Evaluation of field aging effect on self-healing capability of asphalt mixtures

Abstract

Asphalt mixtures have the potential to repair a part of their cracks through self-healing capability. However, various factors, such as aging, can influence the effectiveness of this phenomenon. In this respect, it is very important to consider the real effects of field aging. Therefore, this study investigated the effects of long-term field aging on the self-healing capability of asphalt mixtures. For this purpose, three asphalt pavement sections with similar mix designs and service life of 7, 10, and 11 years were studied through Fourier transform infrared spectroscopy (FT-IR). Then, the middle part of the asphalt layers was core-drilled, and their self-healing capability was evaluated using Semi-Circular Bending (SCB) test. The samples were healed using heating in a forced draft oven at three temperatures of 35, 60, and 85℃ for 8, 16, and 24 h. Also, the three-point beam bending test was used to examine the effects of aging on the self-healing capability in the thickness of the asphalt layer. The results showed that the self-healing ability of asphalt can be influenced by the aging changes in its layer thickness. The asphalt samples with a service life of 11 years exhibited a difference of about 10 % between the surface’s self-healing index and the layer’s depth index. In addition, it was seen that the self-healing index of the middle part of the asphalt layers in the period of 7 to 11 years was almost constant and equal to 35 %. Based on the obtained results, it can be concluded that the changes in the Carbonyl Functional Group Concentration (CFGC) were directly associated with the changes in the self-healing ability of asphalt pavements in its thickness due to aging. Therefore, CFGC can be used as an indicator to estimate the self-healing capability of asphalt mixture in the depth of pavement layers.