Enhancing Strength of MICP-Treated Sand with Scrap of Activated Carbon-Fiber Felt

Microbial-induced calcium carbonate precipitation (MICP) technique takes advantage of the metabolic process of bacteria bonding soil particles together with an environmentally-friendly and sustainable manner. In this study, powder of activated carbon-fiber felt (ACFF) scrap was utilized together with MICP to improve soil strength, and six different ACFF ratios (0%, 0.2%, 0.6%, 1%, 1.4%, and 2% by weight) were adopted. Unconfined compressive strength (UCS) and splitting tensile strength (TS) tests were carried out for evaluating the effect of ACFF on the dry and saturated strength of MICP-treated sand. It was found that the bacterial immobilization extent increases in the presence of ACFF, subsequently resulting in a greater yield of calcium carbonate. UCS and TS are remarkably enhanced with a small quantity of ACFF, and softening degree caused by water can also be improved by ACFF. However, only strength rather than ductility could be enhanced by ACFF. On the whole, wasted ACFF scrap could be effectively reused in the MICP technique because of the better behavior of ACFF reinforced MICP-treated sand.