Permeability and Mechanical Properties of Fine Sand Improved by Microbial Carbonate Precipitation

There is a ground improvement technology that utilizes carbonate calcium precipitated from carbon dioxide generated by microbial metabolism and calcium sources in pore of soil. It is known that the mechanical properties of improved grounds correlate with the amount of calcium carbonate precipitation. However, the relationship between mechanical properties and permeability has yet to be clarified. In this study, we estimated the apparent coefficient of permeability from the injection speed of nutrient and performed triaxial compression tests (CD condition) on specimens, aiming to assess the relationship between the mechanical properties and permeability of Toyoura sand, which is compacted by microbial metabolism. Through the study, we confirmed that the Young’s modulus and peak strength tend to increase as a function of the amount of precipitated calcium carbonate, with little change in the coefficient of permeability.