Abstract：The membrane behavior of soil bentonite(SB) vertical cutoff wall backfills is important in evaluating the contaminant containment performance of the SB vertical cutoff walls. Lead nitrate(Pb(NO3)2) solutions with various concentrations were tested as testing liquids for a multi-stage chemico-osmotic soil column test to assess chemico-osmotic efficiency coefficients，effective diffusion coefficients and retardation factors of polyanionic cellulose(PAC) amended bentonite/sand(PSB) and unamended SB backfills. The results showed that the measured chemico-osmotic efficiency coefficients of PSB and unamended SB backfills decreased with increasing Pb(NO3)2 concentration. The measured chemico-osmotic efficiency coefficient of the backfill in the Pb(NO3)2 solutions was enhanced with PAC amendment，which was about 2–3 times of that of unamended SB backfill. The effective diffusion coefficients of PSB and unamended SB backfills increased with increasing source Pb(NO3)2 concentration，whereas the retardation factors of lead reduced with increasing Pb(NO3)2 concentration. Compared with unamended SB backfills，PSB backfills possessed lower effective diffusion coefficient and higher retardation factor at a given Pb(NO3)2 solution.
2020, Vol. 39 
