Effects of leachate on the hydraulic and mechanical behavoiur of clay liners

In addition to water content, degree of saturation, effective pressure and stress hostory, the hydraulic and mechanical behavoiur of clay also depends on its mineralogy and the chamical compounds of the pore-fluid. This fact is fundamentally due to ion exchange and mineral disoolution phenomena occurring between clayey minerals and cations existing withinthe fluid. This paper deals with a laboratory investigation on the behaviour of four different sand-bentonite mixture, alternatively permeated with water and leachate. A sodium bentonite and a calcium bentonite were used in order to emphasize the effects caused by different clay minerals. Fixed-wall permeability and oedometric compressione tests were carried out; the influences of void ratio, vertical effective pressure and permeant on hydraulic conductivity, compressibility and consolidation coefficients of clayey samples were investigated.