Numerical analysis of field aging in asphalt pavements via coupling of diffusion process and kinetics aging model

The asphalt aging model is a crucial module in the Mechanistic-Empirical (ME) pavement design programme for asphalt pavement performance prediction. In this study, an analytical aging model that couples diffusion and kinetics aging model (CDKAM) is improved to analyze and predict the field aging of asphalt pavements. The complex modulus (E*) of field cores was used as the aging property to illustrate the derivation of explicit expressions of time-averaged thermal source term ( $ \overline {TST} (t ) $ TST over bar (t)) and time-averaged diffusion coefficient ( $ \bar{D}(t ) $ D over bar (t)). The value of the material-related parameter (M) in $ \overline {TST} (t ) $ TST over bar (t) model differs among different mixtures, which could assess the mixture's susceptibility to thermal oxidation. The CDKAM with $ \overline {TST} (t ) $ TST over bar (t) and $ \bar{D}(t ) $ D over bar (t) was used to predict E* of field aging for asphalt pavements in Texas after 22-month service life. The calibrated CDKAM could reasonably quantify the aging extent over time and the aging gradient over depth for studied asphalt pavements.