Influences of calcium source and curing method on uniformity and strength of sandy loess treated by MICP

Sandy loess has high sand content and a loose porous structure, and its mechanical properties are different from those of typical silty loess and sand. In order to study the effect of calcium source and curing method on the curing effect of microbially induced carbonate precipitation (MICP) technique in the treatment of sandy loess, small-scale tests were carried out by the soaking method and the perfusion method with three calcium sources (calcium chloride, calcium acetate and calcium lactate) respectively. The calcium carbonate content, calcium carbonate distribution uniformity and unconfined compressive strength (UCS) of the solidified samples were used as evaluation indexes for comparative analysis. The results show that the uniformity of the solidified samples is better when calcium acetate is used as the calcium source. The calcium carbonate content and UCS of the solidified samples are greater when calcium lactate is used as the calcium source in the early stage of treatment, but with the increase of treatment time, the strength of the solidified samples with calcium chloride as the calcium source is greater. Compared with the soaking method, the perfusion method can effectively improve the poor seepage of calcium lactate, and the curing effect is better than that of calcium chloride and calcium acetate when calcium lactate is used as the calcium source. The calcium carbonate distribution of the solidified sample by the perfusion method is more uniform and the strength is greater.