Influences of temperatures on MICP-treated soils

A series of aqueous tests, one-dimesion sand column trials and bacterial activity tests using the ureolytic bacteria ATCC11859 are conducted to investigate the influences of temperatures (10℃, 20℃ and 30℃) on the microbially induced carbonate precipitation (MICP). The results show that in the aqueous tests, the effect of temperatures on the MICP is related to the reaction time; at the early stage, the consumption of calcium ion is much more at the higher temperature environment; after a period of time of the reaction, the consumption of calcium ion is much more at the lower temperature. In the sand column trials, the unconfined compressive strength of the sand samples after consolidation at the lower temperature is greater than that at the higher one, and the results of the calcium carbonate content of the samples show that the content of calcium carbonate in the sand columns is much lower at the higher temperature than that at the lower one. The stress-strain relationship of the unconfined compression tests shows that the sand column treated by MICP in the lower temperature environment can produce a larger deformation when the peak strength is reached. The bacterial activity tests under different temperatures show that the rapid decline in bacterial activity is the reason why the final amount of calcium carbonate is lower at the higher temperature.