THE ASSESSMENT OF THE LONG TERM PERFORMANCE OF RUBBER BRIDGE BEARINGS FOR USE IN HIGHWAY BRIDGES - REMOVAL AND TESTING PROJECT. REPORT 1: BRIDGE BEARING PADS FROM COWBRIDGE BYPASS

Two plain (unbonded) natural rubber bearing pads were removed from the Cowbridge Bypass in 1981 after about 15 years in service. The bridge bearing pads appear to have been formulated to BS 1154 of 1952 and meet the requirements of that specification. They contain no wax or chemical antiozonant. Apart from ozone resistance and tensile strength, the pads also satisfy the requirements of BS 5400. Despite the above the exposed edges of the pads show no evidence of ozone cracking. At depths of up to 1 to 2 mm from parts of the exposed edge the oxygen levels attributed to ingress of atmospheric oxygen is 1 - 1 1/2% which is consistent with moderate degradation. Elsewhere, and including parts within 1 to 2 mm of the exposed edge, oxygen levels do not differ significantly from freshly vulcanized rubber. The antioxidant flectol h is present at 2.5 parts throughout the portions of both pads analysed. Hardness varies from 70-75 irhd over (and through) the pads, and to this is attributed the 11% difference in shear modulus between the two pads. In the as received condition there was about a 2 mm variation in thickness across the pads. The lower face was relatively smooth and flat; the upper face tended to be proud over the central region. The effect of this variation in permanent set on the test data is not readily assessed. Some small amount of slip appears to have occurred at some edges of the pads. It is unlikely that the load-deformation characteristics in service would have been unduly affected by this. (TRRL)

• Corporate Authors:

  Malaysian Rubber Producers' Research Association

  Brickendonbury, Hertfordshire,   England 
• Authors:
  • Lindley, P B
• Publication Date: 1982-7-23

Media Info

• Features: Figures; Tables;
• Pagination: 12 p.

Subject/Index Terms

• TRT Terms: Antioxidants; Bridge bearing pads; Bridge bearings; Deformation; Deterioration; Loads; Motion; Oxidation; Oxygen; Ozone; Performance; Rubber; Shear strength; Tension; Tests; Thickness
• Uncontrolled Terms: Degradation; Tensile stress
• Geographic Terms: United Kingdom
• Old TRIS Terms: Resistance
• ITRD Terms: 3415: Bearing (bridge); 5595: Deformation; 5255: Deterioration; 5567: Load; 5483: Movement; 7157: Oxidation; 7108: Oxygen; 7494: Rubber; 5531: Shear; 6255: Test; 5933: Thickness; 8119: United Kingdom
• Subject Areas: Bridges and other structures; Design; Highways; I24: Design of Bridges and Retaining Walls;

Filing Info

• Accession Number: 00370301
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• Report/Paper Numbers: Monograph
• Files: ITRD, TRIS
• Created Date: Feb 28 1983 12:00AM