Viscoelastic and Poisson's ratio characterization of asphalt materials: critical review and numerical simulations

The vast quantity of asphalt concrete being used in the U.S. highway system demands deeper understanding of the material to ensure sustainability of the highway pavement system. Poisson's ratio, though a vital material property for elastic materials, does not serve the purpose of material characterization for viscoelastic materials like asphalt concrete. This paper presents a brief review of existing literature on the use of Poisson's ratios in general and by the asphalt research community in specific. The literature review revealed that the majority of existing studies assumed a constant Poisson's ratio of 0.3-0.35. Few analytical simulations have been conducted to realize the time and stress dependence of viscoelastic Poisson's ratios. The errors caused by incorrectly assuming constant Poisson's ratios and the same moduli relaxation times for viscoelastic materials were quantified. The effect of varying moduli ratios on Poisson's ratios was also studied. This study concludes that assuming a constant Poisson's ratios and similar relaxation times can lead to serious errors in characterization of asphalt mixtures.