Modeling Asphalt Oxidation in Pavement With Field Validation

A model for asphalt oxidation in pavement was developed based on fundamentals of oxygen diffusion in the mastic and reaction with asphalt. Diffusion depth, a concept different from the conventional film thickness, defined the oxygen diffusion region in the mastic. A field calibration factor accounted for the factors not considered in the model such as the effect of small aggregate particles on oxygen diffusion. Carbonyl area and viscosity of binders recovered from field cores were measured and were used for model calibration and validation. Results demonstrated that the proposed model estimates carbonyl growth over time in pavement, layer by layer, quite well.