Effect of Distresses on Deflection Basins and Backcalculation Modulus of Asphalt Pavement with Cement-Treated Base

Abstract

The Falling Weight Deflectometer (FWD) is widely used to evaluate the asphalt pavement structural conditions through the deflection basin and the backcalculation modulus. The FWD test has sometimes been performed on asphalt pavement with distresses. It is necessary to investigate the effect of the distresses on the deflection basin and the backcalculation modulus. In this study, the finite element method (FEM) was used to simulate the asphalt pavement with and without the distresses and the FWD load, and thus produce the defection data. The modulus of the structural layers and subgrade was backcalculated from the FWD data using the MODULUS 6.0 program. Then the effect of the distresses was investigated on the deflection basin and the backcalculation modulus. The results indicate that the cracking and cement-treated base crushing in the asphalt pavement may result in an abnormal deflection basin and make the backcalculated modulus incorrect; therefore, it may be necessary to remove the unusual deflection basin before the backcalculation to obtain accepted backcalculation results, or decrease the number of structural layers to reduce the unreasonable backcalculation results.