初始含水率对活性MgO碳化红黏土特性的影响

Effect of initial water content on characteristics of reactive MgO carbonated red clay

针对红黏土不良物理力学特性造成的工程问题,采用活性MgO结合CO_(2)碳化加固技术对其进行改良。通过一系列土工试验探究不同初始含水率和碳化时间对试样物理力学特性的影响;结合扫描电子显微镜(scanning electron microscope,SEM)试验,揭示活性MgO碳化固化红黏土的微观结构变化。结果表明:改良后红黏土的质量和体积明显增加,显著改善了红黏土高含水量的不良特征,同时有效吸收CO_(2)气体(18%~42%);活性MgO碳化固化红黏土的强度能够在较短时间内得到提升,但强度的提升幅度受到初始含水率和碳化时间的影响,且无侧限抗压强度与CO_(2)吸收率保持良好的一致性。通过微观结构分析发现,碳酸镁石、球碳镁石和水菱镁石等水合碳酸镁产物是碳化固化红黏土物理特性变化及强度提升的主要原因。活性MgO碳化固化红黏土具有较好的优势,能够有效改善红黏土的物理力学性能。

Aiming at the engineering problems caused by poor physical and mechanical properties of red clay,reactive MgO combined with CO_(2)carbonation reinforcement technology was used to improve it.The effects of different initial water content and carbonation time on physical and mechanical properties of samples were obtained by a series of soil experiments.The change of the microstructure of reactive MgO carbonated red clay was revealed by the scanning electron microscope(SEM).The results show that the mass and volume of the sample are significantly increased with the adverse characteristic of high water content of red clay significantly improved,and the CO_(2)gas is effectively absorbed(18%-42%).The strength of reactive MgO carbonated red clay can be improved in a short time.However,the increment of strength is affected by initial water content and carbonation time,and the unconfined compressive strength is consistence with CO_(2)absorption rate.According to microstructure analysis,the hydrated magnesium carbonate product such as nesquehonite,dypingite,hydromagnesite is the main reason for the improvement of physical properties and strength of carbonated red clay.Reactive MgO carbonated red clay has good advantages and can effectively improve the physical and mechanical properties of red clay.