Noise abatement in asphalt concrete pavements: Part 1. Non-destructive estimation of characteristic lengths using an impulse-echo approach

Treating asphalt concrete mixtures as porous viscoelastic media, an impulse-echo (I-E) non-destructive evaluation approach is presented to estimate the viscous and thermal characteristic lengths of several asphalt concrete mixtures within the rigid-frame and high-frequency limits of Biot's poroelastic theory. Simulating a tyre-tread impulse on the pavement surface, this approach allows the independent evaluation of these characteristic lengths for each asphalt concrete mixture at ultrasonic frequencies from a single impulse-echo test. These characteristic lengths describe the fluid-solid frame interactions and are related to the noise abatement characteristics of pavements made of asphalt concrete mixtures. Other estimated material parameters include the quality factor, Q, the formation factor, F, tortuosity, τ², characteristic frequency, f_c, airflow resistivity, σ, and permeability, κ₀.