2010 Volume 51 Issue 1 Pages 10-18
We have been performing fundamental laboratory tests in order to develop a novel conceptual grout, hereafter called biogrout. Hardened biogrout consists primarily of calcium carbonate or silica, typical cement elements in soil and rock. These compounds can fill the voids and cracks in soil and rock using microbial metabolism. This paper reports some test results for biogrout using calcium carbonate and discusses them. We performed a series of precipitation tests on calcium carbonate in test tubes using soil microorganisms sampled from various parts of Japan, examining the effect of temperature on the precipitation of calcium carbonate when testing. As a result, it was indicated that precipitation of calcium carbonate using soil microorganisms occurred at temperatures ranging from 5 to 35°C. Furthermore, we measured the number of soil microorganisms used in the tests and conducted gene analyses of them. The phases of soil microorganisms before testing were compared to those after testing by determining the number of living soil microorganisms, the highest relative frequency of soil microorganisms, and their attributive taxonomical groups. In consequence, it is possible that fungi such as the Penicillium and Aspergillus species frequently metabolized organic nutrition, and at the same time their number increased via their metabolism.
