活性MgO碳化固化土的干湿循环特性试验研究

发布时间：2018-03-28 06:24

本文选题：土体固化　切入点：碳化　出处：《岩土工程学报》2016年02期

【摘要】：碳化固化技术是一种利用二氧化碳对搅拌有活性氧化镁的土体进行碳化,以达到快速提高强度的低碳搅拌处理软土的创新技术。通过室内试验研究干湿循环对碳化固化土物理力学特性的影响,并与相同掺量下水泥固化土进行对比。结果表明:活性Mg O固化粉土碳化3 h试样的无侧限抗压强度可达5 MPa,粉质黏土碳化24 h试样可达2.6 MPa;干湿循环后碳化固化土的干密度降低,而水泥土干密度基本不变;6次干湿循环后粉土碳化试样的无侧限抗压强度仍然能达到4 MPa以上,为水泥固化粉土强度的2倍,具有较好的抗干湿循环性能;经过6次干湿循环后,粉质黏土碳化试样的残余强度仅为35%,而水泥固化粉质黏土降到65%,表明固化粉质黏土的抗干湿循环性能均较差,且粉质黏土碳化试样的抗干湿循环能力不及水泥固化粉质黏土试样。通过X射线衍射(XRD)、电镜扫描(SEM)及压汞试验(MIP)测试表明干湿循环对粉土碳化试样的累计孔隙影响不大,因此粉土试样仍然具有比较大的密实度来保证试样强度;粉质黏土碳化试样因孔隙增加明显而变得疏松,因此强度显著降低。
[Abstract]:Carbonization and curing is a carbonization of soil mass stirred with active magnesium oxide using carbon dioxide. In order to improve the strength of soft soil with low carbon agitation, the effect of dry and wet cycle on the physical and mechanical properties of carbonized solidified soil was studied through laboratory tests. The results show that the unconfined compressive strength of activated MgO solidified silt for 3 h carbonization can reach 5 MPA, the carbonization time of silty clay 24 h can reach 2.6 MPA, and the carbonation of dry and wet cycles can be achieved. The dry density of chemical soil decreased, The unconfined compressive strength of the carbonized silt can still reach more than 4 MPa after 6 dry and wet cycles, which is 2 times of the strength of cement solidified silt, and has better resistance to dry and wet cycling. After 6 dry and wet cycles, the residual strength of carbonized silty clay is only 35, while the cement cured silty clay is reduced to 65, which indicates that the dry and wet cycle resistance of the cured silty clay is poor. The dry and wet cycle resistance of carbonized silty clay samples is not as good as that of cement solidified silty clay samples. The results of X-ray diffraction (XRD), scanning electron microscopy (SEM) SEM) and mercury injection test (MIP) show that dry and wet cycling has little effect on the cumulative porosity of silt carbonized samples. Therefore, silt samples still have a relatively large compactness to ensure the strength of the samples, and the carbonation samples of silty clay become loose because of the increase of porosity, so the strength of the samples decreases significantly.
【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】：国家自然科学基金项目(51279032) 国家科技支撑项目(2012BAJ01B02-01) 中央高校基本科研业务费专项资金项目江苏省普通高校研究生科研创新计划资助项目(KYLX_0147)
【分类号】：TU41

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