Organic expanded vermiculite as an alternative to filler for improving aging resistance of asphalt mixture

The organic expanded vermiculite (OEVMT) is a good anti-aging agent for asphalt binder due to its excellent heat and oxygen barrier properties. However, the application form of OEVMT is usually limited to being as a modifier for asphalt binder while seldom research takes it as an alternative to filler in asphalt mixture. Using the OEVMT as an alternative to filler has the potential to further improve the aging resistance of asphalt mixture in comparison with using the OEVMT as an asphalt binder modifier, because the amount of OEVMT in asphalt mixture can be largely increased in this case. In present study, different proportions of fillers in asphalt mixture were replaced by OEVMT to produce asphalt mixtures with better aging resistance. The effects of using OEVMT as an alternative to fillers on road performance and aging resistance of asphalt mixture were investigated. The results indicate that replacing a large proportion of fillers in asphalt mixture can lead to a poor moisture resistance of asphalt mixture. In comprehensive consideration of moisture, cracking and rutting resistances, the optimal proportion of filler that should be replaced by OEVMT is 12.5%. In comparison with the form of using OEVMT as a modifier for asphalt binder, using an appropriate amount of OEVMT to replace limestone fillers in asphalt mixture can further enhance the aging resistance of asphalt mixture by increasing the amount of OEVMT in asphalt mixture.