水泥固化锌污染红粘土力学性能及固化机理研究

发布时间：2018-02-26 08:56

本文关键词： 锌污染红粘土水泥固化/稳定无侧限抗压强度淋滤试验微观孔隙 XRD分析　出处：《内蒙古农业大学》2017年硕士论文　论文类型：学位论文

【摘要】：锌矿的开采、镀锌、仪器仪表及机械制造等工业活动,使土壤受到重金属锌的污染,其中红粘土受到的锌污染更为严重。为治理受到重金属锌污染的红粘土,使用水泥固化法(S/S法)对污染土进行固化处理,研究处理后固化物的力学特性、工程特性、化学稳定性及固化机理。为污染土固化物作为浅层地基或护岸等非敏感区域的建筑材料提供一定的基础数据,期望达到污染土治理及二次利用的目的。主要研究成果如下:(1)将硝酸锌溶液与风干后红粘土进行混合,配置不同浓度的人工污染土,掺入水泥经不同养护龄期固化后,进行无侧限抗压强度试验。研究了锌浓度、水泥掺量和养护龄期对固化物无侧限抗压强度、破坏应变及变形模量的影响;分析了各浓度固化物的应力-应变曲线;提出了锌影响固化物力学特性的阈值浓度;探讨了以锌浓度、水泥掺量和养护龄期为影响因素的无侧限强度预测方法。(2)通过对污染土固化物进行淋滤试验,研究了不同锌浓度、水泥掺量和养护龄期对固化物稳定性的影响。分析了固化物稳定性的影响因素;得出当水泥掺量10%时,锌污染红粘土固化物稳定性较佳;提出固化过程中对于稳定性起主要作用的是红粘土对锌的吸附,而水泥的水化反应对重金属锌的包裹和禁锢起着协同作用的观点。(3)通过对固化物体积、含水量和质量的测定。研究各影响因素对固化物含水率、体积和质量的影响规律;提出高浓度的锌可以改变红粘土的性质,使红粘土出现亲水性,导致固化物在标准养护情况下吸水膨胀;得出提高固化物的水泥掺量,可有效减小固化物膨胀,提高其无侧限抗压强度,增加受污染的红粘土的工程适用性的结论;提出了根据固化物干质量的变化规律分析固化物水化反应程度的方法。(4)采用压汞试验研究了固化物的孔结构。从细观和微观角度探讨了固化物的固化机理。(5)通过对固化物进行XRD等试验,研究不同养护阶段固化物的化学生成物,分析了其各阶段固化物的化学反应机理。发现固化物养护后期会产生Si02结晶物,提出在养护后期Si02结晶会起到骨料作用与水化反应生成的水合硅酸钙互相胶结是固化物后期强度的主要来源的观点。
[Abstract]:Industrial activities such as zinc mining, galvanizing, instrumentation and mechanical manufacturing have made the soil polluted by heavy metal zinc, among which the red clay is more seriously polluted by zinc. In order to control the red clay contaminated by heavy metal zinc, The cement curing method is used to cure the contaminated soil, and the mechanical and engineering properties of the cured soil after treatment are studied. Chemical stability and solidification mechanism. Provide certain basic data for contaminated soil solidification as building materials in non-sensitive areas such as shallow foundation or bank revetment. The main research results are as follows: 1) mixing zinc nitrate solution with air-dried red clay, mixing different concentrations of artificially contaminated soil, and mixing cement with cement after curing at different curing ages. The effects of zinc concentration, cement content and curing age on the unconfined compressive strength, failure strain and deformation modulus of the cured compounds were studied, and the stress-strain curves of the solidified compounds were analyzed. The threshold concentration of zinc affecting the mechanical properties of solidified soils is put forward, and the prediction method of unconfined strength, which takes zinc concentration, cement content and curing age as the influencing factors, is discussed. Different zinc concentrations are studied through leaching tests on the solidified compounds of contaminated soil. The influence of cement content and curing age on the stability of solidified clay was analyzed, and the results showed that the stability of zinc contaminated red clay was better when the cement content was 10%. It is suggested that the adsorption of zinc by red clay is the main factor in the stability of the solidification process, while the hydration reaction of cement plays a synergistic role on the encapsulation and confinement of heavy metal zinc. Determination of water content and mass. The effect of various factors on the water content, volume and mass of cured compounds was studied, and it was suggested that high concentration of zinc could change the properties of red clay and make red clay hydrophilic. It is concluded that increasing the cement content of cured compounds can effectively reduce the expansion of solidified compounds, increase their unconfined compressive strength and increase the engineering applicability of contaminated red clay. The method of analyzing the degree of hydration reaction of cured compounds according to the variation law of dry mass of solidified compounds was put forward. The pore structure of cured compounds was studied by mercury injection test. The solidification mechanism of cured compounds was discussed from the microcosmic and microcosmic angles. The XRD and other tests were carried out on the solidified compounds. The chemical products of solidified compounds in different curing stages were studied, and the chemical reaction mechanism of solidified compounds in each stage was analyzed. It was found that Si02 crystals would be produced in the later curing stages of cured compounds. It is pointed out that the hydration of calcium silicate hydrated during the later curing period is the main source of the later strength of the solidified compound, and the crystallization of Si02 will act as aggregate and the hydration reaction will result in the mutual cementation of calcium silicate hydrate.
【学位授予单位】：内蒙古农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X53

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