The study of earthen barriers or clay liners has become very important in the field of geo-environmental engineering. The design of clay liners is based on the fact that leachate migration through clay liners depends on their hydraulic conductivity (k). Hence, a low hydraulic conductivity (k) is an important parameter in the design of clay liners. Compacted expansive clays or montmorillonite clays have a very low hydraulic conductivity. When expansive clays or montmorillonite clays are blended with fly ash (which is stabilization of the clay with fly ash), an industrial waste, the hydraulic...