Microbial modified baslt fiber synergistic solidification of Pisha sandstone: Study on mechanical properties and...

Aiming at the soil erosion problem in the Pisha sandstone area of Ordos, Inner Mongolia, China, a novel reinforcement technology coupling Microbially Induced Calcite Precipitation (MICP) with modified basalt fibers is proposed based on basalt fibers treated by a new-type surface modification process. The present study investigates how fiber content affects the calcium carbonate conversion and mechanical properties of MICP-treated samples, and analyses the fiber surface modification mechanism. To this end, modified basalt fiber-Pisha sandstone composites are tested. The findings indicate that for cylindrical specimens measuring 50 × 100 mm, the optimal dosage of modified basalt fibers is 0.4%. In comparison with the fiber-free control group, this results in an increase in unconfined compressive strength of 2.88 times to 2.75 MPa and an increase in calcium carbonate production of up to 1.87 times. The modification has been shown to enhance fiber surface roughness, thereby providing abundant sites for microbial attachment. This has been shown to enhance microbe-fiber interaction, encourage colonization and biofilm formation in the sandstone, and reduce microbial loss. The modification has been shown to enhance urease efficiency by improving microbial attachment and elevating local ion concentrations. In addition, the roughened fiber surface acts as a nucleation site for CaCO₃, lowering the energy barrier for crystallization. This dual effect has been shown to significantly increase both the yield and uniformity of calcite precipitation, thereby providing essential material support for soil reinforcement. The dosage of fiber has been demonstrated to exert a threshold effect on soil toughness: low dosages yield limited improvement; the optimal dosage significantly enhances energy absorption; excessive fibers cause agglomeration and stress concentration, reducing toughness. The precise control of fiber dosage is paramount to ensure optimal performance. The interaction between MICP and modified basalt fibers has been shown to exhibit a synergistic effect, whereby the precipitated calcium carbonate enhances the formation of granular bonds, thereby firmly anchoring fibers to particles. This, in turn, serves to reinforce the constraint effect within the fiber network. The present study elucidates the synergistic reinforcement mechanism of MICP and modified basalt fibers, thus offering a novel technical approach to enhance the solidification strength and calcium carbonate conversion rate of Pisha sandstone. Provides a green, efficient and sustainable solution for ecological restoration and engineering soil stabilization in Pisha sandstone areas.