A Pollutant transport investigated through an expansive

In the framework of domestic waste disposals, the in-situ compaction of soil is usually used to obtain engineered clay barriers with suitable confining properties. Permeability and pollutant retention are the major properties which should be investigated in this context for barrier evaluation. Considering clay barriers in contact with waste leachates, they may be saturated by solutes of various chemical compositions, including in particular toxic heavy metals. In this context, the expansive Fo-Ca clay, a natural Ca-smectite from the Paris basin of Ypersian (Sparnacian) age, was chosen because of its very low permeability and ability for pollutant retention through cationic exchanges. The smectic is associated with kaolinite (up to 20%), and minor quartz, calcite, goethite and gypsum. An experimental work (JULLIEN et al., 2002) was performed to analyse the Fo-Ca performances when submitted to chemo-hydro-mechanical coupled effects produced by soaking the clay with a polluted solute. For this purpose, tests were performed using 10-1 mol/l Cu(NO3)2 solution. The evolution of leachate chemical composition was carried out as a function of time in order to characterise the ability of the clay to copper retention (fig 1). The previous studied clay samples can be considered as a system submitted to an externa