An investigation into the use of blends of two bentonites for geosynthetic clay liners

Enhancement of geotechnical parameters of Fe-rich bentonite of lower smectite content (L: Lieskovec, Slovakia; 28–56% montmorillonite) by addition of an Al-rich bentonite of higher smectite content (JP: Jelšový potok, Slovakia; 64% montmorillonite) is discussed. The blends of different L and JP contents (L:JP 85:15, 75:25, and 65:35 mass%) were investigated. Addition of more expensive Ca2+-JP to Ca2+-L bentonite caused increase in the geotechnical properties (liquid limit wL, plasticity limit wP, water adsorption by Enslin test ES) compared to raw Ca2+-L samples, but the parameters were still insufficient for sealing purposes of Ca2+-blends. After natrification of the blends with soda ash, the geotechnical parameters markedly improved. Permeability coefficients of all the blends were satisfactorily low, of the order of 10−11 m s−1. The liquid limit and water absorption values of the blend containing 65 mass% of Na+-L and 35 mass% of Na+-JP bentonites meets the requirements on geotechnical parameters of bentonites used in GCLs. Smectite content in the blends is the dominant factor affecting their properties.