- 813 - SECTION 1021 -- EPOXY COATED REINFORCING STEEL
1021.01 Description
1.Epoxy coated bars for concrete reinforcement shall conform to the requirements of ASTM A 775/A 775 M, Section 1020, and as shown in the contract. The bars shall be free of cont aminants such as oil, grease, paint, slivers, or any other imperfections wh ich may be detrimental to the coating process.
2.All reinforcing bars furnished under this item shall be given a protective coating of a fusion bonded epoxy resin.
1021.02 Material Characteristics
1.The coating shall be applied as an electrostatically charged dry powder sprayed onto a grounded steel bar using an electrostatic spray gun. The powder may be applied to either a hot or cold bar. The coated bar shall be given a thermal treatment specified by the manufacturer of the epoxy resin which will provide a fully cured finished coating.
2.The coating material shall be a powdered epoxy resin prequalified by evaluation as described in ASTM A 775/A 775 M. Tests shall be performed by the National Bur eau of Standards (NBS), a qualified independent testing laboratory, or a state laboratory approved by the Department’s Materials and Research Div ision. Approval of material by an independent or state laboratory is subject to the Engineer's review of the test data.
3.The manufacturer of the epoxy re sin shall also supply the coating applicator with all other information and recommendations essential to the proper use and performance of the po wdered resin as a coating. An authorized representative of the m anufacturer shall provide written certification to the applic ator that the powdered resin furnished for coatings is the exact formulation that was prequalified by the NBS or other testing agency.
4.At the request of the Engineer , the coating applicator shall provide a representative 7 ounce (200 g) sample of the resin powder used to coat each lot of bars. The sample shall be pa ckaged in an air-tight container with identification by lot number.
5.The approved powdered epoxy resins are on the Department’s Approved Products List.
6.A suitable patching material com patible with the coating and inert in concrete shall be made available to th e Contractor by the manufacturer of the epoxy resin for repair of damaged c oating areas at the applicator's plant or in the field. The patching or repair shall be performed in accordance with the recommendations of the material manufacturer.
7.A film thickness after curing of 7 to 12 mils (180 to 300 m) shall be applied in a uniform, smooth coat with no discontinuities, except as provided herein. Thickness of the film shall be measured on a representative number of bars from each production lot by the same method outlined in ASTM G 12 for measurement of film thickne ss of pipeline coatings on steel.
8.The coating shall be checked a fter curing for continuity of coating and shall be free from holes, voids, co ntamination, cracks, or other damaged areas. The average number of holidays per foot (300 mm) shall not exceed
1021.02 Epoxy Coated Reinforcing Steel
- 814 - one holiday per foot (300 mm) of coat ed bar. An in-line 67.5 volt DC powered detection system with an audible or visual signal shall be used in accordance with the manufacturer's in structions to check the coating for holidays and other defects.
9.Flexibility and Adhesion:
a.The flexibility and adhesion of the coating shall be evaluated on samples of all the bar sizes for each day's production lot.
b.The coated bars shall be capable of being bent 120 degrees around a mandrel of the size specified in Table 1021.01.
c.The bend test shall be made at a uniform rate. d. The coating on the bars shall sh ow no evidence of cracking or separation from the bar. If a sample's c oating shows evidence of cracking or separation, 2 retests shall be conduct ed on random samples from the same day's production lot.
e.If the results of both retest s meet specified requirements, the coated bars represented by the sample shall be accepted. Table 1021.01 Bend Test Requirements English Metric Bar No. Mandrel Diameter (inches) Bar Mandrel Diameter (millimeters) 3 3 4 4 10 75 13 100 5 5 16 125 6 6 19 150 7 7 22 175 8 8 25 200 9 9 29 230 10 10 32 250 11 11 36 280 14 17 43 430 18 23 57 580
10.The bending test shall be conducted at room temperature after the specimen has been exposed to room temperature for a sufficient time to insure that it has reached thermal equi librium. A temperature in the range of 68°F to 86°F (20 C to 30C) shall be considered room temperature.
11.The coating applicator shall ensure that samples for the bend test will not short the bar lengths specified in the contract.
1021.03 Procedures
1.The surface of the bars to be coated shall be clean and free from rust, scale, oil, grease, and similar contaminants.
2.The surface shall be blast cleaned to a near-white metal in accordance with the Steel Structure Painting Council Surface Preparation Specifications SSPC-SP10. Epoxy Coated Reinforcing Steel 1021.03 - 815 - 3. All traces of dust and grit fr om the blasting shall be removed.
4.The coating shall be applied to the cleaned surface as soon as possible after blasting and before visible oxidation of the surface occurs. However, in no case shall the applic ation of the coating be delayed more than 8 hours after blasting without specific approval of the Engineer.
5.In order to protect the c oated reinforcement from damage, the Contractor shall use padded or no nmetallic slings and padded straps. Bundled bars shall be handled in a manner which will prevent excessive sagging of bars which will damage the coating. If circumstances require storing coated steel reinforcing bars outdoors for more than two months, protective storage measures shall be implemented to protect the material from sunlight, salt spray and weather exposure. Coated steel reinforcing bars, whether individual bars or bundle s of bars, or both, shall be covered with opaque polyethylene sheeting or other suitable opaque protective material. For stacked bundles, the protective covering shall be draped around the perimeter of the stack. The covering shall be secured adequately, and allow for air circulation around the bars to minimize condensation under the covering. Coat ed steel reinforcing bars, whether individual bars or bundles of bars, or both, shall be stored off the ground on protective cribbing. The bundled bars sh all not be dropped or dragged. If, in the opinion of the Engineer, the coated bars have been extensively damaged, the material will be rejected. The Contractor may propose, for the approval of the Engineer, alternate precautionary measures.
6.The Engineer may defer final in spection and approval of the bar coating integrity and repairs until the ba r mat is in place and all handling is completed. A reasonable amount of coating damage due to fabrication and handling may be allowed depending on the number, extent, size, and location of such damaged areas. The Engineer shall be the sole judge of which imperfections in the coating need not be repaired.
7.The bars shall be fabricated and placed as shown in the contract and as specified in Section 707.
8.Epoxy Repairs:
a.Patching materials supplied or recommended by the manufacturer of the powdered resin sha ll be used to repair the coating and shall be applied to provide a minimum film thickness of 5 mils (125 m) over the bare area. Areas to be patched shall be clean and free of surface contaminants. They shall be properly treated in accordance with the resin manufacturer's recommendations befor e detrimental oxidation occurs.
b.Care should be taken during the patching procedure to assure that the coating thickness on the area adj acent to the patched area does not exceed 15 mils (375 m). Extensive areas of damaged coating, exceeding that which is unavoidable in careful handling and shipping, may be cause for rejection of the damaged bars.
c.In no case, however, shall the total bar surface area covered by patching material exceed 5%. (The 5% total bar surface area is the combined area for repairs done in the fabricator's shop and those done in the field.)
d.Proper repairs shall be the Contractor's responsibility even when the work is done by an applicator , fabricator, or other subcontractors.
1021.03 Epoxy Coated Reinforcing Steel
- 816 - 9. The identification of all re inforcing bars (manufacturer, heat number, and size) shall be maintained by the fabricator throughout the fabrication and coating process to assu re that the coated, fabricated bars are identified with proper tags for final shipment to the job site (tags should show size, heat number, and mark).
10.Certification: a. The coating applicator shall furnish with each shipment a written certificate stating that all ba rs have been coated in accordance with the resin manufacturer's recomm endations and these Specifications .
b.The certification shall incl ude for each bar size the preheat temperatures, cure times, thickness charts, holidays detected, and bend test results.
1021.04 Acceptance Requirements
1.Plant Approval:
a.A plant intending to supply epoxy coated reinforcing steel under these Specifications shall be in spected and approved by Department’s representatives before maki ng shipments to job sites. The plant shall notify the Department’s Materials and Research Division 30 days before processing any material. A date and time of inspection will be arranged by the Department’s Materials and Research Division and the plant.
b.Once a plant is inspected and approved, the applicator may ship the coated bars on the basis of a certificate of compliance which lists the material shipped and states that the material complies with these Specifications.
c.The inspection and approval of a plant does not constitute a blanket-type approval. The coating applicator's plant will be subject to additional in-plant inspections if, at an y time, in the opinion of the Engineer, the quality of the coated bars ap pears to be below specification requirements.
2.Coated bars will be inspected at the destination before any bars are incorporated in the work.
3.The coated bars will be inspected on the job site for handling defects, coating thickness, and continui ty of coating. A 67.5 volt DC holiday detector will be used for determinati on of continuity of coating.
4.In addition to the testing done at the coating applicator's plant (continuity, flexibility, adhesion, and film thickness), two 6 foot (1.8 m) samples of the coated bar (for tension te sting and bend testing) of each size bar and each heat number shall be sent to the Department’s Materials and Research Laboratory, Lincoln, Nebraska. These bars will be properly identified with tags showing the size and heat number. - 817 - SECTION 1022 -- DOWEL BARS
1022.01 Description
1.Coated dowel bars for use across transverse joints shall conform to the requirements of AASHTO M 254.
2.Coated dowel bars for use across transverse joints shall consist of a steel core with an organic covering and shall comply with the requirements of AASHTO M 254, Corrosion Resistant Coated Dowel Bars except:
a.The steel cores shall be sm ooth round bars of the diameters shown in the contract and shall comply with ASTM A 615/A 615M, Grade 40 or 60 (300 or 420). ASTM A 36, Grade 36 steel is an acceptable substitute, provided the steel meets or exceeds the chemical and mechanical requirements of ASTM A 615, Grade 40.
b.The coating on the latera l surface of the dowel may be eliminated for approximately 2 inches (50 mm) on one end of the dowel for welding purposes. Sheared or cut ends of fabricated dowels may be coated or un-coated, at the discretion of the fabricator or supplier.
c.Both Type A and Type B coated dowel bars shall be coated with a bond breaker shown on the D epartment’s Approved Products List, dipped in asphalt or paraffin, or greased in accordance with the specified requirements as shown in the contract.
1022.02 Acceptance Requirements
1.A plant supplying coated dowel bars under these Specifications shall meet the Acceptance Requirement s as set forth in Section 1021 for Epoxy Coated Reinforcing Steel. A certification by the manufacturer of the coating material and/or the coating app licator is required. The certification shall consist of a statement to the effect that the coating material represented conforms to AASHTO M 254 and the requirements in this Section. The certifications shall be fu rnished in triplicate and include copies of the test results. The c oating applicator shall also furnish 3 copies of the mill test showing physical and chemical test results of the steel used in the fabrication of t he coated bars.
2.In addition to these certificates , two 6-foot (1.8 m) samples of the coated bar (for tension testing and bend testing) of each size bar and each heat number shall be sent to the De partment’s Materials and Research Laboratory, Lincoln, Nebraska. These bars will be properly identified with tags showing the size and heat number.
Source: Nebraska Standard Specifications for Highway Construction, 2017 Edition. Pages 847–850 of 1,048.