Evaluation of Nanomechanical Properties of Nonaggregate Phase of Asphalt Concrete Using Finite-Element Method

Abstract

Nanoindentation is a powerful tool used to study localized material behavior. However, it is not possible to directly obtain the indentation stress strain from the experimental data. In this study, an axisymmetric finite-element (FE) model was developed to study the nanoscale stress-strain distribution of the nonaggregate phase of asphalt concrete (AC) under aged and unaged conditions. To represent the field condition, the nanolevel response of the nonaggregate phase of AC was studied under fixed and increasing amplitudes of cyclic loads. The developed FE model was also used to study effects of stress variation, frictional coefficient, and bonding between the different AC lifts. From the results, it was observed that creep phenomenon at the nanolevel due to cyclic loading was much faster in the unaged condition. It was also observed that during nanoindentation, material not only undergoes a massive compressive stress, but it also generates a large tensile stress. Although the frictional coefficient was found to have no effect on the nanoindentation response, it was found that bonding between the AC lifts affects the nanolevel response of the nonaggregate phase of AC.