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The shear strength of particulate material–smooth geomembrane interfaces results predominantly from ploughing and/or sliding of the particles at the interface. The relative contribution of particle sliding and ploughing for a given smooth geomembrane surface is principally a function of relative material hardness, particle angularity, and normal stress. The relative material hardness is ambient temperature dependent since the geomembrane is polymer based. When ploughing occurs at any temperature, the geomembrane surface wears, resulting in altered surface topography and different interface strength. This paper summarises the results of a study that quantified changes in the surface roughness of geomembranes as a function of ambient temperature, normal stress, and particle angularity. Surface roughness measurements were made on both virgin and post-shear smooth geomembrane specimens using a stylus profilometer to quantify the extent of wear resulting from shearing against different counterface materials at different temperatures under different normal stresses. Increased ambient temperature and particle angularity significantly increased the geomembrane surface roughness and provided quantitative insight into the wear mechanisms at granular material–smooth geomembrane interfaces.

Temperature is one of many important environmental variables that can impact the long-term performance, strength, and deformation characteristics of many man-made construction materials, including geosynthetics. The functional engineering properties of these materials must remain within acceptable limits during their service life to ensure that the overall design and performance are acceptable. In the case of geosynthetics used in landfills and other applications, laboratory interface shear tests are performed under standard test conditions, including temperature. Information emerging today shows that geosynthetic interfaces (i.e., in landfill liner applications) experience elevated temperatures resulting from exothermic reactions occurring in the waste body, amongst other factors. To this end, the field conditions at elevated temperatures should also be simulated in the laboratory during physical/mechanical laboratory tests in order for researchers to better understand in situ functional engineering properties and operational performance of manmade geo-construction materials. For this purpose, a temperature-controlled chamber was designed and developed to allow the shear behavior of geosynthetic–geosynthetic and soil–geosynthetic interfaces to be evaluated at different temperatures. This paper describes both the development and the validation of the test system. The results of experimental investigations are presented to illustrate how the shear behavior of interfaces between nonwoven polypropylene geotextile and smooth and/or textured high density polyethylene geomembrane, as well as those between rounded and/or angular sand and geomembranes, change with temperature. The results provide insight into the importance of being able to independently control this variable during mechanical testing in the laboratory.