Effect of microbial mineralization on red clay

The technology of microbial mineralization was applied to the modification of red clay, in which the metabolites of bacillus pasteurii were used. Routine physical index tests were carried out on the red clay samples to analyze the changes of water content, density, specific gravity, porosity ratio and particle size by the modification. The shear strength of soil was determined by triaxial undrained shear tests. The microstructure of red clay was observed by SEM. The results show that the Bacillus pasteurii can induce the precipitation and cementation of calcium carbonate to fill voids of red clay effectively, and the soil sample was the best after 10 days of curing with constant temperature. With the addition of bacteria and the occurrence of microbial mineralization, the physical properties of the red clay changed significantly, and the internal friction angle and cohesion of the sample increased. Analysis of SEM images shows that calcium carbonate crystals were generated in the red clay sample which filled in the pores of the soil and strengthen the connection between soil particles.