Characterization of effects of reclaimed asphalt pavement (RAP) source and content on dynamic modulus of hot mix asphalt concrete

<p>The effects of the reclaimed asphalt pavement (RAP) source and content on the dynamic modulus (E ^*) of hot mix asphalt concrete were characterized. Two parameters were proposed: the non-dimensional dynamic modulus-temperature index (∇E _T ^*) and non-dimensional dynamic modulus-frequency index (∇E _fr ^*). Parameter ∇E _fr ^* indicates the increase of relative E ^* per unit percent RAP from different sources during frequency and temperature sweeps, while ∇E _T ^* characterizes the reduction of relative E ^* per 1 °C temperature increase. An analysis of the results showed that ∇E _T ^* of RAP mixes were 6.80% to 12% higher than those of the control samples, indicating less temperature susceptibility. Furthermore, an analysis of ∇E _fr ^* trends showed temperature independency at higher temperature ranges. In addition, the results showed that the activation energy (AE) of the mixes was 1.51 MJ/mol/K to 9.86 MJ/mol/K higher than that of the control samples (without RAP), which depends on the RAP content and source. Moreover, E ^* linearly increases as AE increases. In conclusion, the increase of intermolecular forces owing to the higher AE in the blended binders increased the mix stiffness, which resulted in a higher E ^* in mixes containing RAP. </p>