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| Hydraulic conductivity of filter cakes of polyanionic cellulose-amended bentonite slurries in calcium chloride solutions |
| SHEN Shengqiang1，2，DU Yanjun1，2，WEI Mingli3，XUE Qiang3，YANG Yuling1，2 |
(1. Institute of Geotechnical Engineering，Southeast University，Nanjing，Jiangsu 210096，China；2. Jiangsu Key Laboratory of Urban Underground Engineering and Environmental Safety，Southeast University，Nanjing，Jiangsu 210096，China；3. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China)
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Abstract The incompatibility between the bentonite and inorganic solutions has adverse impact on the impermeability of the filter cakes and backfills in soil-bentonite slurry walls. To improve the hydraulic performance of bentonite were backfills exposed to inorganic solutions，the Polyanionic Cellulose(PAC) and sodium activated bentonite were directly blended to produce a polymer-amended bentonite termed as PB. The Calcium Chloride(CaCl2) solutions were selected as the test solutions，and the hydraulic conductivities of the bentonite filter cakes to distilled water(kw) and to concentrated CaCl2 solutions(kc) were measured through modified filtrate loss tests under various applied pressures. The results indicate that the kc of PB filter cake increases with the increase in CaCl2 concentrations，whereas the filtrate loss volumes(V) of PB specimens remains less than the standard limits(25 mL). The hydraulic conductivity of PB is lower than that of CB in the range of CaCl2 concentration used in the study. The water contents(w) of both filter cakes decrease with the increasing of CaCl2 concentration for a given average effective pressure，which results in the decreasing in the void ratio of filter cakes and increasing in the kc of both filter cakes. The increasing of average effective pressure can partially counteract the adverse effect on kc caused by the increasing of CaCl2 concentration. The hydraulic conductivity ratio(kc/kw) of the PB filter cake is less than 10 when the CaCl2 concentration is no more than 60 mM，illustrating that the kc of PB filter cake has no significant increasing. Therefore，mixing PAC with bentonite can improve the hydraulic performance effectively.
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2017, Vol. 36 
