Section 4151. Steel Reinforcement
Use the size and type specified in the contract documents. Meet the requirements for the type and use specified. Use chairs, bolsters, and other support devices, either plastic or steel, that meet the requirements of Materials I.M. 451.01.
4151.02 PAVEMENT REINFORCEMENT.
Meet the requirements of Article 4151.03, and where mesh is specified, Article 4151.04.
1. Use epoxy coated bars coated according to Article 4151.03, C. Cut or sheared ends need not be recoated.
2. Use deformed bars meeting requirements of ASTM A 615, Grade 40 or 60 if the pavement tie bars are to be bent and later straightened. Bend the tie bars back reasonably straight. Replace tie bars broken during rebending by drilling a hole and setting the bar in epoxy, at no additional cost to the Contracting Authority.
1. Use plain round bars meeting requirements of:
· ASTM A 663, Grade 60 or higher,
· ASTM A 675, Grade 60 or higher, or
· ASTM A 615, Grade 40 or higher.
2. Approved manufacturers and suppliers of load transfer dowels and dowel assemblies are listed in Materials I.M. 451.03B, Appendix C.
3. Furnish dowels, with the exceptions of end of run and header joints, in approved assemblies as shown in the contract documents. Ensure all dowels, including end of run and header dowels, have an epoxy coating. Ensure the coating is applied by the electrostatic spray method complying with the requirements of AASHTO M 254, Type B, with a minimum coating thickness of 6 mils after cure. Epoxy powders approved for use are listed in Materials I.M. 451.03B, Appendix B. Perform welding and tack welding on reinforcement according to Article 4151.06.
4. The ends of dowels may be saw cut or sheared. The sawed and sheared ends need not be coated. If the dowel bars are saw cut, ensure they are free of burrs and projections. Also ensure the deformation of the bars from true round shape does not exceed 0.04 inches in diameter or in thickness.
5. Prior to delivery to the work site, the assemblies are to be dipped in a bond breaker meeting the requirements of Section 4137, 4138, or 4140. The bond breaker may be bituminous or paraffin.
6. Protect epoxy coated dowels in dowel assemblies stored outdoors, longer than 2 months either at fabricator or project site, from weather exposure and salt spray. Cover coated dowels in dowel assembly with a non-transparent or other suitable opaque protective material. Provide adequate ventilation to minimize condensation. Record on an identification tag the date coated dowels assemblies were placed outdoors. Do not use weathered, discolored, or faded dowel bars. Store dowel assemblies off the ground on pavement or wood supports. When stacking is necessary, place wood supports between assemblies or other method to ensure a stable stack.
C. Reinforcement For Bridge Approach Sections, Reinforced Paved Shoulders, and Full-Width Reinforcement of Pavements.
Comply with the following:
· Deformed bars meeting the requirements of ASTM A 615, Grade 40 or 60; or ASTM A 706, Grade 60,
· Epoxy coated, and
· Meet the requirements of Article 4151.03, except that cut or sheared ends need not be recoated.
4151.03 REINFORCEMENT FOR STRUCTURES.
1. Unless otherwise specified, use deformed bars meeting the requirements of ASTM A 615, ASTM A 706 or ASTM A 996. Use bars fabricated according to Article 2404.03, B.
2. Spirals of No. 5 (15) bars or smaller and any bars No. 3 (10) or smaller for stirrups or hoops of a specified shape may, at the Contractor's option, be:
· Material meeting requirements of ASTM A 1064 reinforcement specified above, or
· Steel meeting physical and chemical requirements of ASTM A 615, Grade 40.
3. For spirals in precast and prestressed concrete piling and all wire ties, use steel wire with a minimum tensile strength of 40,000 psi, with other properties such as to permit bending as shown in the contract documents.
4. When required by the contract documents, coat steel wire supports with:
· PVC according to ASTM A 933, or
· Epoxy according to ASTM A 884.
1. Comply with ASTM A 767, Class I coating with cutting and bending done prior to galvanizing and according to the requirements of Section 2404.
2. Galvanize tie wires and wire or pressed steel chairs to be used with galvanized reinforcing steel. Either turn up or coat the ends of chairs which may be exposed in the finished concrete. Stainless steel chairs, plastic coated carbon steel chairs, or other types of chairs may be approved by the Engineer. Galvanizing of hangers is optional (required only when to remain exposed), according Article 2412.03, A.
3. Handle bars according to ASTM A 767 in a manner to prevent damage to the galvanized coating. When coating damage is 2% or less of the surface area, repair it according to Materials I.M. 410. Replace bars with more than 2% of the surface area damaged.
C. Epoxy Coated Reinforcement.
1. Ensure reinforcement (deformed and plain) required to be epoxy-coated has a protective coating of epoxy applied by electrostatic spray method according to the requirements of ASTM A 775.
2. Acceptance and handling of epoxy-coated reinforcing steel reinforcement bars at the project site are to be according to the requirements of these specifications and the requirements of Materials I.M. 451.03B.
3. Thoroughly blast (near-white) clean reinforcing steel surfaces to be coated. Remove mill scale, rust, and foreign matter. Ensure the blast media produces a suitable anchor pattern profile (a depth of 2.0 to 4.0 mils). Apply the coating within 0.5 hour after cleaning.
4. Ensure blast media meets the requirements of ASTM A 775. A maximum of 10% steel shot may be added to blast media.
5. Ensure coating damage due to fabrication or handling at the fabricator facility is repaired using patching material meeting the requirements of Section 3.1 of ASTM D 3963. The fabricator is responsible for the repair.
6. Repair visible damage incurred during shipment, storage, and /or placement of epoxy-coated bars at the job site.
7. Use coating patch materials of organic composition consisting of a two-component liquid properly mixed that hardens to a solid form upon curing. Approved repair/patch compounds are listed in Materials I.M. 451.03B.
8. Repair damage to the coating caused by shipment, storage, and/or placement at the job site.
9. Ensure sheared ends/saw-cut ends of the coated bars have adequate coating, have no signs of surface rust or damage, and are repaired and/or coated with the same patching material that is used for repairing damaged coating.
10. The maximum amount of repaired, damaged areas is not to exceed 2% of the total surface area in each 1.0 linear foot of the bar. Should the amount of damage exceed the 2% in 1.0 linear foot, then remove that bar and replace with an acceptable bar. Coating the cut ends will not be included in the repair percentage.
11. Apply a minimum coating thickness of 7 mils to areas to be repaired.
12. Allow patches to cure (dry to the touch) before placing concrete over the coated bars.
13. Prepare the surface, repair it, and apply patches according to the resin manufacturer’s recommendations.
D. Storage, Handling, and Placement at the Job Site.
1. Comply with the following:
a. Store coated bars or bundles above ground on wooden or padded supports with padded timbers placed between bundles when stacking is necessary. Place supports to prevent sags in the bundles.
b. Ensure systems for handling (loading, unloading, storing) the coated bars at the job site have padded contact areas. Do not drop or drag coated bars or bundles.
c. Store coated and uncoated steel reinforcing bars separately.
d. Minimize handling and re-handling of the coated bars.
e. Tie coated bars using tie wire coated with epoxy, plastic, Nylon, or other non-conductive Materials that will not damage or cut the coating.
f. Use a non-conductive Material compatible with concrete to coat or fabricate bar supports or spacers.
2. Use a non-transparent material to cover coated bars if they will be exposed for 2 months or more. Ensure adequate ventilation is provided to minimize condensation under the cover.
E. Stainless Steel Reinforcement.
1. Stainless steel reinforcement bars shall be deformed and meet requirements of ASTM A 955 and be the grade, UNS designations, and types listed in Materials I.M. 452. Bars shall be heat treated using one of the three methods listed in ASTM A 955.
2. Supply bars free of dirt, mill scale, oil and debris. Stainless steel reinforcing bars shall be pickled to a bright or uniform light finish. Bars supplied displaying rust/oxidation, questionable blemishes, or lack of bright uniform pickled surface may be rejected.
3. Employ lifting, handling, securing and transport equipment and processes that will prohibit contamination of stainless steel reinforcing from fragments of carbon steel or other material residues/fragments. Minimize handling and re-handling of stainless steel reinforcing bars. Do not drop or drag stainless steel reinforcing bars or bundles.
4. Store stainless steel reinforcing bars or bundles above ground on wooden supports with timbers placed between bundles when stacking is necessary. Place supports to prevent sags in the bundles. Store stainless steel reinforcing separately from coated or uncoated reinforcing bars.
5. Fabricate and bend stainless steel bars using tools and equipment that have been thoroughly cleaned or otherwise modified to prohibit contamination from fragments of carbon steel or other material residues/fragments.
6. Protect stainless steel from contamination during construction operations including cutting, grinding, or welding above or in the vicinity of the stainless steel.
7. Stainless steel reinforcing bars shall not be permitted to come in direct contact with uncoated reinforcing bars, bare metal form hardware, or other bare or galvanized metals unless specifically approved herein or otherwise approved in writing by the Engineer. When practicable, stainless steel reinforcing shall maintain a minimum 1 inch clearance from bare or galvanized metals. When 1 inch clearance is not practicable, stainless steel reinforcing shall be isolated from contact with bare or galvanized metals by a wrap of electrical tape or other approved means. Protective wrap shall encompass the full perimeter of the bar and extend at least 1 inch in each direction past the point of closest contact between the stainless bar and dissimilar metal. Stainless steel reinforcing bars may be in direct contact with undamaged epoxy coated reinforcing bars. Stainless steel reinforcing bars may be in direct contact with shear studs on steel girders.
8. Bar Chairs.
a. Bar chairs for support of stainless steel reinforcing shall comply with one of the following:
1) Bar chairs fabricated from solid plastic, meeting requirements of Materials I.M. 451.01.
2) Bar chairs fabricated from stainless steel. Stainless steel materials for bar chairs shall be compatible with the type of stainless steel materials used for reinforcing bars.
3) Epoxy coated bar chairs meeting requirements of Materials I.M. 451.01, except where prohibited by the contract documents. Care shall be taken during installation of epoxy coated bar chairs to prevent damage to epoxy coating. Bar chairs exhibiting cracked or otherwise damaged epoxy coating shall be replaced.
b. Non-coated carbon steel bar chairs shall not be permitted to support or come into direct contact with stainless steel reinforcing.
9. Tie Wire.
a. Tie wire for stainless steel reinforcing shall comply with one of the following:
1) Tie wire coated with epoxy, plastic, nylon, or other non-conductive materials. Care shall be taken during installation of coated wire ties to prevent damage to protective coating. Wire ties exhibiting cracked or otherwise damaged protective coating shall be discarded and replaced with undamaged ties.
2) Stainless steel tie wire. Stainless steel materials for tie wire shall be compatible with the type of stainless steel materials used for reinforcing bars.
b. Coated wire ties or stainless steel wire ties as noted herein shall be required for bar tie locations in which a stainless steel reinforcing bar is present (includes stainless-to-stainless bar tie locations and stainless-to-epoxy coated bar tie locations.)
10. Prior to placing concrete, ensure reinforcing bars are clean and exhibit a bright finish free of contaminants, oxidation, or rust. Oxidation or rust on bar surface will not be permitted and shall be immediately brought to the attention of the Engineer.
11. At the discretion of the Engineer, isolated areas exhibiting minor oxidation or rust attributable to trace contaminants on bar surface shall be thoroughly cleaned and treated with pickling paste marketed for such application. Bars exhibiting evidence of oxidation/rust not attributable to trace contaminants on bar surface, or oxidation/rust otherwise suspected to have a negative impact on the intended performance and/or service life of the bar, may be rejected.
12. If welding and/or tack welding is employed in the placement of stainless steel reinforcement, the following requirements shall be met prior to welding:
a. Welding shall not be performed without prior approval of the Engineer.
b. Welding procedure suitable for the chemical composition and intended use shall be submitted to the Engineer for approval prior to welding.
c. Perform welding using a state certified welder.
d. Perform welding and/or tack welding in accordance with the requirements of the contract documents, and latest edition of AWS D1.6, including requirements for minimum preheat and interpass temperature.
4151.04 WIRE MESH REINFORCEMENT.
Comply with size and spacing and one of the following classifications, as required by the contract documents:
A. Uncoated Wire Mesh.
Meets the requirements of ASTM A 1064.
B. Vinyl Coated Wire Mesh.
Meet requirements of ASTM A 933.
C. Epoxy Coated Wire Mesh.
Meet requirements of ASTM A 884, Class A coating for concrete applications and ASTM A 884, Class B coating for mechanically stabilized earth applications.
4151.05 STEEL FOR PRESTRESSING CONCRETE.
Comply with one of the following classifications, as required by the contract documents:
A. Uncoated Seven Wire Stress Relieved Strand.
Meet the requirements of AASHTO M 203, except furnish a load elongation curve for each heat number delivered. Low relaxation strand described in the AASHTO M 203 Supplement may be furnished at the Contractor's option.
B. Uncoated Stress Relieved Wire.
Meet the requirements of AASHTO M 204.
C. High Strength Alloy Steel Reinforcement.
Meet the requirements of AASHTO M 275.
4151.06 WELDING REINFORCEMENT.
Unless specified elsewhere in the contract documents, comply with the following for welding and tack welding steel reinforcement or wire mesh:
A. Weld and/or tack weld according to Materials I.M. 558 and latest edition of the AWS D1.4 including table 5.2 for minimum preheat and interpass temperatures.
B. Engineer will review weld procedures. Do not start welding process until Engineer has approved weld procedures. Request a new review of weld procedures if any one variable of the essential procedure has been changed.
C. Use qualified/certified welders and tack welders.
D. Calculate carbon equivalent of reinforcing steel bars or wire fabric. Do not weld reinforcement with a carbon equivalent exceeding 0.55%.
E. Weld with Shielded Metal Arc Welding (SMAW), Gas Metal Arc Welding (GMAW), or Flux Core Arc Welding (FCAW).
F. Use other welding processes if approved by Engineer.
4151.07 Reinforcement Couplers.
Mechanical reinforcement couplers may be used when allowed by the contract documents or with the Engineer’s approval. Use couplers that meet requirements of Materials I.M. 451 and the following:
A. Strength Requirements.
1. Ultimate Tensile Strength of splice shall be minimum 90% of ultimate tensile strength of reinforcement bars.
2. Develop in tension at least 125% of the specified yield strength of the bars being spliced.
3. Maximum slip of coupler after being loaded to 30,000 psi tension and unloaded to 3000 psi tension:
· For bar size up to No. 14 (45) - 0.01 inches
· For No. 18 (60) Bars - 0.03 inches
B. Epoxy coated couplers shall be coated according to ASTM A 934. Other couplers shall have similar steel properties and same coating properties as reinforcement being spliced.
C. Install couplers following manufacturer’s requirements.