Engineering benefits of replacing natural sand with manufactured sand in landfill construction

Translational sliding failures in landfills are often triggered by inadequate shear strength of interfaces in liners and covers. Geosynthetic Clay Liners (GCL) are used in different components of landfills to contain the leachate. GCLs are usually placed above a compacted sand subgrade to develop higher shear resistance. In the context of depleting natural sand resources, the present study explores the feasibility of replacing natural sand with manufactured sand (Msand) in landfill construction. Interface shear tests were performed on GCL in contact with river sand and Msand of similar gradation to evaluate the shear strength at different normal stresses and hydration conditions. It is found that Msand provides higher interface shear strength with GCL compared to river sand. Digital image analysis of tested specimens of GCL showed that variation in particle morphology of the two sands has direct influence on the microlevel interaction mechanisms governing the shear strength. Quantification of morphological parameters showed that Msand particles are angular and rough compared to natural sand particles, leading to higher particle interlocking. Hydration of the GCL reduced the interface shear strength, the effect being less in case of Msand. The study highlights that replacement of natural sand with Msand has added benefits.