Geotechnical Engineering Properties of Soils Solidified by Microbially Induced CaCO₃ Precipitation (MICP)

Table 1

Previous studies on different cementation solution concentrations.

Reference	Bacteria	Cementation solution concentration	Conclusion
[41]	B. megaterium	0.25, 0.5, 1.0 mol/L urea-calcium chloride	The shear strength of the specimens treated with 0.25 mol/L cementation reagent improved by 26–57%, and the hydraulic conductivity reduction ranged from 16 to 73%
[48]	S. pasteurii	0.25, 0.5, 1.0 mol/L urea; 0.25, 0.5, 1.0, 2.0 mol/L calcium chloride	The UCS of sand column treated with 1 mol/L urea and CaCl2 solution is the largest
[49]	S. pasteurii	2.5, 25, 250 mM Ca^2+; 333, 666 mM urea	Increasing urea and Ca^2+ concentrations increase the amount of carbonate precipitated. The CaCO3 precipitated depend more on the Ca^2+ concentration than the amount of urea
[50]	S. pasteurii	0.5, 1.0, 1.5 mol/L urea and calcium chloride, concentration ratio: 1 : 1, 1 : 2, and 2 : 1	The CaCO3 content and peak strength of the samples increase with the increasing of the cementation solution concentration, with the maximum being at concentration ratio 2 : 1
[51]	S. pasteurii	0.25, 0.75, 1, 2 mol/L urea and calcium chloride	An increase in urea and calcium concentrations increased the CaCO3 precipitation. The greatest amount of CaCO3 was achieved at the condition of 1 mol/L urea and 2 mol/L calcium chloride