Enhancing the Strength of Coastal Soil Through Fiber-Reinforced Microbial-Induced Calcite Precipitation (MICP)

Abstract

Coastal soil erosion is a critical global issue, threatening infrastructure, livelihoods, and ecosystems. Microbial-induced calcite precipitation (MICP) has emerged as a promising technology for ground improvement. The present study explores the impact of adding carbon, basalt, and polypropylene fibers on the mechanical properties of coastal soil treated with MICP. Fiber contents of 0.20, 0.40, and 0.60% by soil weight were used in this study. Samples, with an aspect ratio of 2:1, were subjected to biotreatment for 9 and 18 days. Mechanical properties were evaluated through unconfined compressive strength (UCS) and ultrasonic pulse velocity (UPV) tests. The calcite precipitation was assessed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The findings reveal that incorporating fibers into the MICP process significantly enhances the mechanical properties of coastal soil. The optimal fiber content obtained was 0.4% for carbon and basalt fibers and 0.2% for polypropylene. Among all samples, the basalt fiber-reinforced soil treated for 18 days exhibited the highest UCS, UPV, and calcite (CaCO3) content. In contrast, the non-reinforced samples treated for 9 days showed the lowest values across these parameters. SEM analysis showed the CaCO3 precipitates on soil grain, while EDS confirmed the chemical composition, demonstrating successful biocementation. Overall, the study underscores the potential of fiber-reinforced MICP as an effective and sustainable solution for enhancing coastal soil stability. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.