LIQUEFACTION MITIGATION EFFICIENCY OF SAND IMPROVED WITH CALCIUM CARBONATE PRECIPITATED UNDER VARIOUS DEGREES OF SATURATION

Abstract

 It is pointed out that the shear strength of cemented soil improved with calcium carbonate (CaCO₃) crystal is enhanced by decrease in saturation degree during precipitation. In this study, improvement efficiency of liquefaction resistance enhanced through controlling saturation degree (from 20 to 100%) and CaCO₃ content (from 0 to 1%) was investigated by undrained cyclic triaxial tests for coarse and fine sand specimens. Enzymatically Mediated Calcite Precipitation (EMCP) technique was employed to precipitate CaCO₃. SEM-EDX was utilized to observe calcium carbonate crystal on the sand grain surface and to identify the crystal. It was found that, in EMCP with controlling saturation degree during precipitation, high efficiency in liquefaction mitigation was provided to finer sand including larger crystal.