Laboratory improvement of liquefiable sand by colloidal silica and weak cementation

A laboratory study was undertaken on the improvement of the cyclic response of liquefiable sand by means of two treatment techniques - passive stabilisation and weak cementation. Colloidal silica (CS) solution at concentrations of 6 and 10% and Portland cement added in the amount of 1 and 3% by weight of dry soil were used as stabilising agents for the implementation of passive stabilisation and weak cementation, respectively. The results of cyclic triaxial tests on sand treated using the above two techniques, as well as on untreated sand for comparison, are presented. Unconfined compressive and tensile strength tests on improved sands, which served as index tests, are also presented. The experimental results show significant improvement of the cyclic response of the treated sands and thus indicate the effectiveness of both techniques. Nevertheless, it was found that cementation, even at small cement contents of 1%, resulted in an improvement equivalent to or even greater than that induced by passive stabilisation under the CS concentration studied.