粒化高炉矿渣和氧化镁固化稳定化铅污染粘土的强度、溶出及微观特性的研究

发布时间：2018-02-26 02:00

本文关键词： 铅污染 GGBS-MgO 稳定/固化物理化学性强度特性环境安全性微观机理　出处：《东南大学》2015年硕士论文　论文类型：学位论文

【摘要】：粒化高炉矿渣粉(GGBS)作为一种绿色低碳可持续发展材料,被广泛作为水泥基材料添加料。活性氧化镁(MgO)可以有效激发GGBS,提高激发后GGBS的无侧限抗压强度。但目前对GGBS-MgO作为重金属污染粘土固化剂研究存在不足,本文以国家863计划课题(2013AA06A206)、国家自然科学基金重点项目(41330641)、国家自然科学基金项目(51278100,41472258)和江苏省自然科学基金杰出青年基金项目(BK2012022)为依托,采用GGBS-MgO作为固化剂加固铅污染粘土,并通过酸缓冲能力测试、无侧限抗压强度试验、毒性浸出试验及半动态浸出试验,对GGBS-MgO固化铅污染土进行物理化学特性、强度特性、环境安全性及微观机理的分析研究,并对GGBS-MgO和水泥固化现场铅锌镉复合污染土进行对比研究。得到的主要研究结论如下：(1)物理化学特性：标准养护及半动态浸出条件下,GGBS-MgO固化铅污染土pH均低于固化未污染土,半动态浸出试验后,同一配比试样内部pH在淋滤液初始pH=2.0-7.0时相差不大,而试样表层pH在淋滤液初始pH=2.0时约为pH=3.0-7.0时的1/2; GGBS-MgO固化铅污染土相比于水泥固化铅污染土有较强的酸缓冲能力。(2)强度特性：GGBS-MgO固化铅污染土针刺深度约为固化未污染土的1.4-3.2倍,且无侧限抗压强度qu均较固化未污染土小；随着固化剂掺量增加,试样针刺深度逐渐减小,强度随之升高;半动态浸出试验后,试样随着淋滤液初始pH增大,试样针刺深度逐渐减小,qu增加,试样qu较标准养护39 d试样qu降低了2%-53%；在同等条件下GGBS-MgO固化未污染土半动态浸出后qu较水泥固化未污染土qu提高了12%-43%,且在18%掺量下约为水泥固化铅污染土1.3-1.8倍。(3)环境安全性：TCLP试验表明随着固化剂掺量的增加,铅溶出率明显下降；半动态浸出试验表明同等掺量、同等试验条件下,淋滤液初始pH=7.0时,GGBS-MgO固化土扩散系数相比于水泥固化土低1-2个数量级；通过三种方法计算扩散系数,初始淋滤液pH=2.0时铅的溶出机制为溶解,随着pH增加溶出机制由溶解转为扩散。(4)微观机理：X射线衍射结果表明GGBS-MgO固化铅污染土有明显水合硅酸镁和Ht生成,铅的固定形式主要为表面吸附与沉淀；扫描电镜结果表明,GGBS-MgO固化土试样标准养护28 d时主要水化产物为C-S-H与Ht,铅污染的掺入使C-S-H与Ht在形态上有所改变；压汞试验结果表明,随着龄期增加,试样累积孔隙减少：固化剂掺量增加会使试样内部孔隙更加致密,铅污染的掺入使得试样孔隙增加：半动态浸出结束后,试样孔径相比于同龄期试样增大,GGBS-MgO固化士孔隙比水泥固化土更为致密。通过上述试验研究表明,GGBS-MgO作为固化剂固化铅污染粘土在强度特性、环境安全性上都优于水泥,可将其作为固化剂代替水泥固化铅污染粘土。
[Abstract]:Granulated blast furnace slag powder (GGBS) is a green and low carbon material for sustainable development. Active magnesium oxide (MgO) can effectively excite GGBs and improve the unconfined compressive strength of activated GGBS. However, the study of GGBS-MgO as a curing agent for heavy metal contaminated clay is insufficient. In this paper, based on the National 863 Program project (2013AA06A206), the National Natural Science Foundation's key project (41330641U), the National Natural Science Foundation's project No. 51278100 (41472258) and the outstanding youth fund of Jiangsu Provincial Natural Science Foundation (BK2012022), GGBS-MgO is used as the curing agent to strengthen lead-contaminated clay. Through acid buffer capacity test, unconfined compressive strength test, toxic leaching test and semi-dynamic leaching test, the physical and chemical properties, strength characteristics, environmental safety and microscopic mechanism of GGBS-MgO solidified lead-contaminated soil were analyzed and studied. The main conclusions are as follows: the physical and chemical properties of Pb-Zn / CD composite contaminated soil cured by GGBS-MgO and cement curing site are as follows: the pH of GGBS-MgO solidified lead-contaminated soil is lower than that of solidified uncontaminated soil under standard curing and semi-dynamic leaching conditions. After semi-dynamic leaching test, the internal pH of the same ratio sample had little difference at the initial pH=2.0-7.0 of the leachate. The pH value of the surface layer of the sample was about 1 / 2 of that of pH=3.0-7.0 at the initial pH=2.0 of leaching solution, and the strength of the lead-contaminated soil cured by GGBS-MgO was 1.4-3.2 times of that of the uncontaminated soil, compared with that of the lead-contaminated soil solidified by cement. The strength characteristics of the lead-contaminated soil solidified with GGBS-MgO were 1.4-3.2 times as deep as that of the uncontaminated soil cured by GGBS-MgO. The unconfined compressive strength qu is smaller than that of the uncontaminated soil, the depth of needling decreases gradually and the strength increases with the increase of the content of curing agent, after semi-dynamic leaching, the sample increases with the initial pH of leaching solution. The needling depth of the sample gradually decreased and increased. After semi-dynamic leaching of uncontaminated soil cured by GGBS-MgO under the same conditions, it increased 12-43x than that of uncontaminated soil cured by cement, and was about 1.3-1.8 times as much as that of cement-cured lead-contaminated soil at 18%). The environmental safety: TCLP test showed that with the increase of the amount of curing agent, The semi-dynamic leaching test showed that the diffusion coefficient of GGBS-MgO solidified soil was 1-2 orders of magnitude lower than that of cement solidified soil at the initial pH=7.0 of leaching filtrate under the same amount of content, and the diffusion coefficient was calculated by three methods. The dissolution mechanism of lead in the initial leaching filtrate pH=2.0 was dissolution. With the increase of pH, the dissolution mechanism changed from dissolution to diffusion. The microcosmic X-ray diffraction results showed that GGBS-MgO solidified lead contaminated soil had obvious hydrated magnesium silicate and Ht formation. The results of SEM showed that the main hydration products of GGBS-MgO solidified soil for 28 days were C-S-H and Ht.The incorporation of lead pollution changed the morphology of C-S-H and Ht. With the increase of age, the cumulative porosity of the sample decreases: the increase of the amount of curing agent will make the internal pore of the sample more compact, and the incorporation of lead pollution will increase the pore of the sample: after the semi-dynamic leaching, The pore size of GGBS-MgO solidified clay is denser than that of cement solidified soil. The experimental results show that GGBS-MgO solidified lead-contaminated clay is superior to cement in terms of strength and environmental safety. It can be used as curing agent instead of cement curing lead contaminated clay.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53;TU43

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