EFFECT OF CLAY MINERALOGY AND ALUMINUM AND IRON-OXIDES ON THE HYDRAULIC CONDUCTIVITY OF CLAY-SAND MIXTURES

Changes in hydraulic conductivity and clay dispersivity of clay-sand mixtures (four reference smectites and Fithian illite) as a function of concentration (0. 01 M Cl** minus and distilled water) and sodium adsorption ratio (SAR) of the percolating solution were measured. In addition, the effect of sand percentage, sand particle size, and addition of AlCl//3 and FeCl//3 on the hydraulic conductivity of the mixtures were measured. Clay dispersion and migration out of the 3% clay columns was substantial. Mixtures treated with FeCl//3 and AlCl//3 were leached with NaCl-CaCl//2 solutions until the pH of the effluent exceeded 6. 5. The composition of the exchangeable phase was then determined by the SAR of the leach solutions. Study results are discussed in the paper. Refs.