The influence of variations in salinity levels on the biocementing process on soil improvement of liquefaction potential

This article presents an innovative method of soil improvement cementing to increase the shearing strength of very loose sand with 10% relative density (Dr) in saline conditions. Salt in saline soils destroys the stability of stable soils. In contrast, the salt content reduces the level of homogenization of unstable soils, causes technical problems in calcareous soils, and affects their stability, especially if the salt content is more than 3.0%. The variations in salinity levels can determine the optimal percentage of salt levels in the stabilized soil. The application of biocementation to saline soil can drastically increase the shear strength of soil in soil with potential liquefaction in coastal areas due to earthquakes. Calcium carbonate deposition (MICP) in the microbial-induced biocementing process is a new method that utilizes the metabolic processes of microorganisms in this study using Bacillus sp. In the MICP process, microbes need Ca2+ ions obtained from fly ash, which can produce SiO2 and CaO to produce CaCO3 for binding between particles. Soil improvement was carried out by combining initial soil, fly ash, mycobacteria, and variations in salinity obtained from NaCl with varying percentages of 0%, 1%, 2%, and 3,4% after testing at curing times 7, 14, 21, and 28 days. The research samples from the UCS and direct shear tests showed that the shear and UC strength that were treated increased. The highest increase in shear strength was at 3,4% salinity at 28 days of 80.9°. CaCO3 production resulting from the binding between particles in the biocementing reaction can be seen from the results of SEM tests. Soil improvement using biocementing in this study resulted in an effective increase in the strength of loose sand soil in salinity condition.