摘要
以固化重金属工业污染土为研究对象,采用两种碱激发水泥固化剂(A、B)对重金属污染土进行固化稳定处理。选用pH值、无侧限抗压强度试验、浸出和形态提取试验分别研究固化剂掺量和养护龄期对固化土强度、浸出及赋存形态的影响规律。强度和浸出试验结果表明:由火碱、偏高龄土或由消石灰、泡花碱组成的两种碱激发剂与普通硅酸盐水泥构成的固化剂(A、B)均可以改善污染土的强度特性,降低重金属Cd、Pb、As、Zn的溶出,随着固化剂掺量和养护龄期的增加,固化土A和B的强度、浸出及赋存形态均明显改善。但相同掺量和养护龄期条件下,固化土A的强度、溶出均好于固化土B。赋存形态试验结果表明:固化土A中Cd、Pb、As、Zn形态稳定性明显优于固化土B中的同类重金属,固化剂A可将污染土中的Cd、Pb、As、Zn从弱酸态向可氧化态和残渣态转化,而固化剂B可将污染土中的Cd、Pb、As、Zn从弱酸态向可还原态转化。固稳机制不同是固化土A、B的强度、浸出及赋存形态差异的根本原因。
Two alkali-activated cement(A and B)were used to stabilize and cement the combined heavy metal contaminated soil.The pH value,unconfined compressive strength,leaching and sequential extraction tests were used to investigate the effects of cement content and curing age on strength,leachability and speciation distribution of heavy metals contaminated soil stabilized by alkali-activated cement.The results showed that the alkali-activated cement A and B respectively composed of ordinary Portland cement with two kinds of alkali activator(caustic soda and metakaolin,or slaked lime and sodium silicate)to improve the mechanical properties of the soil and reduced the leachability of heavy metals.With the increase of cement content and curing age,the strength,leachability and speciation properties were improved.With the same cement content and curing age,the strength and leachability properties of the cemented soil A were better than those of the soil B.Sequential extraction procedures revealed that the chemical stability of Cd、Pb、As、Zn in cemented soil A were better than those of soil B.The acid soluble fractions of Cd,Pb,As and Zn in the cenemented A were converted to oxidizable fraction and residual.While the acid soluble fractions of Cd,Pb,As and Zn in soil B were converted to reducible fractions.The difference of solidification mechanism was the root cause of the differences in strength,leachability and speciation of soil A and B.
作者
贾世波
张学霞
李媛媛
JIA Shibo;ZHANG Xuexia;LI Yuanyuan(Qingdao University of Technology(Linyi),Linyi 273400,China)
出处
《工业建筑》
CSCD
北大核心
2019年第8期142-146,共5页
Industrial Construction
基金
国家自然科学基金项目(51409154)
山东省高校科研计划项目(J18KB059)
青岛理工大学(临沂)自然科学项目
费县科技创新项目
关键词
复合重金属污染土
碱激发水泥
强度
浸出
赋存形态
combined heavy metal contaminated soil
alkali-activated cement
strength
leachability
speciation
