Contribution summary.

The integration of palm fiber with Microbially Induced Calcite Precipitation (MICP) technology offers a sustainable and bio-based approach to enhance the mechanical performance and durability of sandy soils, particularly under freeze-thaw conditions. In this study, a systematic experimental investigation examines the effects of varying palm fiber contents (0%−0.30%) on the bearing capacity, crust thickness, calcium carbonate deposition, and freeze-thaw resistance of MICP-treated sand. Results indicate that mechanical performance improves with increasing fiber content, peaking at 0.15%, beyond which the benefits diminish due to fiber agglomeration. At the optimal dosage, the bearing capacity increases by 24%, crust thickness by 70.5%, and calcium carbonate content reaches 16.8% compared to fiber-free MICP samples. Freeze-thaw tests demonstrate higher mass and strength retention, indicating improved durability. Microstructural analyses using SEM, XRD, EDS, and FTIR reveal enhanced microbial attachment and uniform CaCO₃ precipitation along fiber-sand interfaces, which strengthens matrix cohesion. These findings uncover a hybrid bio-mechanical reinforcement mechanism and highlight the trade-offs between fiber dosage and pore connectivity. This study provides novel insights into fiber-assisted biomineralization and offers a viable pathway for environmentally friendly soil reinforcement. Furthermore, potential directions such as predictive modeling, biodegradability assessments, and field-scale application are proposed to support long-term geotechnical and ecological engineering deployment.

将棕榈纤维与微生物诱导碳酸钙沉淀（Microbially Induced Calcite Precipitation, MICP）技术相结合，为提升砂土的力学性能与耐久性提供了一种可持续的生物质基加固方案，尤其适用于冻融环境工况。本研究开展系统性实验探究，考察不同棕榈纤维掺量（0%~0.30%）对MICP固化砂土的承载力、固化层厚度、碳酸钙沉积效果以及抗冻融性能的影响。实验结果表明，土体力学性能随纤维掺量提升而增强，在掺量为0.15%时达到峰值；当掺量超过该最优值后，纤维发生团聚，加固效益出现衰减。相较于无纤维的MICP固化试样，最优掺量下试样的承载力提升24%，固化层厚度增加70.5%，碳酸钙含量可达16.8%。冻融测试结果显示，该复合固化试样的质量与强度保留率更高，表明其耐久性得到显著改善。通过扫描电子显微镜（Scanning Electron Microscope, SEM）、X射线衍射（X-ray Diffraction, XRD）、能量色散X射线光谱（Energy Dispersive Spectroscopy, EDS）以及傅里叶变换红外光谱（Fourier Transform Infrared Spectroscopy, FTIR）开展的微观结构分析表明，纤维-砂界面处的微生物附着效果增强，碳酸钙沉积更为均匀，从而提升了土体基质的黏结强度。本研究揭示了一种生物-力学协同加固机制，并指出了纤维掺量与孔隙连通性之间的权衡关系。该研究为纤维辅助生物矿化技术提供了全新的研究视角，同时为环保型土体加固技术提供了可行的发展路径。此外，本研究还提出了预测建模、生物降解性评估以及现场规模应用等未来研究方向，以支撑该技术在长期岩土与生态工程中的部署应用。