Mechanical Behavior of MICP-Treated Sand under Different Confining Pressures

Microbially induced calcite precipitation (MICP) is a sustainable and naturally occurring biological process that harnesses the metabolism capabilities of bacteria to produce a cementation agent known as calcite (CaCO3). This study is to examine the effects of different reaction environments on the mechanical behaviors of MICP-treated sand. The mechanical behaviors will be evaluated through unconfined compression stress (UCS) experimenting with samples at 3, 7, and 14 days of curing in positive pressures at three different magnitudes (0, 50, and 100 kPa) or negative pressures at four different pressures (0, –5, –15, and –25 in-Hg). The results showed that the UCS of MICP-treated samples decreased with the increase of positive pressure. As for the samples with negative pressure, a better mechanical performance was observed when the negative pressure is –5 in-Hg. The SEM image clearly illustrated the change of CaCO3 crystal morphology under different treatment conditions.