Elastomer for Heavy Engineering Applications

(a)Laminated Bearing Sandwich structure between elastomer and steel plate Widely used because it is able to prevent & reduce the movement of the bridge due to few factors (earthquake, creep, etc)

The number of steel plate, will increase the amount of load that can be sustain by the bridge

(b) Plain Pad Bearing Consist of rubber, without the steel plate

( c ) Strip bearing “Strip bearing” similar with “plain pad bearing” but the length of the bearing is longer than its width.

( d ) Pot Bearing “Pot bearing” – bearing which consists of solid rubber block and it is located in between metal piston and metal cylinder.

Pot Bearing

Plain Pad Bearing Laminated Bearing

Example the needs of good bridge bearings Benicia-Martinez Bridge The bearing for this bridge Increased to 53 inch whenever sustained 5 mil. Lbs loads.

Main materials used as bridge bearing: ELASTOMER

Function of Elastomer absorb the vibration allow the changes in the length of bridge ease of installation used to cover the metal plate (for laminated bearing)

Types of Elastomer used as bridge bearings Natural Rubber HDRB ( High Damping Rubber ) Neoprene SBR EPDM NBR

Why Elastomer? Long lasting Good in impact absorption Good bonding with metal Good resistance to ageing Good tearing properties Good physical properties sesuai untuk panas dan sejuk Good resistance to oil and chemicals

Disadvantages Expensive (especially for rubber with high resistance to ageing) Can be attack by:  ester  ketone  hydrocarbon with nitrogen  aromatic

Physical Properties Natural Rubber SBREPDMNeopreneNitrileUrethaneSiliconeFluorocarbon Specific Gravity to to to 1.95 Durometer, Range Tensile StrengthEF-GVG EF-G VG ElongationVG-EGGGGG-VGVG-E F-G Compression SetGGGF-GGG-E Heat ResistanceFF-GVG-EF-GG E E Resilience or ReboundEF-GGVGF-GF-EG F Impact ResistanceEEGGFG-EP-G E Abrasion ResistanceEG-E EP-F F-G Tear ResistanceEFF-G EP-F F Cut GrowthEGGGGG-EP-F Flame ResistancePPPGPP-FF-G VG-E Impermeability, GasFFF-G GP-FF-G E Weathering Resistance P-FFEVGF-GG-EE E Low Temperature Limit* -10° TO - 50°F 0° TO -50°F -20° TO - 60°F -10° TO - 50°F -30° TO - 40°F -10° TO - 50°F -65° TO - 150°F +10° TO -40°F High Temperature Limit* 158° TO 225°F 300° TO 350°F 225°F275°F250°F 400° TO 550°F 400° TO 450°F Comparison of physical properties of polymer P = PoorF = FairG = Good VG = Very Good E = Excellent

Neoprene = polychloroprene First Choice

Polychloroprene before vulcanization

Polychloroprene after vulcanization

Natsyn Zink oxide 3.0 stearic acid 2.0 Wingstay 100 – AZ 1.0 VANOS 3C 2.0 VANWAX H 2.0 HAF (N-330) carbon black 50.0 aromatic oil 10.0 Sulphur 0.5 MOFAX 1.9 TOTAL NEOPRENE PADS: FORMULATION

Properties, cured C Hardness, shore A 62 Tensile, MPa(psi) 26(3750) Elongation,% 650 Density, Mg/m Tear strength, Die C, kN/m (pli) 68(390) Compression set after 22 (158F) Method B, % Set 13

Methodology in preparing the laminated bearing

Preparation of rubber compound- according to the right composition Prepare the metal plate Apply the bonding agent to the metal plate Prepare the rubber compound and metal plate Compression Moulding Testing ( to test the quality and the properties)