544REINFORCEMENT FOR CONCRETE

New Hampshire Department of Transportation Standard Specifications – 2016 Description

1.1This work shall consist of furnishing and placing reinforcement for concrete as shown on the plans or ordered.

1.1.1 Manufacturers of reinforcing steel must participate in, and maintain compliance with, the AASHTO National Transportation Product Evaluation Program (www.ntpep.org) that audits producers of reinforcing steel. Materials

2.1Bar reinforcement shall be Grade 420 (Grade 60) or as shown on the plans.

2.1.1 Billet-steel bars shall conform to AASHTO M 31. 2.1.2 Rail-steel bars shall conform to AASHTO M 322M.

2.2Welded steel wire fabric shall conform to AASHTO M 55.

2.3Bundled reinforcement shall be used only as shown on the plans or with written permission.

2.4Epoxy Coated Reinforcing Steel.

2.4.1 Epoxy coated reinforcing steel shall meet the requirements of ASTM D3963. 2.4.2 A written certification by the manufacturer of the powdered epoxy resin attesting to the ASTM D3963 requirements shall be provided. 2.4.2.1 The certificate shall also contain the insignia or other similar statement that the plant is a currently approved fusion - bonded epoxy coating applicator, as defined by the Concrete Reinforcing Steel Institute (CRSI) Plant Certification Program. 2.4.3 The epoxy coating applied to the bars shall be uniform and smooth and shall provide a film thickness of 10 ± 2 mils after curing. 2.4.4 All chair and bar supports used for the installation of epoxy coated reinforcing bars shall be epoxy-coated, vinyl-coated, or plastic-coated wire bar supports. Plastic slab bolster bar supports may be utilized for installing epoxy coated reinforcing bars. Continuous plastic bar supports between the top and bottom mats are not acceptable.

2.5Synthetic Fiber Reinforcement. Synthetic fiber reinforcement shall be a product as included on the Qualified Products List.

Construction Requirements

3.1Bar list. The Department’s bar list and bending schedule are made for the purpose of arriving at an estimate of quantities.

The Contractor shall verify the quantity, size, and shape of the bar reinforcement against the structure drawings and make the necessary corrections, if any, before ordering. Errors in the bar list and bending schedule shall not be cause for adjustment of Contract unit price.

3.2Surface condition of reinforcement. The reinforcing steel, at the time concrete is placed, shall be free of dirt, paint, oil, or

other organic materials that may adversely affect or reduce bond. Metal reinforcement coated with firmly bonded rust, mill scale, or a combination of both shall be considered satisfactory provided the minimum dime nsions and weight of a hand wire -brushed test specimen are not less than the applicable specification requirement. Rust or mill scale which is difficult to remove by vigorous scrubbing with a wire brush shall be considered firmly bonded to the steel.

3.3Bending. Unless otherwise permitted, all reinforcing bars shall be bent cold. Bars partially embedded in concrete shall not

be field bent except as shown on the plans or permitted. Only competent people shall be employed for cutting and bending, and proper appliances shall be provided for such work. Should the Engineer approve the application of heat for field bending reinforcing bars, precautions shall be taken to assure that the physical properties of the steel will not be materially altered.

3.4Placing and fastening. Reinforcing steel shall be free from mortar and other objectionable substances, shall be accurately

placed as shown or ordered, and shall be securely blocked and tied unless otherwise permitted. Blocking shall be by rust-resistant chairs unless otherwise permitted. Tack welding will be prohibited except upon special written approval of the Engineer. This provision also prohibits welding form ties to the reinforcement. 3.4.1 Reinforcing steel for bridge decks shall be epoxy coated unless otherwise shown on the plans. Bridge deck reinforcing steel shall be placed on epoxy or plastic- coated steel wire supports in accordance with 2.4 and the Concrete Reinforcing Steel Institute Manual of Standard Practice. The bottom reinforcing shall be supported on type SB supports with the end of the supporting wire lapped to lock the last legs of adjoining units. The top reinforcing shall be supported by type CHCU bar supports placed between the top and bottom mats. The ends of the top supporting wire shall be lapped. The supports shall be sized and spaced to allow for the minimum cover of the reinforcing bars called for on the plans. At least 50 percent of the junctions of the reinforcing mat shall be tied.

New Hampshire Department of Transportation Standard Specifications – 2016 3.4.2 If plain reinforcing steel for the bridge deck is called for on the plans, then plastic protected or stainless steel protected supports may be used to support the bottom reinforcing mat and bright basic bar supports may be used between the top and bottom mats. 3.4.3 Concrete shall not be placed in any member until the placement of the reinforcing steel has been inspected and approved.

3.5Splices. Reinforcing steel shall be furnished in the full lengths indicated on the plans unless otherwise permitted. Splices

shall be made as shown on t he plans or as permitted. No splices will be permitted at points where the section does not provide a minimum distance of 2 ” between the splices and the nearest adjacent bar or surface of the concrete. The bars shall be rigidly clamped or wired at all splices. Sheets of metal mesh shall overlap each other sufficiently to maintain uniform strength and shall be securely fastened at the ends and edges. 3.5.1 Splices made with mechanical connectors shall be as detailed on the plans or as permitted and shall develop an ultimate strength at least 125% of the specified yield strength of the reinforcing bar being spliced. The minimum concrete cover over the reinforcing steel as shown on the plans shall be maintained at the mechanical splice. 3.5.1.1 The Contractor shall submit two mechanical connectors connecting two 12” sections of reinforcing steel of each size per lot per project. Connector and reinforcing steel assemblies will be tested by the Department.

3.6Handling, fabrication, and repair of epoxy coated reinforcing steel shall be in conformance with the applicable sections of

ASTM D3963. 3.6.1 If stored outdoors, the bars shall be covered for protection against the elements and in such a manner that condensation does not form on the bars. The bars shall not be exposed to sunlight for periods exceeding two months.

3.7Epoxy coated reinforcing steel which requires cutting shall be sawn. No flame -cutting will be allowed. Cut ends of bars

shall be recoated with epoxy as soon as possible and before visible oxidation occurs.

3.8Synthetic fiber dosage rate. The dosage rate shall be 7 lb/cy unless otherwise approved, in writing, by the Engineer.

Method of Measurement

4.1Reinforcing steel of the type specified, except reinforcing steel (roadway), will not be measured, but shall be the pound final

pay quantity in accordance with 109.11 for reinforcing steel required as shown on the plans. Reinforcing steel (roadway) will be measured by the pound of reinforcing steel placed as shown on the plans or ordered. The theoretical weight of reinforcing steel will be computed based on the following table:

4.2Synthetic fiber reinforcement will not be measured but shall be the pound final pay quantity complete in accordance with

109.11for the dosage rate specified

Basis of Payment

5.1Reinforcing steel of the type specified, except reinforcing steel (roadway), are final pay quantity items and will be paid for

at the Contract unit price per pound complete in place in accordance with 109.11. The accepted quantity of reinforcing steel

other material used for fastening reinforcement in place, and no allowance will be made for additional splices or permitted substitutions. 5.1.1 For mechanical splice bars no allowance will be made in excess of the length detailed on the plans for the additional weight required to manufacture and provide a mechanical splice to the plan specifications.

Table 544-1 - Reinforcing Steel Weight - English Size Bar # 3 4 5 6 7 8 9 10 11 14 18 Lb. per Linear Foot

0.376

0.668

1.043

1.502

2.044

2.670

3.400

4.303

5.313

7.65

13.60

New Hampshire Department of Transportation Standard Specifications – 2016

5.2Synthetic Fiber Reinforcement of the type specified is a final pay item and will be paid for at the contract unit price per pound

complete in place in accordance with 109.11.

5.3Structural steel. In reinforced concrete structures that have no structural steel bid items, structural steel will be paid for at

the unit price per pound bid for reinforcing steel, unless otherwise indicated in the Contract.

Pay items and units: 544. Reinforcing Steel (F) Pound

544.1Reinforcing Steel (Roadway) Pound

544.11Reinforcing Steel-Mechanical Connectors (F) Pound

544.2Reinforcing Steel-Epoxy Coated (F) Pound

544.21Reinforcing Steel-Epoxy Coated Mechanical Connectors (F) Pound

544.7Synthetic Fiber Reinforcement (F) Pound

New Hampshire Department of Transportation Standard Specifications – 2016

Description

This work shall consist of furnishing and welding steel shear connectors to structural steel for use in composite beam

construction as shown on the plans. All requirements of this section apply to studs except for structural shapes, as noted. Materials

General Requirements for Studs.

2.1.1 Studs shall be of suitable design for arc welding to steel members with the use of automatically timed stud welding equipment. The dimensions for standard headed type round studs shall conform to Table 547-1.

Table 547-1 - Dimensions of Standard - Type Shear Connectors Standard dimensions, inches Shank diameter Head diameter Minimum head height 3/4” 1-1/4” 3/8” 7/8” 1-3/8” 3/8” 2.1.2 An arc shield (ferrule) of heat resistant ceramic or other suitable material shall be furnished with each stud. The material shall not be detrimental to the welds or cause excessive slag and shall have sufficient strength so as not to crumble or break due to thermal or structural shock before the weld is completed. 2.1.3 A suitable deoxidizing and arc stabilizing flux for welding shall be furnished with each stud, either attached to the end of the stud or combined with the arc shield, for automatic application in the welding operation. 2.1.4 Only studs with qualified stud bases shall be used. (The stud base is the stud tip at the welding end, including flux, and 1/8” of the body of the stud adjacent to the tip). A stud base, to be qualified, shall have passed the test prescribed in Annex VI, AASHTO/AWS D1.5. The arc shield used in production shall be the same as used in qualification tests or as recommended by the manufacturer. Qualification of stud bases in accordance with Annex VI, AASHTO/AWS D1.5, shall be at the manufacturer’s expense. 2.1.5 Finish shall be produced by heading, rolling, or machining. Finished studs shall be of uniform quality and condition, free of injurious laps, fins, seams, cracks, twists, bends, or other injurious discontinuities. Radial cracks or bursts in the head of a stud shall not be the cause for rejection, provided that the cracks or bursts do not extend more than half the distance from the head periphery to the shank, as determined by visual inspection.1 (Footnote 1. Heads of shear connectors or anchor studs are subject to cracks or bursts, which are names for the same thing. Cracks or bursts designate an abrupt interruption of the periphery of the stud head by radial separation of the metal. Such interruptions do not adversely affect the structural strength, corrosion resistance, or other functional requirements of headed studs.) 2.1.6 Only bases qualified under Annex VI, AASHTO/AWS D1.5, shall be used. When requested by the Engineer, the Contractor shall provide the following information:

Mechanical Requirements for Studs.

2.2.1 Studs shall be made from cold drawn bar stock conforming to the requirements of AASHTO M 169 (ASTM A 108), Grades 1010 through 1020, inclusive, either semi-killed or killed deoxidation. 2.2.2 Studs shall conform to mechan ical property requirements of Table 547 -2. At the manufacturer’s option, mechanical properties of studs shall be determined by testing either: (1) the steel after cold finishing, or (2) the full diameter finished studs. Table 547-2 - Mechanical Property Requirements for Studs* Tensile strength 60,000 psi min. Yield strength (0.2% offset) 50,000 psi min. Elongation (% in 50,000 psi ) 20% min. Reduction of area 50% min.