The Mechanical Properties Study Of Rubber Powder Modified Asphalt Mixture

The traditional asphalt pavement design method and Superpave design method make an research on the mechanical properties of mixed asphalt from macroscopic perspective. Although macroscopic mixed asphalt is close, functional performance is great difference in research. The reasons for this phenomenon is that effects of microstructure of mixed asphalt are ignored in research and useless, so actual deformation of material and destroying mechanism are not disclosed. Therefore, on asphalt mixture of micro structure and macro mechanical properties of asphalt mixture has become an international research focus.This paper focuses on crumb rubber modified asphalt mixture mechanical properties,with the macroscopic structure and microstructure structure mechanical properties of asphalt mixture,Established the virtual experiment model of rubber powder modified asphalt mixture micromechanics architecture and elaborated the relationship of the internal structure and the external load- deformation,in order to reveal the stress mechanism of asphalt mixture,for the engineering practice to provide some theoretical guidance. Through indoor experiment and numerical simulation, draw the following conclusions:First, through the indoor experiment analysis of crumb rubber, SBS and common asphalt mixture according to the preparation of the mixture sample grouping in three point bending test, and each specimen are respectively in three loading rate loading, that their deformation and force - time curve, then compared the result of three bending beam test and semicircle bending test. The results showed that: with the same kind of loading rate, the tensile cracking performance of the crumb rubber asphalt mixture is better than the other kind of asphalt mixture, and the deformation of destruction is smaller; the stress and stiffness modulus of crumb rubber asphalt increases with loading rate, strain decreases; the bending strength ratio of the three point bending beam test and semicircle bending test of the crumb rubber asphalt mixture is close, about 1.03.Secondly, based on the image analysis technology, the obtained image processing is introduced into the finite element method, as a numerical simulation model, the model of this way can more accurately reflect the aggregate and asphalt mixture distribution. On the basis of this model the model of three point bending test numerical simulation, with the test load data as model boundary conditions.The conclusion is drawn that the numerical simulation results and the experimental results is close to.Finally, in the above model, it is applied with different rate of loading, to analysis the meso structure stress and strain distribution of the asphalt mixture of different rate, as well as the aggregate and asphalt's stress and strain condition. The results showed that: there is the discontinuities inner asphalt mixture in the distribution of stress and strain, which aggregate assumed stress than asphalt assumed by the stress, the stress of aggregate total stress value proportion is larger, but the aggregate values of strain is smaller, bitumen bear most of the strain; in the model the maximum strain position and indoor test of crack location is close to; in the local study ,it is found that, with the increase of loading rate, pitch node stress value and the aggregate stress value increases; in the crack location, aggregate and asphalt stress respectively as the rate increases and the amplitude is close to;but the strain of aggregate node and asphalt node is different,which Appeared serious disharmonies.