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The main purpose of this research is evaluation of effect of chemicals on permeability of sand- bentonite mixtures. The coefficients of permeability of sand- bentonite mixtures in water, solutions of sodium and calcium chlorides, sodium hydroxide, acetic acid, methanol and carbon tetrachloride were calculated using parameters obtained in 1- D consolidation test and Terzaghi’s theory. At each void ratio permeability of samples in water is the lowest and that for carbon tetrachloride is the highest. For all fluids the permeability index Ck is decreased as the percentage of sand is increased. The largest Ck belongs to the samples tested in water and the smallest Ck belongs to the samples tested in carbon tetrachloride.

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It introduced an innovative bioengineering method of consolidating incompact sand by urea-hydrolysis producing calcite cementation under the inducement of urease producing microbe. In the paper it discussed the effects of cementation methods and time on porosity and mechanical properties of microbe-inspired cementing sand columns. Method A adopted reaction fluid gravitational permeating and external pressing and method B adopted reaction fluid gravitational permeating and outlet intermittent plugging method. 28-day sand columns prepared by method A exhibited stronger mechanical properties than those prepared by method B, considering of the compressive strengths and three-point flexural strength as well. Pore volume fractions of sand columns prepared by method A reduced with an increase in cementation time which represented the bulk densities of sand columns were improved positively with time. The compressive strengths and the flexural strengths of sand columns prepared by method A increased with time. All these improved mechanical properties were attributed to the fact that the increasing amount of microbe inspired calcite precipitation with time consolidated sand columns by filling or bridging in sand gaps.