Effect of salt of various concentrations on liquid limit,and hydraulic conductivity of different soil-bentonite mixtures |
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| Authors: | Anil Kumar Mishra Masami Ohtsubo Loretta Y Li Takahiro Higashi Junboum Park |
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| Institution: | (1) Department of Civil and Environmental Engineering, Seoul National University, Seoul, 151-742, South Korea;(2) Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan;(3) Department of Civil Engineering, The University of British Columbia, Vancouver, V6T 1Z4, Canada |
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| Abstract: | Effect of the various concentrations of NaCl and CaCl2 on the four different soil-bentonite mixtures has been evaluated. The results show that the liquid limit of the mixtures
decreases with an increase in the salt concentration. Liquid limit decreased significantly with an increase in CaCl2 concentration from 0 to 0.1 N. However, a further increase in the concentration did not produce any significant decrease
in liquid limit. A quite opposite trend was observed for the NaCl solution. An increase in NaCl concentration from 0 to 0.1 N
did not produce any major decrease in the liquid limit, but a further increase in concentration from 0.1 to 1 N decreased
the liquid limit significantly. Consolidation tests were carried out on the mixtures to evaluate the effect of mineralogical
composition of the bentonite on the hydraulic conductivity (k) of the mixture in the presence of various salts concentrations. The k for any mixtures was found to be decreasing with decrease in the salt concentration. At relatively low concentration, Ca2+ had more effect on the k in comparison to the same concentration of Na+. However, at 1 N of NaCl and CaCl2 almost an equal value of k was observed. A comparison of the performance of four bentonites showed that the mixture with bentonite having highest exchangeable
sodium percentage (ESP) exhibited the lowest k when permeated with de-ionized (DI) water, however, k increased with an increase in the salt concentration. Similarly, mixture with a bentonite of lower ESP exhibited a higher
k with DI water but with the increase in the salt concentration alteration in the k, compared to all other mixtures, was relatively less. |
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| Keywords: | Bentonite Mineralogical properties Swelling Liquid limit Hydraulic conductivity |
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