SECTION 560: ELASTOMERIC BEARING PADS
560.1 Description
This Work consists of providing, assembling, and installing ela stomeric Bridge bearing pads.
560.2 Materials
560.2.1 General
The Contractor shall provide bearing pad Material and testing i n accordance with the Contract and AASHTO’s LRFD Bridge Construction Specification , Section 18. The Contractor shall provide plain or laminat ed bearing pads reinforced with s teel or fabric laminates.
560.2.2 Elastomer
The elastomer compound used in t he construction of these beari ngs shall contain only virgin crystallization resistant polychloroprene (neoprene). A ll material shall be new with no reclaimed material incorpor ated in the finished bearing.
560.2.3 Steel Laminates
The Contractor shall provide steel laminates to the dimensions shown in the Contract documents and in accordance with ASTM A36 or ASTM A1011, Grade 36. Steel laminates shall be no less than 1/8 inch thick.
560.2.4 Certification
The Contractor shall furnish certified Laboratory test results on the elastomer properties of compound for both plain and laminated bearings. The require d tests are per AASHTO M 251-06 Table 1. For Bridges north of I-40 and including I-40, the elastomer compound shall be Grade 3. For Bridges south of I-40, the elastomer compound shall be Grade 2. Test shall be done on an annual basis or when the material Supplier change s. The Contractor shall provide copies of certified mi ll test reports for laminated bea ring steel and any required steel components.
560.2.5 Marking
Using indelible ink or paint that will remain intact after pad deformation, the Contractor shall mark each laminated bearing pad on a face that is visible after Bridge erection, with the following information: 1. Order number; 2. Lot number; 3. Bearing identification number; 4. Elastomer type; and 5. Grade number.
560.2.6 Acceptance Criteria
The following tests shall be performed on the actual bearing pa ds. One (1) bearing pad per lot shall be tested. Section 560: Elastomeric Bearing Pads Page 568 The bearing pad shall be tested per AASHTO M 251-06 Section 8.8 . 2 . T h e a v e r a g e compressive load shall be 2,250 psi for laminated bearing pads and 1500 psi for plain bearing pads. The bearing pad shall be tested per AASHTO M 251-06 Section 9.1 . Where the bearing strain exceeds ten percent (10%), the lot shall be rejected. I f the bearing pad design loads are not shown on the Contract Drawings, the test will not be requir ed. Testing is to be performed by the manufacturer Laboratory with the certified test results submitted to NMDOT.
560.2.7 Submittals
Working Drawings shall be submitted to the Project Manager 14 D ays prior to fabrication. Any resubmittal will require an additional seven (7) Days for r eview. The Contractor shall not proceed with fabrication until Working Drawings are approved.
560.2.8 Fabrication
The Contractor shall cast bearing pads with steel laminates as a unit in a mold, bonded and vulcanized under heat and pressure. The Contractor shall p rovide molds with a standard mold finish. The Contractor shall sandblast internal steel lam inates to remove surface coating rust and mill scale before bonding. The Contractor shall provi de internal steel laminates free of sharp edges and burrs, with a minimum edge cover of 1/8 inch . The Contractor shall manufacture as a single unit bearing pads designed to act as a single unit with a given shape. The Contractor may provide mol ded or extruded plain bearing pads or fabric-reinforced bearings pads vulcanized in large she ets, and cut to size. The Contractor shall cut without heating the Materials, and to prod uce a smooth finish in accordance with ANSI 250, with no fabric separation from the el astomer. The Contractor shall provide single ply fabric reinforcement at the top and bottom of the reinforced bearings and double ply for internal reinforcement l ayers. The Contractor shall provide fabric free of folds and ripples, and parallel to the t op and bottom surfaces. The Contractor shall provide fl ash tolerances, finishes, and ap pearances are in accordance with the current Rubber Handbook, published by the Rubber Manufacturer’s Association, Inc., RMA F3 and T.063 for molded bearings and RMA F2 for extruded bearings.
560.2.9 Tolerances
The Contractor shall build plain and laminated bearing pads in accordance with Table 560.2.9:1, “Bearing Pad Tolerances.” Table 560.2.9:1 Bearing Pad Tolerances Parameter description Tolerance requirements Overall Vertical thickness 1 1/4 inch or less Over 1 1/4 inch 0 inch to +1/8 inch 0 inch to +1/4 inch Bearing Pad Tolerances Parameter description Tolerance requirements Overall horizontal dimensions 36 inch and less Over 36 inch 0 inch to +1/4 inch 0 inch to +1/2 inch Individual layer thicknessa ± 20% of design value but no more than ± 1/8 inch Variations from a plane parallel to the theoretical surfaceb Topc Sides 0.005 radians 0.02 radians Position of exposed connection members 1/8 inch Embedded steel plates edge cover or connection members 0 in to +1/8 inch Hole, slot, or insert sizes + 1/8 inch Hole, slot, or insert positions 1/8 inch aElastomer-laminated bearing pads only. bAs determined by measurements at the bearing edges. cSlope relative to the bottom.
560.3 Construction Requirements
560.3.1 General
The Contractor shall ensure bearing pads in the completed Struc ture exhibit a compressive strain of no more than ten percent (10%). The Contractor shall place bearing pads on level surfaces. The Contractor shall correct misalignments in the support to form a level surface. The Contractor shall not weld steel girders or base plates to t he bearing pad sole plates unless there is more than 1 1/2 inch of steel between the weld and the elastomer. The Contractor shall not expose the elastomer or elastomer bond to temperatures greater than 400 °F.
560.4 METHOD OF MEASUREMENT—Reserved
560.5 Basis of Payment
The furnishing and installing of elastomeric bearing pads will be considered Incidental to the completion of the Work and no measurement or direct payment will be made therefore. Section 561: Elastomeric Compression Joint Seals Page 570