The Impact of Biocalcification on Strength of Semi-Arid Zone Sand of Northeastern Nigeria

Efforts to minimize energy loss during soil improvements have resulted in the emergence of environmentally friendly and sustainable biological process, termed biocalcificaion (or microbial induced calcite precipitation, MICP). Biocalcification technique was applied on a loose and wind-susceptible semi-arid zone soil of low strength for fugitive dust control process. The soil was treated with varying non-pathogenic urease positive Bacillus megaterium (B. megaterium) suspension densities (i.e., 1.5 x 10(8), 6.0 x 10(8), 1.2 x 10(9), 1.8 x 10(9), and 2.4 x 10(9) cells/ml) and cementation reagent concentrations (i.e., 0.25, 0.5, 0.75, and 1 M) using different treatment cycles of 1, 2, and 3 and at a mix ratio of 50:50 (bacteria:cementation). Peak unconfined compressive strength (UCS) value of 453 kN/m(2) was obtained for soil compacted with standard Proctor energy and treated (in three cycles) with B. megaterium suspension density of 1.8 x 10(9) cells/ml and 1 M cementation reagent. The urease activity and calcite content increased with higher bacteria/cementation contents that indicates the potential of the biocalcification technique for the improvement of the semi-arid zone soil considered in the study.