Influence of sand on strength characteristics of cohesive Soil for using as Subgrade of road

For safe and cost effective construction of pavement, subgrade plays an important role and such layer is constructed generally with suitable fill materials collected and transported from the borrow pits nearby to the proposed construction site, resulting in creation of low lying areas as well as loss of top productive layer of soil. Usually cohesive soil is one type of the weak soil which is a typical example of available soils in flood-plain of West Bengal, which is an extension of Indo-Gangetic plane, used for construction of subgrade of road. Further sand is a naturally occurring granular material composed of finely divided rock and mineral particles and generally it is used as a filler material because of its high load bearing capacity particularly in confined condition. So for improving the different properties of cohesive soil, an exhaustive study has been undertaken by the author to test possible uses of various types of sand with varying proportions ranging from 5% to 15% as admixture to cohesive soil and to evaluate their different properties e.g. plastic properties, compaction properties and strength properties in terms CBR of the mixtures. Experimental results indicated the better improvement in the compaction characteristics as well as in the CBR for addition of fine sand upto 15% with the soil and identified as cost effective mix proportion for the construction of subgrade of flexible pavement. (C) 2013 The Authors. Published by Elsevier Ltd.