Development of a Flexible Mold for Bio-Mediated Soil Materials

Abstract

Microbial induced calcium carbonate precipitation (MICP) has attracted attention as a sustainable means of soil improvement in recent years. Sporosarcina pasteurii is widely used in the MICP process for laboratory experiments due to its highly active urease enzyme. Although the process can bond around loose sand and improve the engineering properties of sand, it is difficult for cementation media (Urea – CaCl2 solution) to fully contact and react with the bacteria inside soil sample through pores of sand, and the calcium carbonate precipitation formed on the soil sample surface always clogs the pores during the MICP process. In this study, a full contact flexible mold was developed for a more uniform calcium carbonate precipitation in the soil sample during the MICP process. The new sample preparation mold provides supports for the bacteria to grow through fully contact cementation media and induce the calcium carbonate precipitated homogeneously within the pores of the sand. The development of the full contact flexible mold was described. Different size specimens were prepared using the full contact flexible mold to evaluate engineering properties improved by MICP treated soil. Direct shear test and unconfined compressive strength results showed that the improvement of MICP treated soil with full contact flexible mold is one order of magnitude higher than that of the typical sample preparation method.