Evaluating in-service asphalt concrete damage using surface waves

Abstract

Two in-service asphalt concrete highway sections exhibiting surface distresses indicative of moisture damage were evaluated using multichannel analysis of surface waves. The computed viscoelastic moduli were shifted to a typical 25 Hz design value using a dynamic modulus-based master curve using drilled core specimens. Models of the built-up asphalt concrete layers were constructed using frequency-shifted shear wave velocity dispersion curves. Dynamic modulus and indirect tensile strength values from drilled core specimens did not correlate well with observed surface distresses or internal damage levels. However, the modelled frequency-shifted moduli derived from surface wave testing appeared to correlate well with variations in material layering, modulus and damage observed over the depth of the asphalt concrete. Evaluating the built-up asphalt concrete layer in pavement structures enables a more rigorous evaluation of the internal stresses and strains for failure and service life prediction than can be achieved using an average modulus approach.