In traditional cushion of compacted clay mixed with 3%,5% and 7%( Relative to clay dry mass),the article explores the possibility of improving landfill compaction clay mats by chemical modification of sludge ash.The adsorption capacity of Cu( Ⅱ) was studied by isothermal adsorption experiment. The results show that the addition of sludge ash greatly improves the saturated adsorption capacity of the sample,and the adsorption capacity of Cu( Ⅱ) is obviously enhanced. When the sap ash content varied from 3% to 7%,the saturated adsorption capaci...