An Experimental Study on the Interface between a Waterproofing Membrane in Contact with Dry and Saturated Sand

Wherever a hydraulic barrier is required, waterproofing membranes are often employed in construction. Because they sit at the boundary between the natural and built environments, interface modeling is an important part of their assessment. This highlights the value of maintaining an experimental test database on the behavior of waterproofing membranes in contact with various soils and environmental conditions. This study is part of a series of large-scale laboratory tests on soil-structure interactions focused on the friction mechanism at various interfaces with boundary conditions as similar to reality as possible. The aim of this paper is to investigate the interface shear resistance of the waterproofing membrane interface in contact with dry and saturated Ottawa sand. To this end, a spray-applied waterproofing membrane was sheared on Ottawa sand placed in a sandbox with interior plan dimensions of 305 x 305 cm and an interior height of 100 cm. The coefficient of sliding friction at the interface is characterized, and the surface failure mechanism is also discussed. The waterproofing membrane-sand interface friction angle was found to be independent of normal pressure and quite different from the internal friction properties of the Ottawa sand. It was observed that the shear resistance at the interface of saturated sand was greater than its dry counterpart. The data sets are being used to support the development of numerical models for sliding at waterproofing membrane-soil interfaces.