Stiffness of a biocemented sand at small strains

This paper presents the triaxial testing results of a study in which biocementation processes were employed to observe the behaviour at small strains of sand matrix. Biocementation was achieved using the microorganism Sporosarcina pasteurii, an aerobic bacteria growth in natural soil deposits. The microbes were introduced to the sand specimens in a liquid growth medium with three different amounts of urea and dissolved calcium sources. Subsequent cementation treatments were passed through the specimen under confining pressure. The results were assessed by local strain measurements using LVDTs. A series of undrained compression triaxial tests indicate that at small strain levels the observed stiffness-strain behaviour of biocemented sand specimens appeared to be significantly high for all three treatment levels. The response of biocemented sands was found to be similar to that of calcite and lime cemented specimens, which represent conventional cementing agents. Scanning electron microscopy pictures and energy dispersive X-ray were taken to verify the formation of cement at three different concentrations.