Abstract: The microbial induced calcium carbonate precipitation (MICP) is one of the types of research focuses in the field of geotechnical engineering, but its cumbersome treatment steps and low curing efficiency limit its further applications in the curing coral sands. To reduce the number of processing times and to improve the efficiency of the curing coral sands, different concentrations of the aluminum ionic flocculant (AlCl³·6H₂O) were added to the cementing solution, and the effects of the aluminum ionic flocculant on the curing speed and curing effect of the MICP were investigated through experiments. The experimental results showed that: after 6 cycles of the grouting treatment, the unconfined compressive strength of the sand column reached 2.8～7.2 times of that of the control group, and the unconfined compressive strength could reach up to 2123 kPa; the introduction of the aluminum ionic flocculant could effectively induce the calcium carbonate crystals generated in the coral sand column to be transformed from unstable spherical chalcocite type to stable calcite type, which significantly enhanced the curing efficiency of the MICP. The results verified the feasibility of the microbial curing technology with aluminum ionic flocculant in the calcareous sand reinforcement scheme for island reefs.

Key words: Microbial Induced Calcium Carbonate Precipitation, Coral Sand, Aluminum Ion Flocculant, Unconfined Compressive Strength, Curing Mechanism