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: 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 C2+ - JP to Ca2+-L bentonite caused increase in the geotechnical properties (liquid limit ivy, plasticity limit w(P), water adsorption by Enslin test E-S) compared to raw Ca2+ -L samples, but the parameters were still insufficient for sealing purposes of Ca2+-blends. After nitrification 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. (C) 2008 Elsevier Ltd. All rights reserved.