Quality Assessment of Road Shoulders using Light Weight Deflectometer and Geogauge

Abstract

Shoulders are an important element of the highways that provide space for vehicles to stop during an emergency. A well-compacted shoulder provides structural firmness to a pavement by transferring overlying traffic loads to the underlying soil stratum. They provide lateral support to the pavement. In recent years, the use of non-destructive testing devices like Geogauge and Light Weight Deflectometer (LWD) has emerged in our country. The main reason behind this is the inbuilt ability of Geogauge and LWD in the fast estimation of the elastic modulus of a shoulder on top of their ease to port, being cost-effective, the capability to give more amounts of data, etc. Thus, there is a need to assess these devices. The main objective of this paper is to develop correlations between the parameter obtained from these non-destructive devices and destructive test parameterslike dry density and CBR. The tests were conducted on thirty-two locations of road shoulders at the city of Patna, India. Geogauge, LWD and sand replacement or sand cone testing were performed at different locations and soil samples were collected for determination of CBR and water content in the laboratory. The result of regression analysis shows that a significant correlation exists between moduli obtained from the devices under investigation and standard test results i.e. dry density and CBR. These developed correlations may be used by the road engineers for assessment of the quality of the shoulders.