Performance characterization of asphalt mixtures under different aging levels: A fracture-based method

Abstract

This paper proposes a straightforward approach to characterize the fracture properties and fatigue life of asphalt mixtures over the service time. Since the serviceability of flexible pavements varies as they age, assessing the performance of asphalt mixes under aged conditions is essential. To investigate the sensitivity of fracture-related parameters to aging, accelerated laboratory aging, which is conditioning asphalt concrete samples in a force draft oven for different aging times (0, 3, 5, 7, and 9 days), was used. The Semi-Circular Bending (SCB) test at 25 °C was carried out on neat and activated carbon-modified samples to examine the fracture responses of asphalt mixes. First, force–displacement curves at failure were plotted. Then, fracture-related parameters (e.g., peak load, fracture toughness, strain energy, and J-integral) and damage levels corresponding to each fracture criteria were measured versus aging levels. In addition, the fatigue life ratio was determined to measure the influence of aging on the long-term performance of asphalt mixtures. To incorporate the effect of aging on the overall cracking resistance of asphalt mixtures, different fracture-related parameters versus service time were studied. Experimental findings suggest that the area under the fracture property versus service time can provide a reliable index for evaluating the long-term performance of asphalt mixtures. In addition, statistical analysis was performed to assess the impact of aging on fracture-related parameters obtained from the SCB fracture test. The proposed method was able to simultaneously factor in the fracture resistance and the rate of damage development during flexible pavement service life.