垃圾填埋场污泥灰改性黏土衬垫的强度特性及微观结构

Strength properties and microstructure of landfill clay liner containing sewage sludge ash

为评价污泥灰改性黏土作为填埋场衬垫防渗材料的可行性,分析污泥灰改性黏土强度特性及孔隙结构,针对受垃圾渗沥液腐蚀的纯黏土与污泥灰掺量为1%~5%的改性黏土,采用直接剪切试验分析其抗剪强度变化规律,采用低温氮气吸附试验分析剪切变形后试样的孔隙结构组成。结果表明,改性黏土属于VI型等温线,并存在H3型滞后环,且2~6 nm介孔的数量占比较大。受垃圾渗沥液腐蚀后,黏土抗剪强度大幅下降,黏聚力与内摩擦角分别下降60.12%和19.17%;黏土的最大氮气吸附量降低16.19%,且孔隙分布双肩峰发育不完全;随污泥灰添加量的增加,改性黏土抗剪强度增大,且孔隙分布逐渐恢复双肩峰形式,总孔容增大。

In order to evaluate the feasibility of improved clay based on sewage sludge ash(SSA) used as landfill liner-soil materials, a series of the direct shear strength tests and low temperature nitrogen adsorption tests were carried out to analyze shear strength and pore structure of improved clay in laboratory. The improved clay was composed of 95%-99% of raw clay and 1%-5% of SSA. The results show that the isotherms of improved clay containing SSA is belong to type VI isotherms, and it had type H3 hysteresis loop; The pore of improved clay was mainly composed of mesopore of 2-6 nm. The shear strength of raw clay corroded by landfill leachate sharply decreased. The cohesive strength and internal friction angle of sample declined 60.12% and 19.17%, respectively. The maximum adsorption capacity of raw clay corroded by landfill leachate declined 16.19%. The shear strength and pore volume of improved clay increased with an increasing of SSA.