Hydration effects on the mechanical performance of GCLs looked through the lens of particle morphology

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4. Hydration effects on the mechanical performance of GCLs looked through the lens of particle morphology

The present study brings out the role of particle shape on the hydration effects in GCLs through image-based particle shape characterizations, shear tests on sand-GCL interfaces and surface analysis of sheared GCLs. Two different sands with distinct particle shape, a rounded sand and an angular sand were chosen for the study with a wide variation in their shape parameters. Roundness, sphericity, and normalized roughness of the particles were quantified through digital imaging and MATLAB computations. Shear tests were carried out on sand-GCL interfaces in dry and saturated conditions under a wide normal stress range. It was observed that GCLs in contact with angular sands get less hydrated compared to the GCLs in contact with rounded sand because of the reduced permeability and increased tortuosity in angular sands. Image analysis of surfaces of exhumed GCL specimens revealed that the amount of sand trapped on the GCL surface varied with the particle shape, leading to the differences in their performance at large strains. The particle shape parameters, micro-scale kinematics at the interface and microscopic surface changes to the GCL surface are correlated to the macroscopic interface shear strength while understanding the hydration effects in GCL. The study highlights the importance of understanding the particle morphology in reducing the hydration effects in GCL while designing landfill systems.  

9th International Congress on Environmental Geotechnics (ICEG2023)

Advances in Testing and Material Characterization