Mechanical Characteristics of Straw Fiber–Enhanced MICP-Treated Silt

Straw fibers were introduced to enhance the deformation resistance and toughness of soil strengthened by microbially induced calcite precipitation (MICP). The influences of straw fiber content and length on the compressive strength, tensile strength, and disintegration resistance of soil reinforced by MICP were studied. The results indicate that straw fibers effectively enhanced the strength and disintegration resistance of MICP-treated samples. The compressive and tensile strengths increased with increasing fiber content and length, and disintegration resistance also improved with increased fiber content and length. When the fiber length was 2 cm and the content was 0.8%, the compressive strength increased by 77.4%, the tensile strength increased to 2.74 times that of the control samples, and the disintegration coefficient decreased by 43% compared to the control samples. The cementing properties of calcium carbonate (CaCO3) enhanced the attraction between adjacent soil particles, resulting in their accumulation around the fibers. As a result, the fibers became encased within a matrix of CaCO3 precipitates and soil particles, resembling anchor heads firmly embedded in the soil matrix, making the fibers difficult to extract and further improved the soil strength. Moreover, the bridging effect of the fibers restricted the expansion of failure surfaces, thereby deformation resistance of the sample was enhanced.