Effects of temperature and material thickness on the diffusion properties of bituminous geomembranes (BGMs) in waste...

The diffusion behaviour of four elastomeric bituminous geomembranes (BGMs) from two manufacturers and with different thicknesses is investigated to assess the effects of temperature, thickness, and formulation on their performance as diffusive barriers for solid waste containment applications. All BGMs examined had a 0.012 mm anti-root polyester (PET) film at their bottom surfaces. Diffusion tests are conducted on the as-received BGMs and the BGM components (the isolated PET film, and a modified BGM sample obtained by removing the PET film from the as-received material) at 24 °C, 35 °C and 50 °C. The diffusion parameters inferred at the three test temperatures were used to generate theoretical concentration profiles, which closely matched the experimental data, thereby validating the use of a two-layer modelling approach that treats BGMs as a multilayer composite material. Results demonstrated a clear increase in the diffusion of volatile organic compounds (VOCs) with temperature through the as-received BGM and its different components, with the PET film providing the main resistance to VOC migration. Additionally, it is shown that thicker BGMs exhibited longer times to equilibrium, consistent with a reduced rate of permeation resulting from extended diffusion pathways. However, BGMs from the same manufacturer exhibited comparable diffusion parameters regardless of thickness. These findings highlight the need for material-specific composition testing in diffusive performance assessments. They also show the key role of temperature and the PET film in controlling the VOC migration through BGMs in containment barrier systems.