Environmental and mechanical performance of crumb rubber modified warm mix asphalt using Evotherm

- Performance of CR-WMA from collected from laboratory and field were evaluated.
- The performance of CR-WMA, CR-HMA and conventional HMA were compared.
- CR-WMA showed fuel saving and hazard emission reduction.
- Fatigue, moisture damage, rutting and thermal cracking resistance performances were evaluated.

While crumb rubber (CR) can improve the performance of asphalt pavement in several aspects, it has a noticeable concern of higher emission and increased energy consumption due to a higher production temperature. This study made a comprehensive evaluation of the environmental and mechanical performance of the CR modified warm mix asphalt with Evotherm third generation. The CR modified hot mix asphalt (HMA) and control HMA were also investigated for a comparative study. Moreover, both the laboratory compacted samples and the field collected samples were studied. The environmental performance includes the neat asphalt savings, fuel savings and hazard emission reduction. The mechanical performance evaluated included tensile strength and moisture susceptibility, rutting resistance, anti-stripping performance, fatigue performance, and low temperature performance. The neat asphalt saving with CR was found to be 5.8% compared to unmodified asphalt. The fuel savings in this study was around 13%, and a visible hazard emission reduction was observed as well. The mechanical performance results showed that the CR-WMA with Evotherm had equivalent rutting resistance and low temperature performance and better fatigue performance and moisture damage resistance compared to the CR-HMA. The CR-WMA with Evotherm and CR-HMA had a higher tensile strength and better low temperature performance than the control HMA. In regard to the comparison between the CR-WMA and CR-HMA, the laboratory compacted and field collected samples were consistent overall. The results also indicated that the moisture damage resistance evaluated through the tensile strength ratio and the HWT may not perfectly agree with each other.