Microbially/CO2-derived CaCO3 cement and its microstructural and mechanical performance

Compared with the production of ordinary Portland cement (OPC) with large carbon emissions, biological carbon sequestration to prepare low-carbon cement can effectively decrease carbon dioxide (CO2) emissions, which can reduce the greenhouse effect, thereby reducing the frequency and intensity of climate disasters. Carbon-capturing bacteria (CCB) can capture atmospheric CO2 and convert it into bicarbonate ions, which can be combined with calcium ions to form CaCO3 cement that can partially replace OPC for dust control. This study compared the ability of two CCBs (Paenibacillus mucilaginosus and Streptomyces microflavus ) to capture CO2. The biomineralization efficiency of CaCO3 for P. mucilaginosus (39.34%) was much higher than that for S. microflavus (7.38%) in a Ca(NO3)2 solution in the concrete-curing room environment. The decomposition temperature of the CaCO3 crystals in DI was slightly higher than that of P. mucilaginosus and significantly higher than that of S. microflavus. When the spraying time was equal to three, 10% carbide sludge (CS) content was optimal according to the surface hardness (HD) of the consolidation layer of the sand samples. The CaCO3 mineralized by CCBs can be used to consolidate desert sand and dust in practical engineering applications.