Liquefaction resistance of Fraser River sand improved by a microbially-induced cementation

Microbially induced calcite precipitation (MICP) harnesses the natural metabolic action of bacteria to induce the precipitation of calcium carbonate and alter soil engineering properties. This paper presents the results of using MICP to improve the cyclic resistance of Fraser River sand specimens. The formation of calcite cementation among sand particles is confirmed using scanning electron microscopic images and X-ray compositional analysis of cemented sand clusters. The results show that the velocity of a shear wave (V-S) traveling through the specimen starts to increase just as the calcium solution is introduced into each specimen. Liquefaction resistance of sand samples is subsequently measured in a series of cyclic direct simple shear tests. MICP-treated samples exhibit cyclic resistances of up to 67% higher than those of the untreated sand. Post-liquefaction volumetric strain and changes in cyclic resistance in a repeated cyclic loading are also assessed and compared for the original and the treated sand specimens.