Evaluation of Sustainable and Environmentally Friendly Stabilization of Cohesionless Sandy Soil for Transportation Infrastructure

Ordinary Portland cement (OPC) is generally used to stabilize cohesionless sandy soils that are often found in coastal areas. Due to its high carbon footprint, many studies are being conducted to identify a suitable green alternative for stabilizing cohesionless soils. Previous studies have shown that partially replacing OPC with waste materials such as nano-silica and coal waste reduces the overall carbon footprint without significantly impacting the performance. Geopolymer (GP) received a lot of attention in the past few decades owing to its similar properties to that of OPC yet with a lower carbon footprint. This study investigated the feasibility of stabilizing cohesionless sandy soils with metakaolin-based GP. Engineering and characterization tests such as shrinkage, strength, pH, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) were performed to evaluate various characteristics of the stabilized mixes with different dosages of geopolymer and relate them to microstructural changes. Notably, GP-treated soils did not deteriorate during the durability tests, whereas the OPC-treated soil only retained about 75% of its strength. This is an indication that GP could be a better choice than OPC in coastal areas where cohesionless soils often experience heavy rainfall and flooding. Overall, an optimum dosage of GP improved both the mechanical properties and durability of cohesionless soils.普通硅酸盐水泥（Ordinary Portland Cement, OPC）通常用于加固沿海地区常见的无粘性砂土。鉴于其较高的碳足迹，学界正开展大量研究，以探寻适用于无粘性砂土固化的绿色替代固化材料。已有研究表明，采用纳米二氧化硅、煤炭废料等废弃物部分替代普通硅酸盐水泥，可在不对固化性能产生显著负面影响的前提下，降低整体碳足迹。地质聚合物（Geopolymer, GP）在过去数十年间广受关注，因其性能与普通硅酸盐水泥相近，却拥有更低的碳足迹。本研究探究了采用偏高岭土基地质聚合物固化无粘性砂土的可行性。本研究开展了收缩试验、强度测试、pH值检测、扫描电子显微镜（SEM）、能量色散X射线光谱（EDS）等工程与表征试验，以评估不同地质聚合物掺量下固化混合料的各项特性，并将其与微观结构变化建立关联。值得注意的是，经地质聚合物固化的砂土在耐久性试验中未出现劣化，而经普通硅酸盐水泥固化的砂土仅保留约75%的强度。这表明，在无粘性砂土常遭遇强降雨与洪涝的沿海地区，地质聚合物或许是比普通硅酸盐水泥更优的固化材料。总体而言，最佳掺量的地质聚合物可同时提升无粘性砂土的力学性能与耐久性。