837ELASTOMERIC BEARING MATERIALS

720

All non-destructive testing required by these Specifications shall be performed by the Contractor

836.47& 836.48 Blank

836.49Painting

Shop coating shall meet applicable requirements of Section 521.

836.50Protection Of Machine Finished Surfaces

Machine-finished surfaces in general shall be shop painted except for the following: Driven pins and pin holes; surfaces in sliding contact; bronze, and steel surfaces opposing bronze in sliding contact; other surfaces as noted on the plans. Machine surfaces of steel not requiring paint should receive a heavy shop coat of Petrolatum meeting the requirements of ASTM D 217, NLGI Grade 2 or 3 or Military Specification C-16173D, Grade 1. Other approved coating may be used. Surfaces opposing bronze in sliding contact, if shipped assembled with bronze, shall be coated and assembled with the lubricant supplied by the bronze manufacturer. If not shipped assembled with bronze, such surfaces shall receive a shop coating, which shall be removed before field assembly. The lubricant furnished by the bronze manufacturer shall then be applied. No paint or protective coating shall be applied to bronze. ELASTOMERIC BEARING MATERIALS

837.01Description

Elastomeric bearings shall be classified by Type in accordance with the following: BEARING TYPE Plain Elastomer Layers of Elastomer With Internal Steel Laminate Plates Bearing Plate Vulcanized to the Elastomer PTFE Surfacing Bonded to the Bearing Plate on the Elastomer. Stainless Steel Surfacing Attached to a Second Bearing Plate. Type 1 X Type 2 X Type 3 X X Type 4 X X Type 5 X X X

837.02Required Physical Properties

The materials for the elastomeric bearings shall meet the requirements given in AASHTO M 251, Appendix X1. Physical property tests shall be performed in accordance with applicable AASHTO, ASTM, and ALDOT procedures.

The elastomer, unless otherwise specified, shall be 100% virgin polychloroprene (neoprene). Natural rubber, vulcanized rubber (natural or synthetic) or other synthetic rubber-like materials will not be accepted. The elastomer for Type 1 and Type 3 bearings (bearings without internal laminate plates) shall be 60 Durometer hardness. The elastomer for Type 2, Type 4, and Type 5 bearings (bearings with internal laminate plates) shall be 50 Durometer hardness. Where bearing plates are required, the elastomeric portion of the pad shall be hot bonded to the bearing plate during the vulcanization of the pad. This process shall form a bond such that removal of the elastomeric portion of the pad from the bearing plate will result in elastomer failure before bond failure.

Internal steel laminate plates, unless shown otherwise on the plans, shall have a nominal thickness of not less than 12 gage. ELASTOMERIC BEARING MATERIALS 721

Steel bearing plates shall be hot dipped galvanized coated in accordance with the requirements given in ASTM A 123. The surfaces of the plates that will be bonded to the elastomer shall be cleaned to SSPC 10 "near white metal finish" after galvanization and immediately prior to bonding. The cleaned bonding surface shall be protected from rust that will be detrimental to the strength of the bond. A portion of the galvanization shall be removed from the bearing plates to allow the field welding for the installation of the bearings. For each weld, a 1 inch {25 mm} wide strip of galvanization shall be removed. This strip of bare metal shall extend across the entire width of the bearing plate.

The PTFE shall be composed of 100 percent virgin (unfilled) polytetraflouroethylene polymer. The PTFE resin shall be 100 percent pure new material and shall comply with ASTM D 4894. No reclaimed material shall be used. The PTFE shall meet the following requirements: PHYSICAL PROPERTIES OF PTFE PHYSICAL PROPERTY ASTM TEST METHOD SHEET (UNFILLED) Specific Gravity D 792 2.16 ± 0.03 Melting Point ºF {ºC} D 4894 623 ± 2 {328±1} Tensile Strength psi {MPa} D 4894 2800 {19.3} Elongation at Break (%) D 4894 200 The thickness of the PTFE shall be at least 1/16 inch {1.58 mm} after compression. The PTFE shall be attached to the bearing plate by adhesive bonding using an adhesive that is approved by the Engineer, in accordance with the instructions of the adhesive's manufacturer. Prior to bonding, the surface shall be etched by an approved manufacturer using the sodium naphthalene or sodium ammonia process. The peel strength of the bond shall be not less than 20 pounds per inch {3.5 kN/m}, when tested in accordance with ASTM D 429 Method B. If shown on the plans, the PTFE shall be confined in a recess in the bearing plate for one half of the PTFE thickness. PTFE confined in a recess shall be at least 3/16 inch {4.76 mm} thick when the maximum dimension of the PTFE is less than or equal to 24.0 inches {610 mm}, and 1/4 inch {6.35 mm} when the maximum dimension of the PTFE is greater than 24.0 inches {610 mm}, unless shown otherwise on the plans. The finished surface of the PTFE shall be smooth, free from bubbles and shall conform to the tolerances shown.

The required thickness of the stainless steel sheet may be shown on the plans. If not shown, the thickness shall be at least 1/16 inch {1.58 mm} when the maximum dimension of the surface is less than or equal to 12.0 inches {305mm} and 1/8 inch {3.18 mm} when the maximum dimension is larger than 12.0 inches {305 mm}. The stainless steel surfacing shall meet the requirements of ASTM A 240, Type #304 and the requirements of ASTM A 480 and shall have a No. 8 Finish (mirror finish) on the side in contact with the PTFE layer. Unless otherwise shown on the plans, the coefficient of friction between the bearing element (bearing plate with PTFE) and the stainless steel shall not be more than 0.06 at 800 psi {5.5 MPa} compressive loading. The stainless steel component shall be furnished as one piece of steel if it is shown on the plans to be a single piece. After removal of the galvanization on the bearing plate in the footprint of the stainless steel sheet, each sheet shall be attached to the bearing plate by seal welding around the entire perimeter so as to prevent entry of moisture between the stainless steel sheet and the bearing plate. After welding, the bead and any damaged galvanized area shall be repaired as per the sprayed zinc (metallizing) requirements of ASTM A 780. Welds shall conform to the American Welding Society requirements for stainless steel. After welding, the stainless steel sheet shall be flat, free from wrinkles and in continuous contact with its sole plate.

Types 1, 2, 3, and 4 pads shall be fabricated in accordance with AASHTO M 251. Type 5 pads shall be fabricated in accordance with the manufacturer’s recommendations. STRUCTURAL PLATE FOR PIPE, PIPE-ARCHES AND ARCHES 722

Pads shall be manufactured in accordance with plan details and shop drawings with applied tolerances as established in AASHTO M 251. Type 5 bearing pads shall in addition to AASHTO M 251 meet the following tolerances: FLAT PTFE SLIDING BEARING TOLERANCES ITEM THICKNESS DIMENSION FLATNESS OR OUT-OF-ROUND PTFE -0.000" , +0.0063" {-0.00mm, +0.160mm} -0.000", +0.030" {-0.00mm, +0.76mm} 0.001 X Nominal Thickness Stainless Steel -0.000" , +0.0063" {-0.00mm, +0.160mm} -0.000", +0.125" {-0.00mm, +3.18mm} 0.001 X Nominal Thickness

837.03Marking, Sampling, and Testing

Bearings shall be divided into lots and marked in accordance with AASHTO M 251, Appendix X1 as modified in ALDOT-368 to allow pads of the same type but different sizes to be grouped together in a lot. Bearings less than 3 inches {75 mm} in thickness may have markings placed on the top surface in lieu of the side. Lots may contain up to 3 additional pads for sampling purposes. Sampling, for Departmental verification testing, shall be in accordance with ALDOT 368 and the ALDOT Testing Manual. In addition to ALDOT testing, manufacturers shall, as a minimum, test all lots to Level 1 of AASHTO M 251, Appendix X1. Manufacturers shall furnish certified test reports showing actual test results for all parameters found in Table X1 of AASHTO M 251. In addition, steel reinforced pads shall have test results covering the peel strength test and certification that all pads have been proof loaded and passed the requirements for Level 1 criteria, as well as a mill test report for the steel laminates showing the actual physical and chemical analysis for the heat of steel. Mill test reports shall also be submitted for all bearing plates. The manufacturer shall furnish certification that the Type 5 bearing assembly meets the requirement for the maximum allowable coefficient of friction between the PTFE and the stainless steel sheet. STRUCTURAL PLATE FOR PIPE, PIPE-ARCHES AND ARCHES

841.01Description

Corrugated metal structural plate pipe, pipe-arches, and arches shall meet requirements noted in this Section and the details shown on the plans. Acceptance of material will be based on job site inspection for workmanship and compliance with fabrication requirements. A certificate of compliance for each shipment as per AASHTO requirements will not be required; however, a copy of the manufacturer's analysis of the sheets used in the manufacture of the pipe shall be furnished. For correlation of specified plate thickness and allowable fill heights, see plan details.

Plates shall be formed to provide lap joints. The bolt holes shall be so punched that all plates having like dimensions, curvature, and the same number of bolts per meter of seam shall be interchangeable. Each plate shall be curved to the proper radius so that the cross-sectional dimensions of the finished structure will be as indicated on the plans. Plates for forming skewed or sloped ends shall be cut to give the angle of skew or slope specified. Burned edges shall be free from oxide and burrs, and shall present a workmanlike finish. Elongation of structural plate pipe may be accomplished by forming plates so that the finished pipe is elliptical in shape with the vertical diameter approximately five percent greater than the nominal diameter of the pipe. Plates for a pipe arch shall form a cross section made up of four circular arcs tangent to each other at their junctions and symmetrical about the vertical axis. The top shall be an arc of not more than 180