An alternative capillary landfill cover system based on sewage dewatering sludge, construction waste, and Ca‐bentonite

Abstract This study prepared an innovative capillary barrier cover material (CBM) composed of sewage dewatering sludge, construction waste, and Ca‐bentonite, and designed a four‐layer capillary barrier landfill cover system. The engineering mechanical characteristics of the CBM were detected using unconfined compression tests and triaxial shear tests, and the water‐holding capacity and hydraulic conductivity of the CBM were tested through soil–water characteristic curve tests and permeability tests. A rainfall model assessed water seepage in the capillary barrier landfill cover system. The water‐holding capacity of the CBM was found to be equivalent to that of silty clay, and the hydraulic conductivity was 2.06 × 10 −6 –1.41 × 10 − 4 cm/s. No rain leakage occurred at the bottom of the capillary barrier cover system during a rainstorm and heavy rainstorm. This was mainly attributed to the covering material storing rainwater in the pores via the capillary block effect, and the stored water then dissipating through evaporation. This study provides data support for the design and popularization of a capillary barrier landfill cover system in the middle reaches of the Yangtze River. However, the material ratio of the capillary barrier layer should be adjusted according to the source of construction waste and municipal dehydrated sludge.