In order to study the feasibility of modified sewage sludge as landfill cover material and its performance in a complex landfill environment, strength and hydraulic conductivity tests were conducted. The permeability requirements for daily and interim covers were analyzed first. Based on saturated-unsaturated seepage calculations, it is suggested that approximately 1.0×10^-4 cm/s and 1.0 × 10^-5 cm/s are the appropriate values for the hydraulic conductivities of daily and interim covers, respectively. The strength and permeability requirements of the mixtures, when used as an interim cover, can be met at a sludge：lime：cement：silt：tire-derived aggregate （TDA） weight ratio of 100：15：5：70：15. Results also demonstrate that the solid content ratio of modified sewage sludge, which should be greater than 60% when modified sewage sludge is used as a temporary cover material, is crucial to both strength and hydraulic performance. In addition, as the duration of soaking of modified sewage sludge in synthetic leachate increases, the unconfined compressive strength increases, and the hydraulic conductivity decreases slightly or fluctuates between 1.0×10^-5 cm/s and 1.0 × 10^-6 cm/s, still meeting the requirements for an interim cover. The reduction in hydraulic conductivity of modified sewage sludge under the effect of synthetic leachate, as well as the long-term and environmental performance of the modified sewage sludge, should be examined in future studies.
废旧轮胎胶粉用于填埋场衬垫材料改性,有望提高衬垫系统的有效性并扩展废旧轮胎的资源化利用途径。开展废旧轮胎胶粉–黏土混合土的内部强度和界面强度试验,探讨胶粉特征对混合土强度性质的影响规律。研究表明,随着胶粉掺入比的增加,混合土抗剪强度有所增大,无侧限抗压强度满足规范要求。当掺入比为15%,土工膜/混合土界面强度高于土工膜/高岭土,但400 k Pa压力下表现出软化特征,残余强度低于土工膜/高岭土界面;与GCL/高岭土界面相比,GCL/混合土界面强度在法向应力较小时略小,但在法向应力较大时显著增大;界面强度小于土的内部抗剪强度。总体来看,12和30目胶粉对混合土强度的影响没有显著差异,高岭土中掺入废旧轮胎胶粉不会对内部强度和界面强度产生不利影响。
