Study On The Aging Performance And Anti-aging Methods Of Reclaimed Asphalt

In the process of asphalt pavement renovation,the recycle of waste asphalt mixture can not only greatly save asphalt and petroleum resources,but also protect the ecological environment,which is in accord with the basic state policy on our country transportation sustainable development.Previous researches showed that the pavement performance of regenerating asphalt mixture could be enhanced effectively by the compounding of new asphalt,aged asphalt and a certain dosage of regenerant.Similar to the common asphalt mixture,both thermal-oxidative and photo-oxidative aging will also occur in the actual use process of regenerating asphalt mixture.Therefore,the system evaluation of regenerating asphalt aging performance and investigation of the method to enhance its thermal-oxidative and photo-oxidative aging resistance is significant to extend the service life of regenerating asphalt pavement.In this paper,aged asphalt,new asphalt and regenerants were mixed by melt blending method to obtain regenerating asphalt.The influence of regenerant dosage,regeneration technology and the types of regenerant on the physical and rheological properties of regenerating asphalt was investigated by the physical and rheological measures,and the optimum dosage of regenerant was determined.In addition,various laboratory aging methods such as thin film oven test(TFOT),pressure aging vessel(PAV)and ultraviolet radiation(UV)were utilized to simulate the aging of regenerating asphalt,and the aging performances of the new asphalt and regenerating asphalt were compared.Finally,the compound modifier consisting of nano-zinc oxide(nano-ZnO)and organic expanded vermiculite(OEVMT)was introduced to prepare the compound modified regenerating asphalt.The influence of different contents compound modifier on the physical and rheological properties of regenerating asphalt after different aging methods was studied,and the optimum content was determined in the end.The main conclusions are as follows:(1)The influence of two different regeneration technologies on the properties of regenerating asphalt is very small.Based on the experiment on the influence of different dosages regenerant,the physical performance of regenerating asphalt containing 10%dosages regenerant is the closest to that of new asphalt,namely 10%is the optimum dosage.However,the further investigation indicates that the optimum dosage cannot be good to make the rheological properties of regenerating asphalt restored,especially at medium temperature area rheological properties.(2)Compared with new asphalt,the ability of regenerating asphalt to resist short-term and long-term thermal-oxidative aging is better,while the ability to resist UV aging resistance is worse.(3)The addition of compound modifier can enhance the high temperature stability of regenerating asphalt,whereas reduce the plastic deformation capacity to some extent.(4)The compound modifier can enhance both the thermal-oxidative and photo-oxidative aging resistance of regenerating asphalt effectively.But,for the short-term thermal-oxidative and photo-oxidative aging,compound modifier has the opposite effect when the content exceeds a certain value.(5)Overall considering the physical and rheological test results of the compound modified regenerating asphalt after different aging methods,it can be determined that the optimum content is 1%OEVMT+3%nano-ZnO.