EVALUATION OF STRENGTH PROPERTIES OF BACILLUS PUMILUS TREATED LATERITIC SOIL IN MICROBIAL INDUCED CALCITE PRECIPITATION APPLICATION
Keywords:
Bacillus pumilus, Lateritic soil, Microbial-induced calcite precipitate, Unconfined compressive strength, Compactive effort, Curing timeAbstract
Unconfined compressive strength (UCS) of soil is usually affected by curing periods (in days) and compactive effort. To evaluate the strength properties of Bacillus pumilus (B. pumilus) treated lateritic soil in microbial induced calcite precipitate (MICP) application, the UCS of B. pumilus microbial induced calcite precipitate treated lateritic soil were carried out at different curing periods and different compactive effort. Lateritic soil was treated with stepped densities of B. pumilus suspensions densities of 0 /ml (for natural soil), 1.5 x 108 /ml, 6.0 x 108 /ml, 12.0 x 108 /ml, 18.0 x 108 /ml and 24.0 x 108 /ml, respectively and compacted with British Standard Light (BSL), West African Standard (WAS) and British Standard Heavy (BSH) energies. The treated specimens were cured for 7, 14 and 28 days. Specimens of lateritic soil treated with different mix ratios of B. pumilus suspension density of 1.20 x 109 cells/ml – cementation reagent using 25% Bp – 75% Cr, 50% Bp – 50% Cr and 75% Bp – 25% Cr mix ratio gave peak UCS values of 2, 414 kN/m2, 3,072 kN/m2 and 3,144 kN/m2, respectively, when specimens were compacted with BSH energy. Higher soil strength gains were recorded for the different curing periods and all compactive effort considered.