Effects of leaching parameters on swelling behaviors of compacted mudstone used in landfill liner.
This study attempt to determine the swelling deformation of compacted mudstone using the free swell test, and the leaching parameters using a pH meter, a conductivity meter, and ion chromatography (IC) techniques. Closely examining chemical characteristics indicated that natural mudstone is saline-alkali soil. The maximum swelling deformation obtained from the free swell test is about 15.7%. The swelling developed relatively rapidly after the start of soaking, stopping after 7 days. The leaching characteristics in compacted mudstone involve the hydrolysis of Na+ ions, the precipitation of CaCO3 and slightly dissolution of Mg2+ ion. The relationship of swelling deformation to sodium adsorption ratio (SAR) value indicated that the SAR value in soaking suspension significantly affects the amount of swelling. Additionally, the pH of the soaking suspension importantly affects swelling behavior. Overall, the early swelling behaviors of compacted mudstone are posited to involve directly the concentration of Na+ ions in the soaking suspension and the precipitation of CaCO3 in compacted mudstone. Furthermore, the very slight swelling after the 3-day soaking is related to the dissolution of Mg2+ ions in compacted mudstone.
Chen
Hung-Ta
HT
Department of Environmental Engineering, National Cheng Kung University, Tainan, Taiwan, ROC.
Lin
Tzong-Tzeng
TT
Chang
Juu-En
JE
D000538:Aluminum Silicates; D011232:Chemical Precipitation; D000077215:Clay; D004560:Electricity; D019015:Geologic Sediments / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D012037:Refuse Disposal; D012989:Soil Pollutants / Q000032:analysis*; D014876:Water Pollution / Q000517:prevention & control*
D000538:Aluminum Silicates; D012989:Soil Pollutants; D000077215:Clay