Research On The Effect Of Temperature On The Cracking Resistance Of Asphalt Mixture

Two kinds of damage modes of asphalt mixture,fatigue cracking and permanent deformation,are continuously accumulated under the combined action of vehicle load and various environmental factors.It is necessary to study the law of its development and how to evaluate and predict the cracking resistance performance of the mixture.At the same time,the development degree of fatigue cracking is closely related to the temperature while these two types of damage occur simultaneously at different temperatures.Therefore,in order to accurately evaluate the cracking resistance of mixture,it is necessary to study and quantify fatigue cracking and permanent deformation at each temperature,and analyze the effect of temperature on the cracking resistance.On the basis of the objective conditions of asphalt pavement service,test scheme of fatigue damage was designed,4 kinds of asphalt mixture were tested with direct repeat tensile test of different strain levels at different temperatures,to obtain the nondestructive stage and destructive stage mechanical properties,determine the fatigue cracking pattern under the effect of temperature and temperature-related cracking resistance performance evaluation index.Firstly,the Dissipated Pseudo-Strain Energy(DPSE)is derived from the Pseudo-Strain which eliminate the energy of linear viscoelastic effect.Based on the data analysis of 20℃ fatigue test,DPSE contain the nonlinear viscoelastic effect,and fatigue cracking and permanent deformation damage effect.Then the connection among DPSE,damage density and stress amplitude was established based on the energy balance equation,so that the parameters of modified Paris’ Law was easily calculated,and theoretically deduce and verify parameters nJR was linearly related to logarithmic form of parameters AJR.According to the damage density,the smaller the parameter nJR is,the stronger the anti cracking ability of the material is.The single temperature fatigue damage test extended to other temperature(including 0℃,10℃,20℃,30℃and 40℃),each DPSE component are isolated from each other.With the temperature increasing,it exhibited that distribution energy to overcome fatigue cracking(DPSEF)energy ratio increases first and then decreases while distribution energy to overcome permanent deformation(DPSEP)energy ratio decreased continuously.If only for the energy analysis of damage effect,it was found that the dominant damage mode is fatigue cracking in the 0℃ to 20℃ interval.The dominant damage mode at 40℃is permanent deformation,and the dominant damage mode at 30℃ depends on material types.Finally,the parameters of the modified Paris’ Law are obtained more accurately by DPSEF which reflect the cracking resistance properties of different temperatures,and the relationship between the two parameters does not change with temperature.The results show that when subjected to the same level of strain,the development of fatigue crack first aggravates and then moderates,and the cracking is most severe at 10℃.The crack resistance of SBS modified asphalt mixture at each temperature is better than that of 70#matrix asphalt mixture,and the cracking resistance varies with temperature depending on the material.The research results can provide fatigue performance evaluation methods for asphalt mixtures considering the influence of temperature factors on the cracking resistance of materials,so as to provide theoretical guarantee for accurately predicting the life and performance of asphalt pavement and economic analysis.