| As one of the main damage form of asphalt pavement,fatigue cracking has always been a hot issue in the field of road engineering.Fatigue cracks in Asphalt mixture are usually generated inside the asphalt mastic and the interface between asphalt and aggregate.It means that the adhesion performance between asphalt mastic and aggregate will be an important factor affecting the overall fatigue performance of asphalt mixture.However,there are still some difficulties in directional investigation of the effect of interfacial bonding characteristics on fatigue.On the one hand,there are many difficulties in preparing and testing the asphalt-aggregate interface phase.On the other hand,the fatigue performance of the mixture is affected by aggregate gradation,specimen forming,etc.,many factors need to be controlled.Therefore,it is very necessary to study suitable test methods to analyze the influence of the adhesive properties of asphalt mastic-aggregate interface on the fatigue life of materials.In this paper,based on chemical analysis technology,microscopic observation technology and dynamic shear rheometer,the adhesive properties and fatigue properties of asphalt mastic-aggregate interface are studied.The main research results are as follows:(1)Three types of aggregates-limestone,diabase and granite were obtained by cutting,physical and chemical properties of aggregates was tested,and the chemical composition differences between different types of aggregates were analyzed.The analysis of the roughness of the aggregate and the density distribution of the structural depth was completed.(2)Three types of asphalt mastic using mineral filler(filler-asphalt ratio 0.5,1.0,1.5)were prepared,and asphalt mastic-aggregate-asphalt mastic specimen was produced.Based on the dynamic shear rheometer(DSR),the effect of the interaction at the aggregate-mastic interface on the viscoelastic properties of the material was explored.20 strain scanning test was carried out,and LVE limit strain value was used to evaluate the interface bond strength.Multi-temperature frequency sweeping test was carried out,WLF and Sigmodal equations were used to complete the main curve fitting to evaluate the viscoelastic properties of the asphalt mastic-aggregates system in a wide range of temperature and frequency.(3)The time sweeping test was used to test the fatigue performance of the aggregate-mastic system,and the influence of aggregate and filler-asphalt ratio factors on modulus attenuation was investigated.The theoretical framework based on S-VECD model was used to analyze the interface fatigue performance,and the C~*N index was used to calculate the fatigue life of specimens,the fatigue life-stress(strain)equation and curves were obtained.In addition,the damage characteristic curves(C-S curves)of each asphalt mastic-aggregate specimen were obtained,and the influences of aggregate type and stress(strain)level on the fatigue evolution behavior of the specimen were studied.The results show that the curve changes have good correspondence with the fatigue life.(4)Based on the the fatigue test data obtained by the constant stress(strain)modal test,The indoor fatigue prediction model of asphalt mastic-aggregate system was obtained,and the results show that there is a good correlation between the fatigue life and the initial strain and modulus of the material,and the model calibration accuracy of the constant stress model is higher than that of the constant strain model.In this paper,the viscoelastic behavior of asphalt mastic under different aggregate bonding conditions was studied,and the influence of interface characteristics between asphalt mastic and aggregate on fatigue property was investigated.Relevant research results can provide certain reference value for optimizing road materials,optimizing the design of filler-asphalt ratio,and improving interface adhesion and fatigue performance. |
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