Evaluating the electrical resistivity of microbial-induced calcite precipitate-treated lateritic soil

Abstract

Organisms or chemicals introduced into soils for soil improvement tend to make such soil reactive and this may affect the parameters that are used to determine the engineering and other properties of the soil. In this study, the electrical resistivity of Bacillus pumilus microbial-induced calcite precipitate-treated lateritic soil at different compactive effort was evaluated; lateritic soil was treated with stepped densities of B. pumilus suspensions of 0/ml, 1.5 × 108/ml, 6.0 × 108/ml, 12 × 108/ml, 18 × 108/ml and 24 × 108/ml, respectively, and compacted with three compaction energies, namely British Standard Light (BSL), West African Standard (WAS) and British Standard Heavy. The treated soil samples were cured for 7, 28 and 56 days to also see the effect of the curing period on the resistivity of the treated lateritic soil. The resistivity test result shows an increase in resistivity value with an increase in B. pumilus suspension density and also with an increase in compactive energy. Though there is a marginal increase between BSL and WAS compactive effort. The peak resistivity value was obtained at 2.4 × 109 cells/ml of B. pumilus suspension density for all compactive effort considered. The effect of curing days indicates that beyond 28 days there is only a marginal increase in resistivity value because there is little or no increase in the resistivity values obtained.