冻融作用下水泥固化煤化工废水污染土的强度特性及微观结构

Strength Characteristics and Microstructure of Cement-solidified Coal Chemical Wastewater Contaminated Soil under Freeze-thaw Action

为了解水泥固化煤化工废水污染土的强度特性及微观结构,以凹凸棒土为外掺剂,通过室内试验的方法研究了冻融循环作用下固化土的无侧限抗压强度、质量损失率及T2谱分布曲线。结果表明:养护28 d后,随外掺剂掺量增加,固化土的强度逐渐降低;随冻融循环次数增加,固化土的强度先增长后降低;掺加外掺剂固化土相比无外掺剂固化土,其强度明显降低;掺加外掺剂、无外掺剂和无苯酚无外掺剂三类固化污染土的累计质量损失率随循环次数的增加而增大,且呈相似的变化规律;在冻融循环3次时,固化土的孔隙减小且孔径变小,冻融循环5次和10次时,固化土的孔隙增加且孔径变大。由此可见,凹凸棒土虽使固化土强度降低,但因特殊的性质,对污染物的固化稳定化效果增强;固化土的强度变化与其内部孔隙和孔径有关。

In order to understand the strength characteristics and microstructure of cement-cured coal chemical wastewater contaminated soil,attapulgite soil was used as admixture to study the unconfined compressive strength,mass loss rate and T2 spectrum distribution curve of solidified contaminated soil under freeze-thaw cycle by laboratory test.The results show that after curing for 28 days,the strength of solidified soil decreases gradually with the increase of the amount of admixture.With the increase of freezing-thawing cycle,the strength of solidified soil first increased and then decreased.The strength of solidified soil with admixture decreased significantly compared with that without admixture.The accumulative mass loss rate of the three types of solidified contaminated soil with admixture,without admixture and without phenol and without admixture increases with the increase of cycle times,and presents similar change rules.When the freezing-thawing cycle was repeated for 3 times,the pores of the solidified soil decreased and the pore diameter decreased;when the freezing-thawing cycle was repeated for 5 times and 10 times,the pores of the solidified soil increased and the pore diameter increased.It is concluded that although attapulgite reduces the strength of solidified soil,its stabilization effect on pollutants is enhanced due to its special properties.The strength of solidified soil varies with its internal pores and pore size.