偏高岭土基地聚物改良土最优配比及固化效果分析

地聚物是一种具有快硬、高强、低收缩等特点的新型绿色胶凝材料,对于改善软弱土体的坚固性、稳定性和耐久性十分有利。通过对偏高岭土基地聚物改良土开展不同配比下的强度特性试验及扫描电镜试验,探讨了地聚物改良土的最佳配比,分析了地聚物材料组分对改良土力学特性及固化效果的影响,结果表明：地聚物改良土抗压强度随偏高岭土和碱激发剂掺量的增加呈现先增后减趋势,偏高岭土和碱激发剂掺量最优配比为2：1,且二者在土中的最经济掺入比为12%；相同掺比下的地聚物改良土和普通硅酸盐水泥土、以及纯黏土的抗压、抗剪、抗劈裂强度及电镜扫描结果则表明,地聚物改良土强度性能均优于其他两者,团聚固化效应依次减弱；地聚物改良土破坏现象表明,随着地聚物掺量增加,其破坏模式由塑性剪切破坏向脆性劈裂破坏发展。本文成果可为偏高岭土基地聚物改良土的应用推广提供参数设计依据。

Analysis on optimum proportion and stabilization effect of metakaolin-based geopolymer soil

Geopolymer is a new type of green cementitious material with characteristics of fast hardening, high strength, and low shrinkage. It is very beneficial to ensure the firmness, stability, and durability of soft soils. In this study, the strength test and scanning electron microscope of metakaolin-based geopolymer soil were carried out with different material ratios first, and then the optimum mixing ratio of the geopolymer soil was analyzed. The impacts of metakaolin and alkali activator on the mechanical properties and stabilization effect of geopolymer soil were also discussed in the final. Outcomes indicate that the peak unconfined compression strength of the geopolymer soil increases first and then decreases with the contents of the metakaolin and alkali activator. The optimum ratio of metakaolin and alkali activator in geopolymer soil is 2:1, and the cost-optimal blending ratio of geopolymer in the soil is about 12%. Parallel comparative experiments and SEM tests for the soils with the same content of geopolymer and ordinary Portland cement, and the pure soil show that the geopolymer-improved soil has the best strength performance than the others, no matter in compression, shear or tensile strength; the agglomeration and stabilization effects of them are weakened in turn. The macroscopic fracture mode of soil samples with different geopolymer contents shows that the failure of them develops from ductile shear fracture to brittle normal tensile fracture. The results of this study can provide a parameter basis for the application and popularization of the geopolymer-improved soil.