1113PLAIN AND LAMINATED NEOPRENE BEARING PADS

1113.01GENERAL REQUIREMENTS—

neoprene bearing pads.

grades, and laminate types indicated.

1113.02MATERIAL—

2, 3, 4, or 5 elastomer compound. Elastomer compound grades are defined by the testing requirements in Table A. Substitution of a higher grade of elastomer for a lower one is permissible. Provide elastomer compound conforming to Table A unless otherwise directed. Interpolate test requirements for any intermediate specified hardness. If the material is specified by its shear modulus, furnish material with a measured shear modulus that is within 15% of the specified value. For the purpose of defining limits for the tests in Table A, supply material with a consistent value of hardness. If the material is specified by its hardness, furnish material with a measured shear modulus that conforms to Table 14.7.5.2-1 of the LRFD Specification. When test specimens are cut from the finished product, the physical properties are allowed to vary fr om those specified in Table A by 10%. Conduct all material tests at 73F ± 4F unless otherwise noted. Conduct shear modulus tests according to Annex A of ASTM D4014.

to A36/A36M, ASTM A 1011, or equivalent, unless otherwise directed. Furnish laminates with a minimum nominal thickness of 16 gage. Do not make holes in plates for manufacturing purposes unless indicated.

continuous fibers. Provide a minimum thread count in either direction of ten threads per 25 threads per inch. Furnish fabric having either a crowfoot or an 8 Hardness Satin weave. Ensure each ply of fabric has a minimum breaking strength of 800 pounds per inch in each thread direction. Holes in the fabric are not allowed.

peel strength of 30 pounds per inch. Supply steel laminated bearing pads that develop a minimum peel strength of 40 pounds per inch. Perform peel strength tests according to ASTM D429, Method B.

1113.03FABRICATION—

appearance included in the latest edition of The ARPM Rubber Handbook for Molded, Extruded, Lathe Cut and Cellular Products, MO -1, published by the Association for Rubber Products Manufacturers; RMA F3 AND T.063 for molded bearing pads and RMA F2 for extruded bearing pads.

reinforcement as a unit in a mold. Bond and vulcanize bearing pads under heat and pressure. Ensure that the mold finish conforms to standard shop practice. Sand blast and clean the internal steel laminates to remove all surface coatings, rust, mill scale, and dirt before bonding, and ensure that the internal steel laminates are

free of sharp edges and burrs. For bearing pads that are designed to act as a single unit with a given shape factor, manufacture the bearing pads as single units. Repair all cavities left in the edges of the bearing pad from the manufacturing process by in -plant vulcanizing with neoprene material from the same lot as the bearing pad.

in large sheets and cut to size. Perform cutting in such a way to avoid heating the materials and to produce a smooth finish with no separation of the fabric from the elastomer. Furnish at least single ply fabric reinforcement for the top and bottom reinforcement layers and double ply for internal reinforcement layers. Place fabric parallel to the top and bottom surfaces. Ensure that the fabric is free of fo lds and ripples.

Ensure that cutting does not heat the material but produces a smooth finish.

the requirements of the plans and these Specifications. Provide a certified copy of the material test results. Mark each bearing pad (both reinforced and plain) in indelible ink or flexible paint. Include the orientation, the order number, lot number, bearing identification number, and elastomer type and grade number in the marking. Unless otherwise specified in the contract documents, place the markings on the face that is visible after erection of the bridge.

and as specified below.

TABLE A Neoprene Quality Control Tests Property Test Method Minimum Requirements Type 50 Type 60 Type 70 Physical Properties • Hardness (Shore A Durometer) • Tensile Strength, Min. psi • Ultimate Elongation, min. % ASTM D2240 ASTM D412 50 ± 5 2,250

60 ± 5 2,250

70 ± 5 2,250

Heat Resistance • Change in Durometer Hardness, max. points • Change in Tensile Strength, max. % • Change in Ultimate Elongation, max. % ASTM D573 70 h @ 212F

-15

-40

-15

-40

-15

-40 Compression Set • 22 h @ 212 F, max. % ASTM D395 Method B 35 35 35 Ozone • 100 pphm Ozone in Air by Volume, 20% Strain 100F ± 2F 100 h ASTM D1149 Method B, Procedure B1 No Cracks No Cracks No Cracks Low Temperature Brittleness • Grades 0 & 2

• Grade 3 Tested @ -40F • Grade 4 Tested @ -55F • Grade 5 Tested @ -70F No test required

ASTM D746 Procedure B

No Failure No Failure No Failure

No Failure No Failure No Failure

No Failure No Failure No Failure Instantaneous Thermal Stiffening • Grades 0 & 2 @ -25F • Grade 3 Tested @ -40F • Grade 4 Tested @ -50F • Grade 5 Tested @ -65F ASTM D1043 Stiffness(1) at test temperature not to exceed 4 times the stiffness measured at 73F.

Low Temperature Crystallation • Grade 0

• Grade 2, 7 days @ 0F • Grade 3, 14 days @ -15F • Grade 4, 21 days @ -35F • Grade 5, 28 days @ -35F

No test required

Quad Shear Test as described(2)

Stiffness(1) at test time and temperature not to exceed 4 times the stiffness at 73F with no time delay.

the text, refers to “shear modulus stiffness”. The word “stiffness” is used in Table A to cover both terms.

a randomly selected bearing pad. Use a 25% strain cycle and apply a complete cycle of strain with a period of 100 seconds. Discard the first 3/4 cycle of strain and determine the stiffness by the slope of the force deflection curve for the next 1/2 cycle of loading.

each lot of bearing pads. Provide test certificates from the supplier for each lot of steel or fabric reinforcement. Conduct low temperature tests as specified in Section 1113.03(f)4 for each lot of bearing pads. Visually inspect every finished bearing pad as specified in Section 1113.03(f)5. Conduct short-duration compression tests as specified in Section 1113.03(f)6 on every steel reinforced bearing pad. If required, conduct shear stiffness tests on material from a random sample of the finished bearings as specified in Section 1113.03(f)8.

hardness, tensile strength, ultimate elongation, heat resistance, compression set, and ozone resistance. Ensure that the bond to the reinforcement conforms to the requirements specified in Section 1113.02(d). Test the shear modulus of the material at 73F according to Annex A of ASTM D4014. Ensure that the measured shear modulus is within 15% of the specified value. If no shear modulus is specified, ensure that the hardness falls within the range given in Article 14.7.5.2 and Article 14.7.6.2 of the LRFD Specification. Instead of performing a shear modulus test for each batch of material, the manufacturer may, if permitted, provide certificates from tests performed on identical formulations within the preceding y ear.

D746), instantaneous low temperature stiffness tests (ASTM D1043), and low temperature crystallization tests (ASTM D4014) on grades 3, 4, and 5 elastomers. For grade 3 elastomers, instead of conducting low temperature crystallization tests, the manufacturer may provide certificates from low temperature crystallization tests performed on identical material within the last year, unless the tests are required. Conduct instantaneous low temperature stiffness tests (ASTM D1043) on grades 0 and 2 elastomers. If required, conduct low temper ature brittleness tests (ASTM D 746) and low temperatur e crystallization tests (ASTM D4014) on grades 0 and 2 elastomers. Perform all tests according to Table A and ensure the compound satisfies all limits for its grade.

with dimensional tolerances and for overall quality of manufacture. In steel reinforced bearing pads, protect the edges of the steel everywhere from corrosion.

1.5 times its maximum design load. Hold the load constant for 5 minutes, remove, and reapply for another 5 minutes. Visually examine the bearing pad while under the second loading. If the bulging pattern suggests laminate parallelism or a layer thickness that is outside the specified tolerances, or poor laminate bond, reject the bearing pad. If there are three or more separate surface cracks that are greater than 0 .08 inch wide and 0.08 inch deep, reject the bearing pad.

1.5 times its maximum design load for a minimum period of 15 hours. If during the test the load falls below 1.3 times the maximum design load, increase the test duration by the period of time for which the load is

below this limit. Visually examine the bearing pad at the end of the test while it is still under load. If the bulging pattern suggests laminate parallelism or a layer thickness that is outside the specified tolerances, or poor laminate bond, reject the bearing pad. If there are three or more separate surface cracks that are greater than 0.08 inch wide and 0.08 inch deep, reject the bearing pad.

and test the shear modulus of the material according to Annex A of ASTM D4014, or, if acceptable, conduct a comparable nondestructive stiffness test on a pair of finished bearing pads. Ensure that the measured shear modulus is within 15% of the specified value. If no shear modulus is specified, ensure that the hardness falls within the range given in Article 14.7.5.2and Article 14.7.6.2 of the LRFD Specification. If the test is conducted on finished bearing pads, compute the material shear modulus from the measured shear stiffness of the bearing pad, taking due account of the influence on shear stiffness of bearing pad geometry and compressive load.

to ASTM D3767, modified as follows: Measure dimensions 4 inches or less according to ASTM D3767 Procedure B. Measure dimensions greater than 4 inches according to ASTM D3767 Procedure C. Provide finished bearing pads within the following tolerances:

• Overall Height Design Thickness 1 1/4 inches or less Design Thickness over 1 1/4 inches

+1/8 inch +1/4 inch

• Overall Horizontal Dimensions 3 feet or less Over 3 feet

+1/4 inch +1/2 inch

• Thickness of Individual Layers of Elastomer (Laminated Bearing Pads Only) At any point within the bearing pads

±20% of design value but no more than ±1/8 inch

• Parallelism with Opposite Face Top and bottom Sides

0.005 rad 0.02 rad

• Position of Exposed Connection Members Hole, slots or inserts ±1/8 inch

• Edge Cover Embedded laminates or connection members +1/8 inch

• Thickness Top and bottom cover layer (if required) -0, the smaller of 1/16 inch and +20% of the nominal cover layer thickness

• Size Holes, slots, or inserts ±1/8 inch

with organic fiber as filler material. The fiber may be oriented or random (Type I), or in the form of fabric (single or multiple laminations, Type II). Certify as specified in Section 106.03(b)3. Furnish finished bedding material conforming to the following requirements:

Type I Type II

tensile strength not to exceed ±40% ±40%

high temperature preconditioning min. max. 10% 20% 0% 20%

compressed to rupture between flat plates 5,000 psi 8,000 psi

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