基于矿渣复合固化剂固化滨海盐渍土的机理及固化体性能研究

发布时间：2018-02-15 02:16

本文关键词： 滨海盐渍土抗压强度水稳性耐久性　出处：《北京科技大学》2015年博士论文　论文类型：学位论文

【摘要】：滨海盐渍土中含有大量可溶性盐,使盐渍土具有盐胀性、溶陷性、腐蚀性、吸湿软化性等工程特性。滨海地区的工程建设都涉及对其进行固化利用的问题。由于以往固化方法处理费用高、固化效果差等诸多方面的缺陷,因此迫切需要新型固化剂,以确保工程安全和投资合理。在对曹妃甸滨海盐渍土和矿渣料宏细观结构特征、化学性能进行综合分析的基础上,提出利用矿渣复合固化剂进行盐渍土固化的技术思路,并确定出矿渣复合固化剂的性能要求。通过抗压强度试验、水稳性试验、可溶性离子含量测定试验、SEM分析试验、EDS能谱分析试验和XRD分析试验,测试了矿渣复合固化剂固化盐渍土(固化土)的无侧限抗压强度、水稳性、可溶性离子含量,耐久性,溶陷性和盐胀性,观察了固化土的微观形貌,分析了固化土水化产物的组成,探讨了矿渣复合固化剂对盐渍土的固化机理。结果表明：与水泥土相比,矿渣复合固化剂固化土的无侧限抗压强度较大,水稳性较强,耐久性好,抗溶陷性强,抗盐胀性强,能满足一般工程地基固化处理的要求。由于盐渍土中可溶性Cl-、SO42-和Na+参与了矿渣复合固化剂的水化反应,并生成了新的水化产物片状晶体和针棒状晶体(3CaO·Al2O3·(0.5CaCl2·0.5CaSO4)·12H2O),副产品NaOH为矿渣提供了更强的碱性环境,并生成了沸石类物质(0.8CaO·0.2Na2O·Al2O3·3SiO2·6H2O),因此固化土可溶性Cl-、SO42-和Na+含量较低。滨海盐渍土通过矿渣复合固化剂的三级固化作用,使固化土无侧限抗压强度较大,水稳性较强,抗溶陷性强,抗盐胀性强,解决了盐渍土的一些潜在危害。矿渣复合固化剂固化土在海水中会生成的致密坚硬的CaCO3外壳,随着龄期的增长,该外壳越来越厚。CaCO3晶体在海水中会稳定存在,不会与海水中的其它离子发生化学反应,从而阻止了海水对试块内部的侵蚀,也阻止了Ca(OH)2的溶出型侵蚀,这可能是矿渣复合固化剂具有良好抗海水侵蚀性能的根本原因。矿渣复合固化剂的最优配比为：矿渣75%,生石灰7.5%,石膏7.5%,菱苦土10%。其主要组分是矿渣,成本为水泥的60%-70%,是一种绿色环保型固化剂。
[Abstract]:The seaside saline soil contains a large amount of soluble salt, which makes the saline soil have salt expansion, solution and corrosion. Engineering characteristics such as moisture absorption and softening. Engineering construction in coastal area involves the problem of curing and utilizing it. Due to the shortcomings of the former curing methods, such as high cost and poor curing effect, new curing agents are urgently needed. To ensure project safety and reasonable investment. Based on the comprehensive analysis of macrostructural characteristics and chemical properties of salinized soil and slag in Caofeidian, the technical idea of solidifying salinized soil by using compound solidifying agent of slag is put forward. The performance requirements of slag compound hardener were determined. Through compressive strength test, water stability test, soluble ion content determination test, SEM analysis test, EDS energy spectrum analysis test and XRD analysis test, The unconfined compressive strength, water stability, soluble ion content, durability, solubility and salt swelling of solidified saline soil with slag compound curing agent were tested, and the microstructure of solidified soil was observed. The composition of hydration products of solidified soil was analyzed, and the mechanism of solidification of salinized soil by slag compound curing agent was discussed. The results showed that compared with cement soil, the unconfined compressive strength and water stability of solidified soil with slag compound curing agent were higher than that of cement soil. It has good durability, strong resistance to solution, strong resistance to salt dilatancy, and can meet the requirements of general engineering foundation curing treatment. Because soluble Cl-so _ 42- and Na in saline soil participate in the hydration reaction of slag compound curing agent, A new hydration product, flake crystal and needle rod crystal, 3CaO 路Al2O3 路N0.5CaCl2 路0.5CaSO4) 路12H2O were formed. The by-product NaOH provided a stronger alkaline environment for slag. A zeolite material of 0.8CaO 路0.2Na _ 2O 路Al2O3 路3SiO _ 2 路6H _ 2O was formed, so the content of soluble Cl-so _ 4- and Na in solidified soil was lower. The third-stage solidification of seashore saline soil through slag compound curing agent made the unconfined compressive strength, water stability and solution resistance of solidified soil higher. The salt swelling resistance is strong, which solves some potential hazards of salinized soil. The dense and hard CaCO3 shell formed by slag composite curing agent solidified soil in seawater. With the increase of age, the shell thicker and thicker. CaCO3 crystals will exist stably in seawater and will not react with other ions in seawater. Thus, the erosion of seawater to the inner part of the specimen and the dissolution of Ca(OH)2 were prevented, which may be the fundamental reason that the slag compound curing agent has good resistance to seawater erosion. The optimum ratio of slag compound curing agent is as follows: slag 75, quicklime 7.5, gypsum 7.5, rhombic soil 10. The main component is slag, the cost is 60-70 of cement, it is a kind of green environmental protection curing agent.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TU448

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