Effect of Chemical and Palm Oil-Based WMA Additives on Binder and Mixture Performance

Performance stands out as the most important factor when designing asphalt materials. Warm mix asphalt (WMA) mixtures are viable options for sustainable solutions since they are generally considered environmentally friendly due to significantly lower mixing and compaction temperature requirements, resulting in lower greenhouse emissions and fuel consumption. Furthermore, WMAs are very compatible with recycling processes and tend to allow greater use of recycled asphalt pavements (RAP). In addition, no negative effects have been observed regarding physical and rheological properties and the performance can be improved with the use of polymers. In the current paper, the performance of WMAs with four different chemical additives and a natural additive based on palm oil were analyzed. The effects of the additives on the binder performance were based on several rheological parameters: performance grade, multiple stress creep recovery (MSCR) and linear amplitude sweep (LAS). For the asphalt mixture, performance was analyzed through permanent deformation measured by means of the Hamburg wheel tracking test. The results of this study indicated that the use of warm mix additives improved the performance of the asphalt binder in a wide spectrum of temperatures: at low and intermediate temperatures, the resistance to cracking was enhanced, and at high temperatures, rutting resistance was also improved. At the mixture level, the volumetric properties and performance were also improved.