Effect of Bentonite Content on Hydraulic Conductivity of Sand-Bentonite Mixtures Used in Landfill Liners as an Alternative to Clay Liner in Egypt

Abstract Compacted clays are commonly utilized as landfill liners due to their impermeable properties, however, the availability of natural clay soil may be difficult or prohibitively expensive in some regions thanks to the expense of transportation, the local soil availability or regulation. As an alternative hydraulic barrier, a compacted mixture of sand with a low percentage of bentonite (6% to 14%) was used. The purpose of this research is to investigate the applicability of bentonite available in the Egyptian market for controlling the hydraulic conductivity of sand-bentonite mixtures to be used in landfill liners. The study was divided into two phases: first, laboratory tests were conducted to identify the optimum bentonite percentage and bentonite types, using local commercial bentonite products. Then, in two distinct landfill liners layers, full-scale measurements were obtained. The experimental program demonstrated that Bentonite produced and found in the Egyptian market can be utilized in landfill liners with an acceptable quality control procedure to prevent any outcome deviation.