Optimum Moisture Content, and Permeability of Sandy Soils

In this paper a concept of mean particle size and size factor is presented and an attempt is made to relate the coefficient of permeability with mean particle size, keeping in view the optimum moisture content and maximum dry density. The particle size distribution has a marked impact on the coefficient of permeability. The mean particle size and the size factor can be found out from the gradation curve. For the purpose of experimental analysis, ten samples of sandy soils were prepared in the laboratory by taking different proportions sand and siltclay mixtures. The clean sand and clean clayey silt were blended with different percentages of sand, silt and clay to form ten samples of sandy soils. For actual determination of coefficient of permeability a triaxial testing machine having two constant pressure systems was used and the samples were compacted at standard Proctor density. A log-log plot between mean particle diameter and the coefficient of permeability indicated a straight line relationship that holds good for all the sandy soil samples tested. Therefore, a permeability guide is evolved which relates mean particle size with coefficient of permeability.