Modulus based Approach of Lateritic Subgrade Soil Strength Evaluation Using Light Weight Deflectometer

Abstract

Since density based approach of pavement evaluation have its own limitations, quality control procedures of compacted pavement layers across the globe is slowly shifting from density based to stiffness/strength based criteria. The stiffness based measurements are easy to measure and more reliable than the density based quality measurements. The light weight deflectometer (LWD), one of many cutting-edge methods for determining how stiff compacted layers are, is employed in this study as a quality control tool to evaluate the standard of compacted pavement layers. LWD was created to assess the soil's compacted surface stiffness. LWD gives in situ measurements of soil densification through deformation/deflection modulus. In this study influence of moisture variations on the strength of subgrade layer are studied with the help of LWD. For this purpose an earthen shoulder along the road section inside the RIT College campus was excavated to the subgrade depth. At the subgrade level, soil samples nearly of 15 grams were collected for finding out the moisture content at that particular instant. LWD test was done from which the resilient modulus of the surface under test can be estimated. LWD resilient modulus is influenced by several soil parameters such as grain size distribution, maximum dry density (MDD) and optimum moisture content (OMC).Variation of LWD modulus with dry density studied at different test locations. A regression model was developed between LWD modulus and the factors influencing LWD modulus such as fineness modulus and moisture content for various combinations of lateritic and silty soil blend.