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I1 9-31.8 Bearing Pads <br /> 2 9-31.8(1) Elastomeric Pads <br /> t 3 Elastomeric pads shall conform to the requirements of AASHTO M251 unless <br /> 4 otherwise specified in the Plans or Special Provisions. The elastomer shall be <br /> 5 low-temperature Grade 3 and shall not contain any form of wax. Unless <br /> I <br /> 6 <br /> 7 otherwise specified in the Plans or Special Provisions, the elastomer shall <br /> have a shear modulus of elasticity of 165 psi at 73°F. <br /> 8 <br /> I <br /> 9 <br /> 10 All elastomeric pads with steel laminates shall be cast as units in separate <br /> molds and bonded and vulcanized under heat and pressure. Corners and <br /> 11 edges of molded pads may be rounded at the option of the Contractor. Radius <br /> I 12 at corners shall not exceed % inch, and radius of edges shall not exceed 1/8 <br /> 13 inch. Elastomeric pads shall be fabricated to meet the tolerances specified in <br /> 14 AASHTO M251. <br /> 15 <br /> I16 Shims contained in laminated elastomeric pads shall be mill rolled steel sheets <br /> 17 not less than 20 gage in thickness with a minimum cover of elastomer on all <br /> 18 edges of: <br /> I 19 <br /> 20 1/4 inch for pads less than or equal to 5 inches thick and, <br /> 21 <br /> I 22 1/2 inch for pads greater than 5 inches thick. <br /> 23 <br /> 24 Steel shims shall conform to ASTM A1011, Grade 36, unless otherwise noted. <br /> I 25 Ail shim edges shall be ground or otherwise treated so that no sharp edges <br /> 26 remain. <br /> 27 <br /> I <br /> 28 <br /> 29 9-31.8(2) Polytetrafluoroethylene (PTFE) <br /> PTFE shall be unfilled (100-percent virgin) PTFE or fiberglass fiber filled PTFE <br /> 30 (or woven fabric PTFE for disc or spherical bearing assemblies) conforming to <br /> 31 Section 18.8 of the AASHTO LRFD Bridge Construction Specifications, and the <br /> I 32 following additional requirements: <br /> 33 <br /> 34 1. PTFE shall be unfilled (100-percent virgin) PTFE except where filled <br /> I <br /> 35 PTFE is specified in the Plans. <br /> 36 <br /> 37 2. Filled PTFE shall be 3omposed of PTFE resin uniformly blended with <br /> I 38 15-percent maximum fiberglass fiber. <br /> 39 <br /> 40 3. The substrate shall limit the flow (elongation) of the confined PTFE to <br /> I 41 not more than 0.009-inch under a pressure of 2,000 psi for 15- <br /> 42 minutes at 78°F for a two-inch by three-inch test sample. <br /> 43 <br /> 1 <br /> 44 <br /> 45 4. Unfilled PTFE shall have a hardness of 50 to 65 Durometer D, at <br /> 78°F, in accordance with ASTM D 2240. <br /> 46 <br /> 47 5. The PTFE may be dimpled. <br /> I48 <br /> 49 9-31.8(3) Pre-Formed Fabric Pad <br /> 50 Pre-formed fabric pads shall be composed of multiple layers of duck, <br /> I 51 impregnated and bound with high-quality oil resistant synthetic rubber, <br /> 52 compressed into resilient pads. The pre-formed fabric pads shall conform to <br /> 53 MIL C 882 and the following additional requirements: <br /> I54 <br /> HOT MIX ASPHALT OVERLAY-2018 PAGE 51 OF 53 March 6, 2018 <br /> I WORK ORDER#3667 <br /> AMENDMENTS TO STANDARD PROVISIONS <br />