Normalized intensity.

This study systematically investigates the influence of cementation solution concentration on the sand fixation effect induced by palm fiber-enhanced microorganisms through microbial induced calcium carbonate precipitation (MICP), aiming to optimize its application in ecological restoration and engineering reinforcement. A series of experiments including unconfined compressive strength tests, direct shear tests, permeability tests, nuclear magnetic resonance analysis, calcium carbonate content determination, scanning electron microscopy (SEM), and X-ray diffraction (XRD) evaluates the mechanical properties, permeability, and microstructural characteristics of MICP-treated sand under varying cementation concentrations ranging from 0.2 to 0.7 mol/L. Results show that a concentration of 0.5 mol/L yields the best mechanical performance, with significantly higher unconfined compressive strength (666.65 kPa) and shear strength compared to other concentrations. At lower concentrations from 0.2 to 0.4 mol/L, increasing the concentration enhances calcium carbonate deposition, which improves mechanical properties and reduces both permeability coefficient and porosity. In contrast, higher concentrations above 0.5 mol/L inhibit microbial enzymatic activity, leading to reduced calcium carbonate content and mechanical strength, along with increased permeability and porosity. Microscopic analysis reveals that at 0.5 mol/L, calcium carbonate crystals form densely and uniformly, effectively filling pore spaces and strengthening inter-particle bonding. Therefore, 0.5 mol/L represents an optimal balance between performance and cost, reducing resource waste while ensuring mechanical enhancement and supporting applications in sand dune stabilization, windbreaks, sand fixation, and ecological vegetation restoration.

本研究系统探究了胶结液浓度对棕榈纤维增强微生物通过微生物诱导碳酸钙沉淀（MICP）产生的固沙效果的影响，旨在优化其在生态修复与工程加固领域的应用。本研究通过一系列试验——包括无侧限抗压强度试验、直剪试验、渗透性试验、核磁共振分析、碳酸钙含量测定、扫描电子显微镜（SEM）及X射线衍射（XRD）——对胶结液浓度介于0.2~0.7 mol/L范围内的MICP固化砂的力学性能、渗透特性与微观结构特征进行了评价。研究结果表明，浓度为0.5 mol/L时综合力学性能最优，其无侧限抗压强度（666.65 kPa）与抗剪强度均显著高于其余浓度组。当浓度处于0.2~0.4 mol/L的较低区间时，提升胶结液浓度可促进碳酸钙沉积，进而改善力学性能并降低渗透系数与孔隙率。与之相反，当浓度高于0.5 mol/L时，会抑制微生物酶活性，导致碳酸钙沉积量与力学强度下降，同时渗透系数与孔隙率升高。微观表征结果显示，在0.5 mol/L浓度下，碳酸钙晶体致密且均匀地生成，可有效填充孔隙空间并强化颗粒间的粘结作用。综上，0.5 mol/L为性能与成本的最优平衡点，既可减少资源浪费，又能保障力学增强效果，可应用于沙丘稳固、防风固沙及生态植被修复等场景。