PFWD, CBR and DCP evaluation of lateritic subgrades of Dakshina Kannada, India

Abstract

The performance of pavements depends to a large extent on the strength and stiffness of the subgrades. Among the various methods of evaluating the subgrade strength, the use of portable falling weight deflectometers (PFWD) is gaining popularity in the recent years. This is due to its simplicity in design, portability, and the added advantages of providing quick and reliable estimates of the Young's modulus of elasticity of pavement subgrades. Hence it was felt that there is a need to study the correlation between results obtained using the PFWD and those obtained using the traditional approaches such as the California bearing ratio (CBR) test, the dynamic cone penetrometer (DCP) test. The work described herein focuses on exploring the correlations between the results obtained using the PFWD, and the results obtained using the CBR method and DCP for lateritic soils at various locations of Dakshina Kannada district of the State of Karnataka, India. Regression models were developed as part of this study to enable the prediction of CBR values based on the average of observed values of the Young's modulus obtained using the PFWD (Epfwd), and prediction of Epfwd from the average penetration-rates of DCPs performed for field density, and field-moisture content.