Mixture of Lime and Rice Husk Ash influence on Saturated Hydraulic Conductivity of a sandy loam soil

One of the most widely used geotechnical parameters is hydraulic permeability, which is affected by pore distribution and surface area of soil particles and any parameters cause a major change in hydraulic permeability. In the present study the effect of adding hydrated lime and mixture of rice husk ash and hydrated lime at the ratio of 1:1 on horizontal saturated hydraulic conductivity was examined by using of sample physical model. Mixtures of lime and rice husk namely: 2, 4 and 6 % by weight of dry soil) were added to a non-cohesive sample, and hydraulic permeability was tested after 28 days. The results showed that addition of lime to the soil increased its hydraulic conductivity. Addition of 4 % mixtuer yielded the maximum hydraulic conductivity. Addition of more lime decreased the hydraulic conductivity, although greater than hydraulic conductivity of control sample. Results showed that rice husk ash and lime mixture acts as a catalyst and accelerates the pozzolanic reaction, which in turn causes a partial decrease in the hydraulic conductivity of sample. These results are attributed to effects of two processes of cation exchange and pozzolanic reaction between lime and rice husk ash on the hydraulic conductivity.