污泥灰改性黏土胀缩与开裂变形特性

针对垃圾填埋场衬垫系统受污染物侵蚀破坏现状及污水处理厂剩余污泥回收处理利用工程评价问题,分析污泥灰改性黏土在酸碱化学溶液作用下胀缩与开裂特性,室内模拟酸碱化学溶液污染工况,将纯黏土与污泥灰掺量为1%~5%的改性黏土受pH=5、6、8、9的酸碱化学溶液污染,通过界限含水率试验测定改性黏土的液限与塑限,分析试样的稠度界限;通过膨胀与收缩试验测定改性黏土的膨胀率与收缩率,分析试样的胀缩特性;通过开裂试验测定改性黏土的开裂特性.结果表明:改性黏土液限约为43.5%,而随着污泥灰掺量增大,塑限升高,塑性指数降低,经酸碱化学溶液污染后污泥灰掺量5%的试样液、塑限达到最大,为45.9%、22.8%;污泥灰掺量为5%时膨胀率最低,为5.66%,掺量为3%时,线收缩率最低,为2.14%;受酸碱化学溶液污染后改性黏土膨胀率降低12.7%~36.5%,而线收缩率升高33.8%~75.7%;4次干湿循环后,纯黏土试样的开裂因子较第一次干湿循环末期大80.71%,而污泥灰掺量为3%试样开裂因子仅较第一次干湿循环末期大43.47%.故建议采用3%污泥灰掺量的改性黏土作为填埋场衬垫材料.

Swelling, shrinking and cracking properties of modified clay containing sewage sludge ash

In order to deal with the landfill liner which was corroded by pollutants and evaluate the feasibility of using the residual sludge in sewage treatment plant, tests were performed to analyze the swelling, shrinking and cracking properties of modified clay which contained 1%-5% sewage sludge ash (SSA) under the action of acid and alkali chemical solutions. pHs of chemical solutions used in the tests were 5,6,8,9 separately, and the conditions were simulated indoors. The liquid limit and plastic limit of modified clay were tested by moisture content test, and the consistency limit of samples was analyzed. The swelling rate and shrinking rate of modified clay were tested by swelling test and shrinking test, and the swelling and shrinking properties were analyzed. The cracking properties of modified clay were tested by cracking test. Based on the results of soil tests, the liquid limit of modified clay is about 43.5%. With the increasing of SSA contents, plastic limit increases and plastic index reduces, the maximum liquid limit and plastic limit of modified clay containing 5% SSA which is polluted by acid and alkali chemical solution are 45.9%, 22.8% respectively. The minimum swelling rate and shrinking rate are 5.66%, 2.14% of modified clay containing 5% SSA and 3% SSA respectively. Moreover, the swelling rate is reduced by 12.7%-36.5% and the shrinking rate is increased by 33.8%-75.7% when polluted by acid and alkali chemical solutions. After dry-wet circulation for four times, the cracking index factor (CIF) is 80.71% larger than that of the end of first dry-wet circulation of clay sample. However, it is only 43.47% larger than that of the end of first dry-wet circulation of modified clay containing 3% SSA. Thus, the modified clay can be used as landfill liner material and the best content of SSA is 3%.