活性氧化镁碳化加固粉土微观机理研究

发布时间：2018-04-28 04:20

本文选题：氧化镁 + 粉土　；参考：《土木工程学报》2017年05期

【摘要】：基于活性Mg O-CO2碳化固化法,开展了不同活性Mg O掺量、碳化时间和初始含水率条件下的碳化粉土的无侧限抗压试验、X-射线衍射(XRD)、扫描电镜(SEM)和压汞试验(MIP)等,以通过无侧限抗压强度、化学成分、结构形貌和微观孔隙等特征来揭示碳化固化粉土的微观机理,最后提出活性Mg O碳化固化粉土微观机理模型。结果表明:活性Mg O碳化固化粉土的无侧限抗压强度在12h内随Mg O掺量和碳化时间增加而增加,随初始含水率增加而降低;碳化后含水率显著降低,且强度与含水率间呈很好的线性负相关关系。碳化生成的水化镁式碳酸盐,包括棱柱状水菱镁石、薄片状球菱镁石/水碳镁石和纤维碳镁石,这些碳化产物对应的XRD峰强随Mg O掺量和碳化时间增加而增加,随初始含水率增加而降低;存在最优Mg O掺量和初始含水率,使碳化土孔隙体积最小。碳化土无侧限抗压强度与水菱镁石晶体对应的XRD峰强呈正相关关系。水菱镁石的生成促进了强度增长,与其他碳化产物共同促进土体孔隙减小。
[Abstract]:Based on the active mg O-CO2 carbonation curing method, the unconfined compressive tests of carbonated silt with different active mg / O content, carbonation time and initial moisture content were carried out, such as X- ray diffraction (X- ray diffraction), scanning electron microscope (SEM) and mercury injection test (MIP), etc. The microscopic mechanism of carbonation solidified silt was revealed by the characteristics of unconfined compressive strength, chemical composition, structural morphology and micro-porosity. Finally, the microscopic mechanism model of activated MgO carbonation solidified silt was put forward. The results show that the unconfined compressive strength of activated MgO carbonized silt increases with the increase of MgO content and carbonation time within 12 h, and decreases with the increase of initial moisture content, and the moisture content decreases significantly after carbonization. There is a good linear negative correlation between strength and moisture content. The hydrated magnesium carbonate formed by carbonation, including prism magnesite, thin spheroidal magnesite / water carburite and fibrous carbon magnesium, the XRD peak strength of these carbonized products increases with the increase of MgO content and carbonation time. With the increase of initial water content, the pore volume of carbonized soil is minimized by the existence of optimal MgO content and initial water content. The unconfined compressive strength of carbonized soil is positively correlated with the XRD peak strength of magnesite crystal. The formation of water magnesite promotes the increase of strength and, together with other carbonation products, promotes the decrease of soil porosity.
【作者单位】：东南大学岩土工程研究所;江苏省城市地下工程与环境安全重点实验室;
【基金】：国家自然科学基金(51279032) “十二五”科技支撑计划(2012BAJ01B02-01) 中央高校基本科研业务费专项江苏省普通高校研究生科研创新计划(KYLX_0147)
【分类号】：TU472

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