Assessment of warm asphalt mix additives for High-Modulus Asphalt production

Abstract: The production and paving of asphalt mixes used in constructing flexible asphalt pavements are contribute to Greenhouse Gas (GHG) emissions, presenting an opportunity for implementing environmentally friendly practices, which may also be economically beneficial. The existing South African guidelines for designing Enrobé à Module Élevé (EME), or High Modulus Asphalt (HiMA), recommend using hard penetration-grade bitumen (10/20 or 15/20 pen), which require high mixing and compaction temperatures (up to 170°C and 150°C, respectively). Implementing warm mix asphalt technology in EME can potentially reduce energy consumption, and mitigate environmental harm. Using warm mix additives in EME production has the additional effect of minimizing ageing of the binder during mixing and compaction. A key consideration when incorporating warm mix asphalt technology into EME is ensuring compliance with short and long-term performance requirements. This study investigated the properties of EME bitumen blended with various proportions of locally available warm mix asphalt additives, focusing on rheological modifiers (viscosity-reducing additives). The most promising additive was subsequently used to produce asphalt specimens for evaluating workability and compactability. The findings of the study provide valuable insights into the use of warm mix asphalt technology in EME and recommend an appropriate approach to incorporating this technology. It is expected that the successful implementation of warm mix asphalt in EME will lead to improved cost-effectiveness and greater environmental health, without sacrificing the performance of the EME.