Shear resistance of bitumen-coated piles in sand

The shear resistance of bitumen-coated piles in sand is studied with interface shear tests in a modified direct shear apparatus and pull-out tests on model piles. The interface shear tests are conducted to study the effect of pile material, thickness of coat, normal stress, and rate of shear on pile shear resistance. The shear resistance of bitumen-coated samples and sand is found to be independent of the roughness of the pile material. The bitumen coating reduced shear resistance by more than 90%. Shear resistance reduces with increase in the thickness of coat for a given normal stress and is found to be influenced by the rate of shear. The results of pull-out tests conducted to compare the shear behaviour of coated and uncoated model aluminium pipe piles driven in sand are also presented. The pull-out and interface shear tests show a similar response to increase in coat thickness and normal stress. The shear resistance of bitumen-coated piles is found to increase only marginally with the density of the soil. Scale effects in the model tests are also discussed.