首页|水泥基复合材料固化铬污染盾构渣土性能及其机理研究

水泥基复合材料固化铬污染盾构渣土性能及其机理研究

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为了实现铬污染盾构渣土的资源化利用，解决单一水泥固化材料用量大、排放量高以及固化效果不理想等问题，研制水泥基有机-无机复合固化剂固化铬污染盾构渣土。以14 d养护龄期固化土无侧限抗压强度和浸出毒性为评判指标，通过设计"五因素四水平"正交试验确定复合固化剂最佳配比;采用极差分析法对各影响因素进行主效应分析，并结合XRD和SEM试验探究复合有机-无机固化剂的作用机理。研究结果表明:无侧限抗压强度和浸出毒性评判指标的最优解均为11%(质量分数，下同)水泥、5。50%生石灰、0。25%聚丙烯酰胺、1。10%硅酸钠和0。05%海藻酸钠;14 d养护龄期的试验13(A4B1C4D4E1)固化土无侧限抗压强度达1 217。58 kPa，重金属铬浸出质量浓度为2。4 mg/L，满足相关规范要求;水泥、海藻酸钠和硅酸钠为固化土无侧限抗压强度评判指标的主要影响因素，水泥、海藻酸钠和生石灰为浸出毒性评判指标的主要影响因素;固化土无侧限抗压强度与重金属铬浸出质量浓度密切相关，具体表现为固化土无侧限抗压强度越大，重金属铬的稳定化效果越明显;大量的自由水被消耗、pH升高、新矿物的生成、土体微观结构改变及土颗粒间胶结作用增强是盾构渣土性能提高的主要原因;当固化土强度增大时，重金属铬的物理封闭作用增强;此外，发生水化反应形成的较高pH也促进三价铬生成难溶于水的氢氧化物沉淀，从而降低固化土重金属铬浸出毒性。
Study on properties and mechanism of cement-based composite materials solidifying chromium-contaminated shield muck
A cement-based composite curing agent was developed for solidifying chromium-contaminated shield muck to overcome the problems of high emissions and unsatisfactory curing performance of single curing materials,and to realize resource utilization.A five-factor and four-level orthogonal test was designed to determine the optimum ratio of the composite curing agent,using the unconfined compression strength and leaching toxicity of the cured soil at 14 d of age as the evaluation index.The main effect analysis of each influencing factor was carried out by using the method of extreme deviations analysis,and the mechanism of the compound organic-inorganic curing agent was investigated by combining XRD and SEM tests.The results show that the optimum solution of the two evaluation indexes of unconfined compression strength and leaching toxicity is that the mass fractions of cement,quicklime,polyacrylamide,sodium silicate and sodium alginate are 11% ,5.50% ,0.25% ,1.10% and 0.05% ,respectively.The unconfined compressive strength of the cured soil in No.13 test reaches 1 217.58 kPa and the leaching mass concentration of heavy metal chromium is 2.4 mg/L at the age of 14 d,which meets the requirements of the relevant specifications.Cement,sodium alginate and sodium silicate are the main influencing factors for the evaluation index of unconfined compressive strength of cured soil,and cement,sodium alginate and quicklime are the main influencing factors for the evaluation index of leaching toxicity.The unconfined compressive strength of cured soil is closely related to the leaching mass concentration of chromium heavy metal,which shows that the greater the unconfined compressive strength of cured soil,the more obvious the stabilization effect of chromium heavy metal.A large amount of free water is consumed,and the increase of pH,the formation of new minerals and the microstructural changes of the soil are the main factors for the improved performance of the shield muck.The increase in strength of the cured soil is accompanied by the increase of the physical confinement of the heavy chromium metal.In addition,the higher pH at which the hydration reaction occurs also promotes the formation of water-insoluble hydroxide precipitates of trivalent chromium,thus reducing the toxicity of the leaching of heavy chromium metal from the cured soil.

chromium-contaminated shield muckcomposite solidifying materialorthogonal testunconfined compressive strengthleaching toxicitymicroscopic mechanism

魏贺、贺勇、阳栋、张可能、娄伟、史继彪、冯德山

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中南大学有色金属成矿预测与地质环境监测教育部重点实验室,湖南长沙,410083

中南大学地球科学与信息物理学院,湖南长沙,410083

中国建筑第五工程局有限公司,湖南长沙,410004

湖南省和清环境科技有限公司,湖南长沙,410221

徐州中矿岩土技术股份有限公司,江苏徐州,221116

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铬污染盾构渣土 复合固化材料 正交试验 无侧限抗压强度 浸出毒性 微观机制

国家自然科学基金资助项目国家自然科学基金资助项目国家自然科学基金资助项目中南大学创新驱动计划项目湖南省自然资源厅自然资源一般项目

4207231841972282418072532023CXQD0442022-30

2024

10.11817/j.issn.1672-7207.2024.02.006

中南大学学报(自然科学版)
中南大学

中南大学学报(自然科学版)

CSTPCD北大核心
影响因子：0.938
ISSN：1672-7207
年,卷(期)：2024.55(2)
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