Effect of Microorganism Sporosarcina pasteurii on the Hydration of Cement Paste.

Years of research have shown that the application of microorganisms increases the compressive strength of cement-based material when it is cured in a culture medium. Because the compressive strength is strongly affected by the hydration of cement paste, this research aimed to investigate the role of the microorganism Sporosarcina pasteurii in hydration of cement paste. The microorganism's role was investigated with and without the presence of a urea-CaCl2 culture medium (i.e., without curing the specimens in the culture medium). The results showed that S. pasteurii accelerated the early hydration of cement paste. The addition of the urea-CaCl2 culture medium also increased the speed of hydration. However, no clear evidence of microbially induced calcite precipitation appeared when the microorganisms were directly mixed with cement paste.