Research Of Inorganic Filler On The Properties Of Asphalt Mastic By Meso-mechanical Method

Asphalt binder is made from fine aggregate and asphalt mortar. Bonding mortar is madefrom asphalt mortar and mineral powder. Because there is tenuous mineral powder in thebonding mortar, we can deal the bonding mortar as particle-filled composite to some degree.The irregular shape and distribution feature of tenuous mineral powder also will affect themechanical properties of asphalt mortar. It is stochastic for the macroscopic properties ofasphalt mortar due to the influence of many factors. Because of the irreversible forming way,some test indexes of mortar present a little more randomness when conducting mortarperformance testing, it is mainly due to the random distribution of internal structure. Usingmesomechanics research method can not only be used to make the reconstitution of internalstructure of asphalt mortar come true, but also exactly analyze the failure mechanism andviscoelastic strain characteristics of asphalt mortar and binder.In experiment test, conventional experimental measurements conduct only-image testanalysis of mixture and binders from the point of only-image study, there is great differencebetween the specialty of the internal structure of mixture and evaluation indicator ofmacroscale because of the randomness of internal structure of the material. Moreover, due tothe limit of analysis tool, empirical method need vast experiments, which is based onphenomenon. When using macro-index to evaluate and research the performance ofbituminous mixture,it will cost enormous manpower, financial and material resources, alsothere is a little more variability and bad reproducibility of the test result. However, themesomechanics analytical method can not only avoid many experiments, but also analysisthe internal mechanics reaction of mortar deeply from meso-scale. So the analysis ofmicrostructure of mortar is the precondition of researching the failure characteristics ofbituminous mixture. To conduct a model reconstitution of the asphalt mortar constructionwith microscomic modeling approach, build a real physical model combining theory and testresult, and then reveal the macroscopic response caused by the microstructure change of asphalt mortar, which has important theoretical significance and engineering applicationprospect.This paper combined with the National Natural Science Foundation of China(51278222)"The study of anisotropic properties of asphalt mixture based on digital imageprocessing technology ", investigating the filler particles analyzed the impact law on theperformance of asphalt mortar, mainly achieved the following results:1Taking high shear agitation method can effectively disperse the filler particles,prepared the asphalt mortar with consistent performance. Laser particle size analysis methodcan quickly and accurately analyze the filler gradation composition, provides a fast andeffective method to determine the filler particles such as mineral gradation.2The study of prediction model of the asphalt mortar viscosity found that the viscosityof asphalt mortar increases gradually with filler volume fraction increases, in the early caseof small filler content showed a linear growth trend, and the relative viscosity growedrelatively slow. When the filler content exceeds the critical volume fraction, the mortarrelative viscosity increased with a nonlinear sharply trend. At this point, small changes involume fraction of the filler may cause sharp increase in the viscosity of mortar. And finallythe mortar flow is stopped, the relative viscosity approaches infinity. Compared theprediction results of Frankel equation and Einstein equation showed that when the fillercontent is less the Einstein equation predictions agree well with the experimental test results,and Frankel equation predictions results at low levels significantly lower than the Einsteinequation predictions results. Shows that the Einstein equations has a better accuracy mortarviscosity prediction at a low volume fraction content. Identified mortar viscosity predictionmethod and the applicability of different prediction models, help to improve the asphaltmortar predictive accuracy of viscosity.3Improvement of particles peripheral windowing method saves sample building valuecomputing time. Contrast the computation time of this improved method and the discoveryof existing methods,the consumed time was little difference between the improved methodand the original method when the area content in the lower level, but when the particle sizeexceeds40%the improved method of calculating consumption significantly reduced which indicate that particles peripheral windowing method can improve the computationalefficiency. The coordination number of the particles in asphalt mortar showed the stepwisegrowth trend with the increasing of the coating thickness, The coordination numberincreased with the coating thickness increasing. And the average coordination numbergradually increased with area content increases. The study of distance between the particlesurface shows the minimum surface distance between the particles gradually decreases withthe content of filler volume increasing. Meanwhile, a small spacing between the particlesurface significantly increased the frequency of occurrence, suggesting that particles beganto slowly form a skeleton structure with supporting role of friction.4. Particle shape and thickness of the asphalt mortar will affect the internal stressdistribution characteristic, when the oval-shaped particles filled with asphalt, the internallevel tensile stress was the maximum. Indicate the presence of flat particles will increase thestress concentration within the mortar. Low modulus flexible particle reinforced asphaltmortar is also cause stress concentration, then mortar concentrated stress on the particlemodulus more sensitive to changes. The ultimate bearing capacity and tangent modulusasphalt mortar increased with strain rate showed a log-linear growth trend, inorganic fillerscan enhance the ultimate bearing capacity and tangent modulus, and boosting asphaltmixture fatigue performance. Creep properties of the asphalt mortar analysis showed thatmore angular particles helps to reduce the viscosity flow deformation of asphalt mixture,thus ensuring asphalt good high temperature stability.