Effect of curing temperature and period on enzymatic induced calcite precipitation process for sustainable soil improvement

Abstract

Enzymatic induced calcite precipitation (EICP) is a novel, innovative, sustainable and environmentally friendly technique for soil improvement. EICP utilizes extracted free urease enzyme to induce calcite precipitation. Being enzymatic reaction, EICP process is susceptible to variation in pH, temperature, concentrations of reactants and urease enzyme content. This research studied the effect of curing temperature, ranging from 30 to 60°C on the shear strength and calcium carbonate content (CCC) of EICP treated residual soils cured at 3, 7, and 14 days. Based on the experimental results obtained, it was found that curing temperature has tremendous effect on the shear strength and CCC, while curing period has insignificant influence on the strength and CCC of EICP treated residual soils. The results have shown that at 3 days curing period, maximum shear strengths of 763.29 and 876.92 kPa were determined at optimum curing temperature of 50oC when the residual soil was treated with 0.50 and 1.00 M, respectively. It was also found that the increased in shear strength and CCC of EICP treated residual soil was insignificant beyond 3 days curing period. The UCS values of 0.50 M treated samples cured under 50°C at 3, 7, and 14 days were 763.29, 781.15, and 790.99 kPa. In summary, curing temperature has tremendous effect on the shear strength and CCC of EICP treated residual soil and maximum efficiency of the EICP process could be attained at 50°C.