Enhancing the durability of coastal soil treated with fiber-reinforced microbial-induced calcite precipitation (MICP)

Microbial-induced calcite precipitation (MICP) has recently emerged as a sustainable, eco-friendly, potentially sound ground improvement technique. The durability of MICP-treated samples remains a major concern in this innovative method. This study examines the impact of three types of fiber reinforcements, namely carbon, basalt, and polypropylene, on the durability of biotreated samples of coastal sand. The fiber content used was 0.20%, 0.40%, and 0.60% of soil weight. A comprehensive biotreatment investigation was conducted using Sporosarcina pasteurii in a 0.5 molar cementation solution. The amount of calcite precipitation, scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to interpret biocementation. Biotreated samples were subjected to 5, 10, and 15 wetting-drying (WD) cycles under seawater conditions to evaluate the durability of the fiber-reinforced MICP-treated Indian coastal soil. Following WD testing, mass loss, unconfined compressive strength (UCS), split tensile strength (STS), and ultrasonic pulse velocity (UPV) were measured for different fiber-reinforced MICP-treated samples. The study revealed that the WD cyclic process affects the mechanical and physical characteristics of fiber-reinforced MICP-treated samples. The optimal fiber content for carbon, basalt, and polypropylene fibers was 0.40%, 0.40%, and 0.20%, respectively. Notably, the basalt fiber-reinforced sample with a fiber content of 0.40% exhibited minimal effects from the WD cycles, with only a 3.53% mass loss after 15 cycles. Overall, the results strongly support the durability of fiber reinforcement under WD conditions.