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

摘要

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: Jelsovy 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 Ca~(2+)-JP to Ca~(2+)-L bentonite caused increase in the geotechnical properties (liquid limit W_L, plasticity limit w_P, water adsorption by Enslin test E_s) compared to raw Ca~(2+)-L samples, but the parameters were still insufficient for sealing purposes of Ca~(2+)-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 35mass% 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.