Bitumen Selection for Reduction of Downdrag on Piles

Abstract

Bitumen has been shown to reduce significantly the downdrag load on piles. The problem is to know how to choose the right bitumen for the job. The right bitumen must not deform excessively under gravity stresses during the storage period, must not deform excessively under dynamic stresses due to pile driving, must offer little shearing resistance and therefore downdrag during the soil settlement process, and must not let the soil particles penetrate excessively into the coating. Rational design approaches are developed for each of the four criteria on the basis of the fundamental behavior of bitumen, full-scale downdrag tests on 15 piles at a Northern and Southern site, and a series of laboratory tests. Guidelines are presented for the bitumen selection process and tips are given for the field application of the bitumen coating.