Inclined Plane Shear Behaviour of a Recycled Construction and Demolition Material–Geocomposite Interface

Abstract

Over the years, recycled construction and demolition (RC&D) materials have become useful and valuable construction materials. The applications of these materials have been increasing, and there are cases where they may be in contact with geosynthetics. This work, which is part of a broader investigation into the feasibility of replacing soils used in landfill final cover systems by RC&D materials, analysed the inclined plane shear behaviour of the interface between a fine-grained RC&D material and a drainage geocomposite. Inclined plane shear tests were performed with different vertical stresses and different compaction conditions (degree of compaction and water content) of the RC&D material. The friction angle at the RC&D material-geocomposite interface was estimated by two approaches: the standard and the one based on the Mohr–Coulomb failure envelope. The sliding mechanism of the RC&D material over the geocomposite was examined. For comparison with the RC&D material-geocomposite interface, the behaviour of the RC&D material under inclined plane shear movement was also characterised. The main findings of the work included: the friction angle (standard approach) at the RC&D material-geocomposite interface decreased by increasing the applied vertical stress and the RC&D material water content (with meaningful changes in the slinging mechanism in the latter case), and tended to increase by increasing the degree of compaction of the RC&D material; the behaviour of the RC&D material under inclined plane shear movement did not differ significantly from that of the RC&D material-geocomposite interface; the failure envelope approach was more conservative (smaller friction angles) than the standard approach.