Migration of aggressive solutions through cement-bentonite slurry walls

Migration parameters and interaction of saline solutions through cement-bentonite cutoffs

“…It is important to point out that, for CB mixtures, the sorption isotherms of K + and SO4 2from batch tests were found to be in good agreement with the sorption isotherms by column tests (Fratalocchi et al, 2013) which better simulate the in situ migration conditions. Fig.…”

“…where kf [L 3 M -1 ] and  [-] are constant. For the CB mixture, sorption of SO4 2decreases with curing, due to the decrease in porosity and in the mean void size of the mixtures (sorption sites tend to be less accessible with curing; Fratalocchi et al, 2013). For the same reason, sorption of SO4 2by the special mixtures results lower than that of the CB mixture and independent of the curing time (Fig.…”

“…Both the CB mixture and the special ones match the practical requirements (Table 1). The mixtures were poured in PVC cylindrical moulds (prepared to avoid sample disturbance during extraction, Fratalocchi et al, 2013) and stored under tap water until the curing time of testing. The testing solutions were tap water for the hydraulic conductivity tests and aqueous solutions of K2SO4, resulted almost neutral (pH in the range of 6.8-7.3, increasing with the concentration of K2SO4).…”

“…Tests were performed to verify that this choice would has not influenced the results ( § 3.2). A contact time of at least 48 hours was guaranteed for chemical equilibrium (Fratalocchi et al, 2013). The adsorbed mass, ma, was calculated as the difference between the initial and final mass of solute in solution, the adsorption ratio, S, as the ratio between ma and the dry mass of the sample, ms.…”

“…Much literature dealt with hydraulic conductivity of traditional cement-bentonite mixtures (e.g. Manassero et al, 1995; Opdyke and Evans, 2005; Jefferies, 2012), whereas few data and researches are documented about diffusion (Visudmedanukul et al, 2007;Fratalocchi et al, 2013), sorption and chemical interaction (e.g. Jefferis, 2003;Soga and Joshi, 2010;Soga et al, 2013).…”