Research On The Adhesive Properties Between Asphalt And Aggregate Based On The Theory Of Surface Free Energy

With the continuous development of the transportation industry,the moisture damage of asphalt pavement is more and more serious and the problem is concerned.The adhesive and wetting properties of asphalt and aggregate is an important factor on the resistance to moisture damage of asphalt pavement.Based on the theory of surface free energy,this paper has done some research to evaluate the adhesion of asphalt and aggregate under normal temperature and high temperature.On the basis of this evaluation method,this paper has also investigated both the influence of asphalt modifier and the effect of asphalt aging on the surface free energy of asphalt and the adhesion properties between asphalt and aggregate.The results show that:At the normal temperature,The proportion of the dispersion component of the asphalt surface free energy is much larger than the polar component,The adhesion work of asphalt and Penglai basalt is greater than that of asphalt and Nanchen granite in dry and wet environment.The moisture resistance of asphalt and Penglai basalt is much greater than that of asphalt and Nanchen granite.The ability to resist moisture damage increases with the asphalt softening point and the viscosity increasing.The resistance to moisture damage is consistent with the change trend of retained Marshall stability;The influence of thin film oven aging process on the adhesion properties of asphalt and aggregate is not obvious.After aging of mixing,the surface energy of the asphalt is reduced at room temperature,the dispersion component is reduced,the polarity component is increased,and the moisture resistance of the asphalt and aggregate is reduced;For the effect of adding asphalt modifier,the surface free energy of neat asphalt increases after being modified by rubber powder and SBS in turn.The dispersion component is increased and the polarity component is reduced after the neat asphalt is modified by rubber powder.The dispersion component decreases and the polarity component increases after being modified by SBS.The resistance to moisture damage of asphalt increases by being modified by rubber powder which reduces because of being modified by SBS.Under the high temperature,the surface tension of the asphalt decreases linearly with increasing temperature.The relationship between adhesion work and temperature is in accordance with quadratic equation.The maximum adhesion work can be obtained at the corresponding temperature.The maximum adhesion work between the different aggregates and the asphalt is substantially equal and the corresponding temperature is reached also approximately the same.The factor that affect the maximum adhesion and the corresponding temperature of the asphalt and aggregate is mainly the viscosity of the asphalt which is almost not related to the properties of the aggregate.For neat asphalt,the temperature corresponding to maximum adhesion work is similar to the mixing temperature determined by the relationship between viscosity and temperature.While the modified asphalt is quite different;The absolute value of the asphalt diffusion coefficient rises linearly with the increasing of the temperature,and the logarithm of the initial contact angle decreases with the increasing of the temperature;At high temperature the surface tension of the asphalt is reduced after mixing aging,and the maximum adhesion work and the corresponding temperature are reduced.