Effect of aluminum chloride concentration on curing effect of MICP under different calcium source conditions

Both calcium source and admixture have an impact on the reinforcement effect of microbial induced calcium carbonate precipitation (MICP). In order to explore the effects of different concentrations of the admixture (AlCl₃·6H₂O) and calcium sources on the curing effect of MICP, the sand column test and aqueous solution test were carried out, and different concentrations of AlCl₃·6H₂O were added to the cementing solution for perfusion test, and the unconfined compressive strength (UCS) and calcium carbonate content after reinforcement were measured. The MICP reinforcement effects of calcium chloride and calcium acetate were analyzed, and the improvement of MICP reinforcement effect under different concentrations of AlCl₃·6H₂O for the two calcium sources was analyzed. The effect of aluminum ions on the composition and morphology of calcium carbonate was analyzed with SEM. The results showed that calcium acetate as a calcium source had a better curing effect. After the addition of aluminum ions, the strength optimization effect of calcium chloride as a calcium source was more obvious. Among them, the concentration of AlCl₃· 6H₂O at 6 mmol/L was the optimal concentration, which was conducive to reduce the number of perfusions, saving raw materials and reducing economic costs. Aluminum ions contribute to the formation of calcium carbonate crystals, enhance the adsorption of sand particles, and improve the curing strength. The concentration of aluminum chloride has a significant effect on the curing effect of MICP with different calcium sources, which is of great significance for engineering practice.