Use of digital image technique to study leachate penetration in biocemented residual soil

Abstract Recently, biocementation has become a trend of soil improvement. Nevertheless, few studies were conducted in its application to improve engineering properties of fine-grained soil. In this study, digital image technique (DIT) was employed to determine the effect of biocementation via enzymatic induced calcium carbonate precipitation (EICP) technique on the leachate penetration pattern and medium-term hydraulic conductivity of the compacted residual soil made from fine-grained soil. The findings have shown that the of leachate penetration pattern and hydraulic conductivities of the EICP treated soils were considerably affected by the formation of biocementation or CaCO3 precipitation. It was found that the rate of leachate penetration was faster within the first 14 days of the test. It was also determined that at the end of 28 days, the amount of leachate penetrated the untreated soil, 0.50 M, and 1.0 M EICP treated soils were 14.16 mm, 10.08 mm, and 6.03 mm, respectively. The results have shown that EICP treatment resulted in the reduction of hydraulic conductivity by 28. 28.83% and 41.33% in 0.50 M and 1.00 M treated soils, respectively.