Strength and dilatancy of sand before and after stabilisation with colloidal-silica gel

To evaluate the effect of stabilisation by using a colloidal silica aqueous gel on the subsequent behaviour of sand, the dilatancy and peak and ultimate strength characteristics of M31 sand were investigated before and after stabilisation. Triaxial compression tests were performed in drained and undrained mode, at effective stresses ranging from 100 to 6000 kPa. Important changes in the sand's mechanical behaviour were observed after stabilisation, including a significant increase in stress ratio and dilatancy rate at peak and a relocation of the treated sand's critical state line in the e–p′ plane, substantially above that manifested by the untreated sand; however, the two lines converged at high stresses. The results confirm a state-dependent behaviour for the sand that is not applicable to the treated sand, which exhibits predominantly stress-dependent behaviour. A modified state parameter was used to normalise the treated sand's behaviour at peak failure.