Evaluating the Applicability of Biostimulated Calcium Carbonate Precipitation to Stabilize Clayey Soils

Abstract

Clayey soils with medium to high plasticity are prevalent in several parts of the world, causing billions of dollars in damage annually to various civil infrastructures. Several groundimprovement-techniques were employed to counteract this issue. However, these methods are impractical in certain situations and unsustainable in others due to their economic and environmental impacts. Microbial Induced Calcite Precipitation (MICP) could provide a more sustainable alternative. Researchers have successfully used MICP to alter specific geotechnical properties of the sands and silts. This research investigates the applicability of MICP via biostimulation to treat clayey soils with low to high plasticity. The goal is to determine the viability of this technique to alter the engineering behavior of clayey soils, especially given the low permeability of these soils. For this purpose, four soils were selected from four different locations in Idaho and Montana. The soils were selected such that their plasticity varied from low to high to study the effect of plasticity index on the effectiveness of MICP treatments. In addition to the four soils, three additional artificial mixes were studied to study the effect of clay content on MICP effectiveness. Both macro and micro scale studies were conducted on untreated and biostimulated soils to observe strength gain, swelling reduction, calcium carbonate precipitation. The results show that MICP via biostimulation would be a promising method to treat problematic clayey soils.

Strength and Durability of Cement-Treated Lateritic Soil

“…A study by Islam et al [39] revealed that, in general, MICP increased the UCS of clay soil, but the enhancing rate of UCS was below the threshold for some subgrade soils. However, the authors [39] indicated that the UCS of clayey soil might be increased beyond the threshold using additional treatment cycles. The enzyme-induced calcium carbonate precipitation (EICP) technique requires the urease enzyme rather than bacteria.…”

“…For instance, biomaterials (bacteria and enzyme) [34] are utilized in bio-cementation techniques such as microbial-induced calcium carbonate precipitation (MICP) and enzyme-induced calcium carbonate precipitation (EICP) because of their "environmentally-friendly" features [35]. Microbially induced calcite precipitation (MICP) as a biomineralization method has been used for soil stabilization in previous studies [36][37][38][39]. A biochemical process occurs in the MICP method to improve soil properties.…”

“…In stabilizing sub-base material, the MICP method affects the environment 3.4 times more and is about 1.6 times costlier than the conventional cement stabilization method due to its high volume of chemical solution requirements [43]. A study by Islam et al [39] revealed that, in general, MICP increased the UCS of clay soil, but the enhancing rate of UCS was below the threshold for some subgrade soils. However, the authors [39] indicated that the UCS of clayey soil might be increased beyond the threshold using additional treatment cycles.…”

Effect of Scallop Powder Addition on MICP Treatment of Amorphous Peat

“…Few studies could extend the technique for stabilizing soft soils. For instance, Islam et al (2020) evaluated the effect of the clay content on MICP treatment. Their outcomes indicated that although the formation of calcium carbonate could marginally increase the unconfined compressive strength (UCS), the values attained after saturation were far below 50 KPa.…”

Improvement and Soil Consistency of Sand–Clay Mixtures Treated with Enzymatic-Induced Carbonate Precipitation

“…Therefore, the strength was contributed to by the cementing effect from clay soils and cementation homogeneity. The cementing effect from clay soils and better cementation homogeneity resulted in higher strengths than the results in [36,37].…”