Research Of High Temperature And Fatigue PRO Perties Of Asphalt And Asphalt Mixture Under Light And Heat

Strong ultraviolet radiation and high temperature are the climate characteristics of Guangxi in summer.Asphalt materials are easy to age in light and heat environment,thus the road performance and durability of asphalt are seriously affected.Based on the actual environmental conditions in Guangxi,this paper determines the indoor light and heat action test parameters,carries out high temperature performance test and fatigue performance test analysis on asphalt and asphalt mixture with different aging degrees,and provides certain reference application value for the service life evaluation of asphalt concrete pavement and the guidance of maintenance engineering under the climatic conditions in Guangxi region.The research on asphalt performance shows that the high temperature performance of asphalt is enhanced by photothermal effect.With the prolongation of photo-thermal action time,the cumulative strain of asphalt gradually decreases,and the viscous portion G_v of asphalt stiffness modulus gradually increases.Logarithms of cumulative strain and G_v value show good linear relationship with temperature under test conditions.Under light and heat conditions,the creep recovery rate of asphalt gradually increases,the unrecoverable creep compliance gradually decreases,and the stress sensitivity indexes R_diff and J_nr.diff gradually decrease,indicating that the elastic recovery performance of asphalt is improved,the permanent deformation resistance increases,and the stress sensitivity decreases.Under the influence of light and heat,the energy consumed in the process of asphalt shear deformation increases and its ability to resist shear load gradually decreases.The photothermal effect weakens the self-healing ability of asphalt,and the healing degree of asphalt performance increases with the extension of intermittent time.In the same interval time,the recovery degree of complex shear modulus of matrix asphalt and linear SBS modified asphalt is greater than fatigue life.After an interval of 12 hours,the modulus,fatigue life and modulus change rate of the two asphalts are basically restored to the initial state,and it is considered that there is no need to extend the interval time.For asphalt mixture,the rutting depth and creep slope gradually decrease with the deepening of photothermal effect,indicating that its high temperature stability is improved,but its fatigue life under different strain levels gradually shortens,indicating that its durability deteriorates.Under different aging degrees,the high temperature and fatigue properties of asphalt binder are positively correlated with asphalt mixture.Based on the grey correlation analysis theory,it is found that the cumulative strain and unrecoverable creep compliance index are highly correlated with rutting depth and creep slope.It is believed that the cumulative strain and unrecoverable creep compliance index of asphalt can better reflect the high temperature performance of the mixture,while the fatigue performance aspect,the fatigue life healing index HI² value of asphalt intermittence of 0.5h is more consistent with the change trend of the fatigue life of the mixture.