Abstract: Microbial-based self-repair of concrete cracking is a research hotspot in China and abroad in recent years. This study uses Bacillus Coriolis as the mineralizing microorganism and lactic acid calcium as a nutrient to study the effect of mineralizing microorganisms on the early compressive performance and microscopic pore characteristics of hydraulic concrete. We conduct compressive tests on the concrete with different microbial concentrations, and observe the variation trends in compressive strength. Nitrogen adsorption and scanning electron microscopy are adopted to study microscopically the effects of microbes on pore water, microporous structure, and micro morphology of industrial concrete. The test results show that the compressive strength can be significantly improved by mixing microorganisms; with the increase in microorganism concentration, it shows a trend of increasing first sharply and then mildly. It has a peak at the microorganism concentration of 9.8×107cells/cm3 after an increase in the 28 d strength by 13.1%. Our microscopic observations reveal the microbes can effectively elevate the density and its uniformity of hydraulic concrete cement paste and improve the internal structure, thus significantly raising the compressive strength of the concrete mixed with mineralized microorganisms.

Key words: hydraulic concrete, mineralized microorganisms, compressive strength, pore structure, micro characteristics