Poisson’s Ratio of Asphalt Concrete Mixes Using Indirect Tensile Test

Increased interest in mechanistic evaluation of flexible pavement structures has brought a demand for accurate and practical methods, models, or both to estimate the mechanical properties of asphalt concrete mixtures. One of these properties is the Poisson's ratio (nu) of asphalt concrete mixtures, which is often assumed to have a constant value of 0.35 in asphalt concrete evaluations. However, investigations have reported that mixture type, air void content, and temperature produce considerable variation in measured nu-values that could have a significant effect on evaluations of asphalt concrete mixes. The objective of this study was to evaluate the effect of air voids, binder type, and testing conditions on the measured nu-values. Indirect tensile (IDT) tests were conducted to measure nu-values. The study indicated that the Poisson's ratio of the asphalt concrete mixes, on average, attained a maximum value at a particular level of air void content. Furthermore, when comparing the Poisson's ratio values in relation to the dynamic modulus, calculated using the Mechanistic Empirical Pavement Design Guide (MEPDG) equation, higher nu-values were attained. This demonstrates the importance of measuring the Poisson's ratio of a mix type.