Study On Aggregate-Asphalt Adhesion Performance Of Warm Mix Recycled Asphalt Mixture

Advancing the use of recycled asphalt pavement(RAP)is of great significance for improving resource utilization efficiency,improving environmental quality,promoting economic and social development,and comprehensive green transformation.Warm mix recycling is an asphalt pavement recycling method that conforms to the concept of green development and realizing a comprehensive green transformation in the new era.However,warm mix recycled asphalt mixture asphalt-aggregate adhesion issues have always restricted the development of recycling technology.Based on this,the article focuses on the asphalt-aggregate adhesion of warm-mix recycled mixtures.The main research results are as follows:First,the refinement of RAP and the asphalt content has been tested.The proportion of new and old asphalt in the recycled asphalt with different RAP content(20%,30%,40%,50%,60%)has been determined,and,performance analysis is performed after the rejuvenated binder has been prepared.The analysis of basic performance indicators shows that as the content of RAP increases,the consistency of recycled asphalt increases,and the tensile deformation resistance and rheological properties decrease.When the content of RAP exceeds 40%,the performance degradation rate of recycled asphalt increases.In order to improve the performance of rejuvenated binder,waste engine oil rejuvenating agent(3%,6%,9%)is added to the rejuvenated binder with a RAP content of 50% and60%,and the performance is significantly improved.Infrared spectroscopy analysis showed that the rejuvenating agent had a chemical reaction with the old asphalt,which reduced the carbonyl index(ICO)and sulfoxide index(ISO)of regenerated asphalt with high content RAP.The microscopic surface morphology of the asphalt was tested with the aid of an atomic force microscope,and it was found that the more old asphalt content,the rougher the asphalt surface,and the "bee-like" structure of the recycled asphalt surface after mixing the new and old asphalt is not obvious.Secondly,based on the theory of surface free energy,the contact angles between rejuvenated binder,limestone and three liquids have been tested,the surface free energy(SFE)has been calculated,and the parameters of wettability,work of adhesion,work of debonding and energy ratio parameters were used to evaluate the adhesion between rejuvenated binder and aggregates.The greater the amount of RAP,the lower the SFE of the recycled asphalt and the weaker the adhesion between the rejuvenated binder and the aggregate.The rejuvenating agent can alleviate the adverse effect of the amount of RAP on the adhesion.The freeze-thaw cycle test is used to explore the moisture damage resistance of different warm-mix asphalt mixtures.In actual mixing,the compatibility of new and old asphalt is poor,and it is difficult to form a uniform asphalt membrane.It is difficult for the warm mix recycled asphalt mixture to form a dense skeleton structure.As a result,the larger the amount of RAP,the faster the tensile strength ratio(TSR)the warm mix recycled asphalt mixture will decay and the greater the degree of damage after multiple freeze-thaw cycles.Finally,statistical methods are used to analyze the correlation between the factors affecting the moisture damage resistance of the warm mix recycled asphalt mixture.The results show that there is a strong linear correlation between the penetration of rejuvenated binder,the energy ratio parameters of rejuvenated binder-aggregate,and the splitting strength ratio(TSR)of warm mix recycled asphalt mixture.Among them,the linear correlation between the moisture damage resistance of the mixture with performance of rejuvenated binder is stronger.This thesis taked the effect of RAP content and regenerant on the performance of recycled asphalt,the adhesion of recycled asphalt-aggregate and the moisture damage resistance of warm-mix recycled asphalt mixture as the starting point,and explored the adhesion of warm-mix recycled mixture aggregate-asphalt at multiple scales.mechanism.Based on this research,it can be concluded that the key to improving the moisture damage resistance of the warm-mix recycled asphalt mixture and increasing the RAP content is to promote the compatible permeability of the new and old asphalt and increase the interaction between the asphalt and the aggregate.