Aging behavior and long-term performance: a comparative study of hot mix versus chemical warm mix asphalt

Warm mix asphalt (WMA) is recognized for its eco-friendly attributes minimizing energy consumption and emissions during production and application of asphalt concrete (AC). Yet, a comprehensive assessment of the performance of each WMA technology in the long term is pivotal to validate its role in advancing sustainability and infrastructure resilience. Most of the previous studies investigated the effect of aging on hot mix asphalt (HMA) and WMA mixtures by assessing the properties of extracted original and WMA binders. Hence, there is a necessity for mechanistic evaluation and practical comparison of the performance of aged AC using each WMA technology against HMA at the mixture level through linear viscoelastic characterization, while taking into account local materials. This is conducted in this study by measuring the dynamic modulus and phase angle of short- and long-term aged HMA and chemical WMA samples across a spectrum of temperatures and loading frequencies. Additionally, the flow number (FN) and the simple performance indicators were computed to further evaluate the mixtures’ susceptibility to rutting and fatigue distresses. The results suggested that the use of chemical additive in WMA improved the mixture’s resistance to aging. Additionally, the findings of the statistical analysis revealed a significant increase in the dynamic modulus of both chemical WMA and HMA mixtures over the long term. Notably, chemical WMA exhibited generally smaller dynamic modulus and higher phase angle values than HMA under various temperature and frequency conditions during both aging scenarios. This implies that chemical WMA exhibits decreased rutting resistance, remaining within acceptable levels with FN values above 190 cycles, while enhancing fatigue resistance and subsequently improving durability in both short and long-term scenarios.