Effect of biocementation on the engineering properties of sand soils under different flow rates and treatment durations

In recent years, biocementation has emerged as a promising technology for soil improvement research. This eco-friendly and sustainable approach involves a range of biochemical treatments, and its effectiveness is influenced by various factors. In this study, the effects of soil grain sizes, treatment duration (3, 6, and 11 days) and cementation solution flow rate (0.266, 0.400, and 0.666 ml/sec) on the engineering properties of treated soil were investigated by using the biocementation technique. The strength, calcite percentages, permeability, morphological appearance and structures of the treated sand soils were examined. According to the results, for each soil, different results were obtained with the same flow rates and treatment times. The highest strength value determined as 2406 kPa in the 11 day treatment at 0.400 ml/sec flow rate for smaller particle size of soil whereas the highest strength value obtained as 1504 kPa in the 11 day treatment at 0.266 ml/sec flow rate for larger particle size of soil. Higher strength results were obtained at lower flow rates (0.266 ml/sec) in samples with large grain diameter while strength results could not be obtained from it after treatment at higher flow rates (0.400, 0.666 ml/sec). In addition, strength results were obtained with a smaller grain diameter at a high flow rate (0.666 ml/sec), but decreased from 1599 to 1190 kPa when raising the treatment duration from 3 to 11 days. The flow rate and treatment duration in studies should therefore be chosen according to the particle size distribution of the soil. © 2023, The Author(s) under exclusive licence to Iranian Society of Environmentalists (IRSEN) and Science and Research Branch, Islamic Azad University.