Modelling of the performance of asphalt pavement using response surface methodology—the kinetics of the aging

Asphalt (A1) of the Marshall specimens tested in the third step of response surface methodology (RSM) and asphalt (A2) of the cores with real aging was recovered according to ASTM D 5404 [Annual Book of ASTM Standards. Section Four. Construction. vol. 04.03. Roads and paving material; vehicle–pavement systems. ASTM. 2000]. Adherence and hardness of the asphalts (A1 and A2) were tested by a texture analyser, and also penetration test was evaluated according to ASTM D 5 [Annual Book of ASTM Standards. Section Four. Construction. vol. 04.03. Roads and paving material; vehicle–pavement systems. ASTM. 2000]. The crystallised fractions (CF) and the carbonyl groups (CO) contents of the asphalts (A1 and A2) was determined by differential scanning calorimeter (DSC) and Fourier Transform Infrared (FTIR), respectively. The change in the content of CF and CO for A1 was described by a first-order Arrhenius equation, with a small activation energies that suggested a diffused–controlled process of the crystallites and the oxidation of the asphalt, which is related with the decrement in adherence and the increment in hardness and in penetration, highly dependent of aging time.