Laboratory evaluation of warm mix asphalt incorporating high RAP proportion by using evotherm and sylvaroad additives

• Two different types of additives were used to produce WMA mixtures incorporating high RAP content.
• The effect of WMA additives on the binder’s viscosity.
• Laboratory performance evaluation on moisture susceptibility, fatigue cracking and rutting resistance.

Warm mix asphalt (WMA) has gradually become more popular in the roading industry as compared to HMA, WMA can bring numerous benefits, such as lower energy consumption, lower emissions, and higher ability of incorporating a high proportion of reclaimed asphalt pavement (RAP) in WMA mixtures. Incorporating RAP in WMA can increase the sustainability benefits and enhance the performance of WMA. This study investigated the performance of WMA adding RAP with different proportions, from 0 to 70% by mass of WMA. The performance of mixtures was compared with a control HMA. One type of binder, 80/100 penetration grade, and two types of additives were used, including a chemical warm mix additive and a rejuvenator. Tests were done on the binder’s viscosity and mechanical performance of mixtures such as moisture resistance, fatigue cracking and rutting resistance. The results showed that the two additives reduced the viscosity of the binder. Mixtures with the chemical additive performed better than other mixtures in terms of moisture resistance. Only WMA mixture with the rejuvenator showed a higher number of cycles to fatigue failure than the control HMA. For rutting resistance, the increase in RAP proportion greatly improved the performance of WMA mixtures. WMA without RAP had a lower number of cycles to reach maximum rut depth than the HMA. All WMA-RAP mixtures showed considerably better rutting resistance than the HMA.