Feasibility of using CDW fine fraction and bentonite mixtures as alternative landfill barrier material

Construction and demolition waste (CDW) appear with potential application reused in sanitary landfills as alternative barriers, especially considering the use of its fine fraction. To fulfill literature requirements for landfill liners, the combination of CDW with bentonites appears as a feasible solution, while minimizes the use of natural resources and final CDW disposal problem. This paper describes the geotechnical performance of mixtures of CDW fine fraction with different contents of high-swelling sodium bentonite as well as chemical influence of curing time. Results showed that the plasticity of the mixtures was significantly increased with few bentonite contents. Compaction results were presented and unconfined compression strength results achieved minimum 200 kPa. Hydraulic conductivity drastically decreased with bentonite addition, reaching values of 10–9 m/s 16% bentonite content. A high increase in the CEC was observed in the CDW–bentonite mixtures, corroborating to material application in landfills. The presence of CDW fine fraction reduced the free swell index of bentonite. The curing period of 180 days showed to reduce swelling results, mainly due to the presence of calcium, magnesium oxide and pozzolana reactions. This research showed the feasibility of using CDW–bentonite mixtures as a landfill liner material.