Effects of the Organic Fluid Concentration on the Permeability of the Sand-Bentonite Mixtures

• Main Authors: Jien-Lin Huang, 黃建霖
• Other Authors: Jen-Chen Fan
• Format: Others
• Language: zh-TW
• Published: 1994
• Online Access: http://ndltd.ncl.edu.tw/handle/92782765408536018454

碩士 === 國立臺灣大學 === 農業工程學系 === 82 === Because of low permeability, clays are often used as liners or barriers to prevent pollutants from getting into the nature. However, after contaminated by organic fluid, permeabilities of the clays may be changed. In this study, methanol and ethanol with different concentrations were used as permeant, and sand- bentonite mixture which was well compacted was the soil used in the permeability test. Effect of the ratio of bentonite to sand by mass weight in the mixture on permeability was also studied. Permeability tests were conducted using a set of automatic triaxial flexible wall permeameter to avoid side leakage. Test results show that the permeabilities of the soils using any concentrations of methanol and ethanol as permeants are even lower than those using water as the permeant. When the concentrations of methanol and ethanol are from 40% to 70%, the permeabilities had a minimum value. When the ratio of bentonite to sand (B/S) is as low as 10%, and the mixtures are well mixed and well compacted, the soils are at the optimum conditions in view of the permeability. Under this condition, the whole sys- tem is mainly supported by the sand particles. Therefore, the stability of the system may be insured and the shrinkage of the system may be effectively controlled. After analyses of economic efficiency and marginal benefit, it is found that sand-bentonite mixtures are better than kaolinite when cost and economic effects are considered. Besides, correlations between permeability and viscosity, dielectric constant of the fluid, void ratio of the mixture and B/S, were derived. Its coefficient of determination is found to be as high as 0.943.