Study On Asphalt-filler Interaction And Prediction Of Asphalt Mastic Performance

Study of multi-scale modelling of asphalt materials regards asphalt mixture as a composite material consisting of viscoelastic asphalt mastic,elastic aggregate with different particle sizes and a small amount of voids.Although the asphalt mastic accounts for only 10%of the total mixture mass,its properties significantly affected the performance of the mixture.In asphalt mixture,the asphalt mastic acts as the real binder Therefore,it is very important to study the dynamic mechanical properties of asphalt mastic and the factors that influenced it.In addition,it is necessary to fully understanding the predict asphalt dynamic mechanical properties and fatigue times based on the composition of mastic and the interaction between asphalt and filler.The rheological properties of asphalt mastic is not only affected by asphalt,but also filler,filler volume fraction and asphalt-filler interaction.Investigation of linear viscoelastic strain of asphalt mastic showed the linear viscoelastic strain of virgin asphalt is more sensitive to loading frequency and has significantly bigger value of linear viscoelastic strain than modified asphalt.Linear viscoelastic strain decreases with the increasing of filler volume fraction.Black diagram of asphalt mastic showed that phase angle-complex modulus curve of different temperatures can not be well superimposed on a smooth line,which mean the time-temperature equivalence principle(TTSP)is not suitable for asphalt mastic.Therefore,construction of complex modulus and phase angel master curve is based on the least square method of MS Excel.The fitting analysis of complex shear modulus master curve showed that the 2S2P1D and generalized Sigmoidal model have the minimum fitting error.The interaction between asphalt and filler results in the formation of structural asphalt on the surface of filler.Stronger the interaction is,higher the relative content of structural asphalt is,and greater the influence of filler on asphalt mastic.The asphalt-filler interaction was evaluated by Palinee-C,complex shear modulus coefficient(35)G~*,complex viscosity coefficient(35)?~*and Einstein coefficientK_E.It was found that asphalt,filler properties and filler volume fraction had some influence on asphalt-filler interaction.The reciprocal creep compliance method was used to determine the criticalfillervolume fraction of asphalt mastic.The result showed that stronger of theasphalt-fillerinteraction,smaller the critical filler volume fraction in mastic.Generalized self-consistent model,four-phase self-consistent model and particle interferingmodelwereappliedto predict the complex shear modulus of asphaltmastic.The result showed that the prediction error wasaffected by thefiller volume fractionand asphalt binder.Prediction error of the models increaseedwith the increasingof filler volume fraction,and modified asphalt mastic showed biggerprediction error than that of the virginasphalt.To simplify the calculation and improve prediction accuracy,amodified generalized self-consistent model is used to calculate the complex shear model of asphaltmastic,in the new model,Palierne-Cwasused to correct the filler volume fraction.The result showed that modifiedgeneralized self-consistent model can significantly improve the prediction accuracy.Based on viscoelastic continuous damage theory,the fatigueof asphalt andmasticwas predicted.It was found that asphalt,filler volume fraction andasphalt-fillerinteraction had significant effects on fatigue of asphalt mastic.The type of filler hadlittle effect on the fatigue times of asphalt mortar.The skeleton void filling method was used to design asphalt mixtures.Keeping the aggregate skeleton and asphalt-aggregate ratio unchanged,the effect ofmasticon dynamic mechanical properties of asphalt mixtures was analyzed.The result showedthat,in low frequency region,filler volume fractiondisplayedsignificant effect of on the dynamic modulus of mixtures.Complex modulus of mixtures increases with the increase of filler volume fraction.In low frequency region,asphalt binder showedsignificantly affectedondynamic mechanical properties of mixtures,while in high frequency region,its showed less affect.With the increase of filler volume fraction,the influence of asphalt type on dynamicmechanical properties of mixtures decreasedgradually.The type of filler hadlittle influence on the dynamic mechanical properties of the mixture.