The Effect of Mixing Method on the Permeability Changes of Cement—Bentonite (original) (raw)

In researches conducted on various materials to stabilize soils, different factors have been investigated but none of the researches conducted has focused on method of incorporation or mixing. Hence, in this study the effect of cement—bentonite incorporation method with both wet and dry methods in 14.7 and 28 curing time will be studied to show its effect on the permeability coefficient changes. The results obtained in this study showed that the effect of incorporation is visible in all samples, so that most of the samples, which were prepared dry, the slope of their e-Log k curve is less than the wet samples which shows the sensitivity of wet samples to dry samples due to permeability coefficient changes .The results of this study can be used in preparing the underground waste storage tanks. Introduction The permeability coefficient is an important factor in the field of hydrology, this parameter can be used in groundwater management, supporting and maintaining groundwater and groundwater source management, Therefore the behavior of stabilized soils in terms of permeability of water in soil is significantly important. If the mixed stabilized soil has high permeability to water, where it is used for excavation or construction projects, the movement of water in the soil increases. Scrolling wheel and continuous loading and unloading of the traffic in the soil will have a performance similar to the pump .The movement of water in soil breaks the interlocks between stabilized soil seeds and resistance to speed decreases. If there is water, silicates and calcium aluminates of cement form hydrated compounds that in itself create hardened cement paste with high strength, which retain in themselves the materials mixed with cement. The hydration reaction, due to moving from cement particle surface, is slow and even the center of the particle may not get hydrated, Therefore the hydration process is constantly reducing which shows the reason for rapid reduction in the strength acquisition process by time in the materials stabilized with cement. Formation or lack of bond between hardened cement structure and particles of stabilized materials depend on chemical composition of the materials (Castelbaum and Shackelford, 2009). In addition to silicates and hydrated calcium aluminates, calcium hydroxide is another product of hydration of Portland cement that if pozzolanic materials were present in the stabilized soil, it could react with them and form additional cemented materials. Several researches have indicated that cemented materials, taken during the process of soil-cement hardening, are different from the cement hardened paste in terms of composition. In these types of compositions, strong bases form during the cement hydration, small amounts of silica and surface clay alumina are resolved and then the present calcium ions react with silica and solvent alumina and form cemented materials (Consoli et al, 2010; Fred and Maureen, 2012). Consoli et. al conducted a research on the effect of water-cement ratio on the soil-bentonite-cement composition. It showed that by decreasing the ratio of water to cement, permeability coefficient also