Impact of manufacture method on the hydraulic performance of polymer-enhanced calcium bentonites
Sodium polyacrylate amended Ca-bentonites(PAAS-CaBs)were prepared by dry mixing,wet mixing,wet kneading and in-situ polymerization.The hydraulic properties of polymer enhanced bentonites under acidic mine drainage solution(AMD)were investigated by swell index and modified fluid loss tests.When tested with AMD,values of swell index,fluid loss and hydraulic conductivity of PAAS-CaBs prepared by dry-mixing,wet-mixing and wet-kneading increased by factors of 1.1～4,2.7～5.3,and 1.4～2.4,respectively,whereas that of PAAS-CaBs prepared by in-situ polymerization increased by a factor of 4 and decreased by 30％and 97％,comparing to the unamended CaBs.In general,the hydraulic properties of polymer enhanced bentonites under AMD solution deteriorate in the following order:in-situ polymerization＞wet-kneading＞wet-mixing＞dry-mixing.The dry-mixing method is recommended for scenarios with mild contamination and limited budget,whereas the in-situ polymerization method is recommended for scenarios with severe contamination and high-level criteria of pollution control.
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