Consolidated Undrained Behaviour of Cemented Sand–Silt Mixtures

Abstract

Loose deposits of silty sand, which are more prone to failure, on cementation show resistance against it. The presence of fines in sand changes the stress–strain–strength behaviour of sand and cemented sands. In the present study, sand has been replaced with non-plastic silt by varying percentage of 10%, 20%, 30% and 40% by dry weight of sand. Portland pozzolana cement of 2.5% by dry weight of sand was used as cementing agent with curing period of 7 days. The triaxial behaviour of cemented sand–silt mixture under consolidated undrained condition by varying silt content for confining pressures of 100 kPa, 200 kPa and 300 kPa is studied. The important observations made from laboratory investigations are given below. For a confining pressure of 100 kPa, the sample with 20% silt shows higher failure deviatoric stress than 10% silt, and the sample with 30% and 40% silt shows comparatively lesser failure deviatoric stress than the sample with 20% silt. The same pattern is followed for confining pressures of 200 kPa and 300 kPa. For confining pressure of 100 kPa, the failure axial strain is higher for samples with 30% silt content compared to 10% and 20% silt content. But the samples with 40% silt show comparatively lesser failure axial strain than 30% silt content. The same pattern is followed for confining pressure of 200 kPa and 300 kPa as discussed before. For silt content of 10%, increasing the confining pressure up to 200 kPa increases failure axial strain and at confining pressure of 300 kPa shows comparatively lesser failure axial strain than 200 kPa. This variation in failure axial strain is observed in almost all the silt contents studied. Pore water pressure developed in all the silt content studied shows initial positive pore water pressure and then changes to negative pore pressure, but the magnitude of PWP developed decreases with increase in silt content.