Small-strain shear modulus of weakly cemeneted sand using bender elements

The study explores the variation of small-strain shear stiffness, G0, with stress-level and void ratio for both uncemented and cemented sand specimens of Ticino river silica sand (TS) by performing Bender Element (BE) tests in triaxial apparatus. The process of cementation was artificially induced by adopting a proprietary chemical treatment (“Silica gel”),which is a non-particulate, non-toxic solution of low viscosity. Consistent with previous studies, the G0 of uncemented sands was dominantly affected by the void ratio and mean effective stress. In the case of cemented sand specimens, test results highlighted the critical role that even light cementation can play on the dynamic performance of soils: In particular, low levels of cementation lead to 20% higher dynamic shear modulus than the uncemented one regardless of effective confining stress, essentially due to an increase in stiffness coefficient. The increase in maximum dynamic shear modulus, G0, produced by chemical grouting was found to be equivalent to the effect of a densification of uncemented sand of around 75% density index.