Activation energy as a mechanistic indicator for optimising production temperatures of asphalt binders with warm mix additives

The use of modified binders in asphalt construction is rapidly increasing because of their advantages, such as enhanced durability, reduced energy consumption and improved pavement performance. Among these, warm mix asphalt (WMA) additive modification has gained significant attention because of its ability to lower production temperatures, thereby reducing fuel usage and greenhouse gas emissions. However, evaluating the actual mixing temperature (MT) reduction remains challenging, particularly for highly modified binders and for additives that do not exhibit significant viscosity reduction after modification. To address this limitation, the present study explores the concept of the activation energy (E a), derived from the Arrhenius model, to evaluate the thermal sensitivity and temperature-dependent flow behaviour of asphalt binders within the temperature range of 150 °C–180 °C. Three different binder grades (VG30, PMB40 and CRMB60) and three different WMA additive types with varying dosages were considered. The results indicated that both the type and dosage of WMA additive had a significant influence on the variation in E a values. An overall increase of nearly 25% in E a was observed when the base binder changed from VG30 to CRMB60, reflecting the greater thermal resistance of the modified binders. Furthermore, MT reductions ranging from 23 °C to 34 °C were observed depending on the additive type and dosage, confirming the ability of the E a-based approach to predict temperature reduction effectively. Lastly, the functional relationship between additive dosage and E a was explored to understand the behaviour of different additive–binder combinations.