Tensile Strength Enhancement of Soils Using Fiber and Biocementation: Effects of Treatment Method and Biotreated Fibers

Abstract The tensile behavior of soil is crucial for geotechnical design because tensile cracking can initiate soil erosion, slope failures, and structural failure, including embankments, dams, and retaining walls. These failures affect structural integrity and lead to environmental deterioration by enhancing soil permeability and promoting the movement of sediments and pollutants. Consequently, there is an increasing demand for sustainable techniques to improve soil tensile strength and provide long-term stability and sustainability. Based on this, in the current study, direct tensile tests were performed on a series of biocemented soil, fiber-reinforced soil, biocemented fiber–reinforced soil, and fiber-reinforced biocemented soil. The study was conducted using two different soils, fibers (jute and polypropylene), and treatment processes [microbial-induced calcite precipitation (MICP) and enzyme-induced calcite precipitation (EICP)]. Three different methods were adopted for biotreatment, namely, the direct mixing method (DMM), biotreated fiber mixing method (BFMM), and mixing-percolation method (MPM). The novel method of biotreatment of fibers was explored in this study. The tensile test results showed that the combined use of biocementation and fiber reinforcement significantly increased the peak tensile strength and ductility of soil. The increase in tensile strength was higher for specimens subjected to the MICP process than for those treated with the EICP process. Further, biotreatment of fiber offers a more practical and consistent approach for soil stabilization by improving the tensile strength of the soil.