Research On Performance Prediction Model Of Recycled Asphalt Based On Surface Energy Theory

The asphalt acts as a binder in the asphalt mixture.The performance changes of the asphalt will be most directly reflected in the performance of the mixture,further affecting the pavement performance and service life of asphalt pavement,therefore,the evaluation of asphalt pavement performance is essential.At present,the evaluation of asphalt performance is often measured by standard test to obtain the macroscopic values.The actual test process is empirical with a large demand for asphalt,and there is no systematic analysis of the inherent factors of asphalt performance.While the surface free energy is an important internal factor that causes the change of asphalt performance.From the point of view of free energy,establish the relationship between microstructure and macroscopic performance can make the analysis & prediction of the macroscopic performance of asphalt more accurate and make better performance improving.Therefore,the researches of this paper are mainly from the following aspects:First,in this paper,the contact angle of the titrated liquid on the surface of the base asphalt is measured by the method of sessile drop.The surface free energy and its component of the test asphalt are calculated according to the Owens-Wendt theory.The aged asphalt was prepared by simulating road aging with RTFOT and PAV respectively.Second,the trend of influence of the amount of the free energy on the asphalt performance was studied by analyzing properties of the surface free energy of the basic asphalt and the penetration,10? ductility,softening point,Brookfield viscosity and the other performance index involved in SHRP plan.Analyze of the relationship between the surface free energy and the content of the four components of the basic asphalt,and then study the influence of the content of the components on the surface free energy.The results show that the correlation coefficient between the surface free energy and the Brookfield viscosity is 0.9095,and the correlation coefficient between the dispersion component and the rutting factor is above 0.9517,which indicates that the free energy and the two properties have a good linear relationship.The result of the analyze of the relationship between the basic asphalt and the content of the four components shows that the correlation of the asphaltene,aromatic fraction,glial and surface free energy is insignificant.The relationship between aromatic fraction and glial was positively correlated with surface free energy,and the relationship between natural logarithm of the asphaltene and surface free energy was negatively correlated.Saturated fraction is linearly negatively correlated with surface free energy,with a correlation coefficient of 0.8792.Finally,the influence of recycling agent on the surface free energy of asphalt was studied.The surface free energy and aging time of aged asphalt were analyzed and the influence of the aging of asphalt on the surface properties of asphalt was systematically studied.The performance of recycled asphalt was rapidly evaluated by the surface free energy of recycled asphalt.The results show that the increase of the recycling agent content reduces the surface free energy of the aged asphalt,and the surface free energy of the recycled asphalt still has a good linear relationship with the rutting factor.