BITUMEN SELECTION FOR REDUCTION OF DOWNDRAG ON PILES

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