall be Standees fabricated from No. 4 reinforcing bars. 3. Concrete Slabs on Grade: Bar supports for reinforcing steel shall be four (4) inches by four (4) inches precast concrete bricks. Height of brick shall be as required to locate steel at mid-depth of slab unless otherwise indicated on the drawings. Bar supports between layers of reinforcing steel shall be Standees fabricated from No. 4 reinforcing bars or type SBU slab bolsters. Welded wire fabric shall be supported on continuous type SB slab bolster with sand plates. If the Contractor can institute and enforce a method satisfactory to the Engineer for lifting and holding welded wire fabric into proper position during placing operations, the requirement for continuous slab bolsters will be waived. 4. Steel Dowels: Steel dowels at joints shall be 3/4 inch diameter by 16 inches long smooth steel rods conforming to ASTM A36. Ends shall be saw cut

5 PART EXECUTION 3.01 EXAMINATION AND PREPARATION OF SURFACES: A. FORM COATING: Reinforcing steel shall not be placed until after forms have been coated as specified in Section B. PREPARATION OF EXCAVATIONS: Reinforcing steel shall not be placed in footing excavations until excavations have been properly graded, shaped and prepared as specified in Section 0210 and Section Reinforcing steel shall be removed from excavations that have been caved in or have been damaged by adverse weather until such time as excavations have been cleaned out and reshaped INSTALLATION AND WORKMANSHIP: A. PLACEMENT OF REINFORCING: 1. Supports and Anchorage: a. Bars: All reinforcing steel bars shall be supported and anchored in place in such a manner as to insure final placement in accordance with specified tolerances. Spacing of supports shall conform to the requirements of ASTM A315. Continuous slab bolsters shall be used as required to position reinforcing off vertical form surfaces to within specified tolerances. Spacing of precast concrete bricks shall in no case exceed the following: No. 3 and No. 4 bars: 4'-0" on center No. 5, No. 6 and No. 7 bars: 6'-0" on center b. Welded Wire Fabric: Welded wire fabric shall be adequately supported during placing of concrete to insure its proper position in the slab. Welded wire fabric shall preferably be placed at the upper one third point of the slab depth. Welded wire fabric placed in the middle one third of the slab depth will, however, be acceptable. Fabric shall extend across supporting elements to within two (2) inches of concrete edges. 2. Wire Ties: Wire ties shall be used at intersections of reinforcing steel as required to insure final placement in accordance with specified tolerances but not more than 24 inches on center. All lapped splices shall be secured with a minimum of two (2) wire ties per lap. Side laps and end laps in welded wire fabric shall be anchored with wire ties at intervals not exceeding 24 inches

6 3. Protective Cover: Unless otherwise noted on the drawings, minimum concrete protective cover shall be as follows: a. Concrete deposited against earth or stonefill: 3 inches. b. Formed concrete exposed to weather or in contact with earth: 2 inches. 4. Splices and Intersection: a. Bars: All reinforcing bar splices and intersections shall be lapped as required by ACI 318 but not less than 36 bar diameters unless otherwise noted on the drawings. All splices not shown on the project drawings shall be subject to the approval of the Engineer. b. Welded Wire Fabric: Welded wire fabric shall be lapped transversely (end laps) a minimum of two full spacings of the cross wire and securely tied in place. Longitudinal laps (side laps) shall be lapped a minimum of one full spacing of the cross wires and securely tied in place. 5. Templates: Templates shall be provided and used for accurate placement of dowels for columns, pedestals, walls, etc. 6. Field Bending: Field bending or re-bending of reinforcing steel will not be permitted unless specifically authorized by the Engineer in writing. 7. Welding: When required by the drawings, welding of reinforcing steel shall conform to "Recommended Practice for Welding Reinforcing Steel, Metal Inserts and Connections in Reinforced Concrete Construction" (AWS D12.1). Welding of crossing bars (tack welding) will not be permitted. 8. Relocation: Bars may be moved as necessary to avoid interference with other reinforcing steel and embedded items. Relocation of bars shall be subject to approval of the Engineer. B. PLACEMENT OF DOWELS: Steel dowels at joints shall be uniformly spaced at 16 inches on center. Dowels shall be greased and placed in concrete in such a manner that 1/2 dowel is in each pour. Dowels shall be placed at mid depth of slab and anchored at right angles to the joint surface. C. SEQUENCING AND SCHEDULING: Reinforcing steel shall be placed in footings and foundations as soon as possible in order to minimize the time that excavations are left exposed to the elements

7 3.03 INSPECTION: A. The Engineer shall be given an opportunity to inspect the reinforcing steel in all formed concrete work prior to placing of concrete. The Contractor will be allowed to place footings and slabs on grade without delay for inspection CLEANING: A. ALL REINFORCEMENT shall be cleaned free of mud, oil, concrete splatter and other materials that may adversely affect or reduce bond prior to placement of concrete. B. RUST AND MILL SCALE: Normal amounts of tight rust and mill scale will be accepted as being satisfactory without cleaning or brushing provided the dimensions and weights, including heights of deformations of a cleaned sample shall not be less than required by the applicable ASTM specification. Loose rust and mill scale must be cleaned or brushed from reinforcement. (End of Section)