摘要
为评估矿渣-水泥-膨润土(slag-cement-bentonite,简称SCB)和氧化镁激发矿渣-膨润土(magnesium oxide activated slag-bentonite,简称MASB)两种自硬化材料作为Cr(Ⅵ)污染场地竖向屏障的工程可行性,研究了SCB和MASB试样在K_(2)CrO_(4)溶液作用下工程性能和微观结构的演化规律。首先,对浸泡试验后试样的质量、外观、变色层厚度、无侧限抗压强度和渗透系数变化情况进行测定。随后,基于宏观试验结果对部分试样开展了X射线衍射(X-ray diffraction,简称XRD)、扫描电子显微镜(scanning electron microscope,简称SEM)、傅里叶红外光谱(Fourier transform infrared spectroscopy,简称FTIR)和元素形态顺序提取等微观测试。结果显示,SCB和MASB试样的质量以及变色层厚度均随浸泡时间和污染液浓度的增加而增大,其主要原因在于CaCrO_(4)和MgCrO_(4)等物质的生成及试样中CrO_(4)^(2-)的物理吸附。SCB和MASB试样的无侧限抗压强度随浓度增大而降低,渗透系数则随之增大而增大。当污染液浓度为0.5 mol/L时,SCB和MASB试样的强度分别降低42%和60%,渗透系数分别增大超过10倍和100倍,这主要是由于在K_(2)CrO_(4)溶液作用下,水化产物生成量减小,试样致密性降低。综合分析表明,尽管SCB和MASB两种自硬化材料在自来水下具有较好的工程性能,但其与K_(2)CrO_(4)溶液的化学相容性差,易因Cr(Ⅵ)污染液作用而劣化。因此,当污染场地内Cr(Ⅵ)浓度较大时,两种材料均无法直接满足使用要求,需开展改性研究。
Aiming at evaluating the engineering feasibility of two self-hardening materials,slag-cement-bentonite(SCB)and magnesium oxide activated slag-bentonite(MASB),as vertical barriers for Cr(Ⅵ)-contaminated sites,the evolutions of their engineering properties and microstructures under the effect of K_(2)CrO_(4)solution were investigated.Firstly,the changes in mass,appearance,thickness of the discoloration layer,unconfined compressive strength and permeability coefficient of the specimens after the immersion test were determined.Subsequently,based on the results of the macroscopic tests,some specimens were subjected to microscopic tests such as X-ray diffraction(XRD),scanning electron microscope(SEM),Fourier transform infrared spectroscopy(FTIR)and elemental morphology sequential extraction.The results indicated that the masses of SCB and MASB specimens as well as the thickness of the discoloration layer increased with the increase of immersion time and the concentration of contaminated solution.This is mainly due to the generation of substances such as CaCrO_(4)and MgCrO_(4),as well as the physical adsorption of 24 CrO-within the specimen.The unconfined compressive strengths of SCB and MASB specimens decreased with an increasing concentration,while the permeability coefficient increased with it.When the concentration of the contaminated solution reached 0.5 mol/L,the strengths of SCB and MASB specimens decreased by 42%and 60%respectively,while the permeability coefficients increased by more than 10 and 100 times respectively,which was largely due to the decrease in the generation of hydration products and the reduction of specimen densification under the effect of K_(2)CrO_(4)solution.Comprehensive analysis revealed that although the two self-hardening materials,SCB and MASB,had good engineering performance under tap water immersion,their chemical compatibility with K_(2)CrO_(4)solution was poor,and they were easy to deteriorate due to the effect of Cr(Ⅵ)contaminated solution.Therefore,when the concentration of Cr(Ⅵ)in the contaminated site reaches a large level,both materials can not directly meet the requirements for use,and modification studies need to be carried out.
作者
程鑫
江文豪
黄啸
李爽
王应富
李江山
CHENG Xin;JIANG Wen-hao;HUANG Xiao;LI Shuang;WANG Ying-fu;LI Jiang-shan(Institute of Rock and Soil Mechanics,Chinese Academy of Science,Wuhan,Hubei 430071,China;University of Chinese Academy of Sciences,Beijing 100049,China;Guilin University of Technology,Guilin,Guangxi 541004,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2024年第S01期225-238,共14页
Rock and Soil Mechanics
基金
国家重点研发计划课题(No.2019YFC1804002)
作者简介
第一作者:程鑫,男,1999年生,硕士研究生,主要从事环境岩土和污染场地防控方面的研究。E-mail:chengxin212@mails.ucas.ac.cn;通讯作者:李江山,男,1987年生,博士,博士生导师,研究员,主要从事污染场地工程修复和固废资源化方面的研究。E-mail:jsli@whrsm.ac.cn
