Unified Characterization Of Strength And Fatigue Characteristics Of Rubber Asphalt Mixture Under Different Loading Modes

With the rapid development of China’s automobile industry,the disposal of waste tires has aroused widespread concern.It is found that the preparation of rubber asphalt from waste tires into rubber particles is an effective and environmentally friendly treatment method.Therefore,rubber asphalt mixture as pavement material is currently a research hotspot.At present,the strength parameters and fatigue resistance evaluation of asphalt pavement structure design are mostly obtained through laboratory tests such as direct tension test,uniaxial compression test and indirect tension test,but the strength and fatigue test results of asphalt mixture obtained by different test methods are quite different.It is impossible to evaluate its anti-destructive ability and durability,which leads to the randomness of the strength and fatigue parameters in the design of the pavement structure.Based on this,this paper mainly carried out the following three aspects of research:（1）Three kinds of rubber powder specifications（40 mesh,60 mesh,80 mesh）and five kinds of rubber powder contents（15%,17%,19%,21%,23%）were selected in the experiment.The influence of rubber powder contents and contents on rubber asphalt performance was analyzed by 180℃ rotational viscosity,penetration,ductility,softening point and other parameters.The rubber powder contents and specifications in rubber asphalt production were 21%and 40 mesh respectively;the Marshall test method was used to determine that the best asphalt asphalt ratio of rubber asphalt mixture was 7.2%.（2）The uniaxial compression strength test,indirect tensile strength test and direct tensile strength test were carried out at different temperatures and loading rates,and the power function of strength with loading rates was revealed at different temperatures.Based on the relationship between strength ratio and loading rate ratio of three direct tensile,uniaxial compression and indirect tensile tests,a unified strength model S/S₀=（v/v₀）^{5.48×10-5T-0.00661T+0.31507} of rubber asphalt mixture with different loading modes was established considering the effect of loading rate and temperature.The model can improve the efficiency of laboratory test of rubber asphalt mixture and promote the design of rubber asphalt pavement.（3）The stress ratio related to the loading rate is defined as the velocity dependent stress ratio.Based on the nominal stress ratio,the fatigue tests of rubber asphalt mixture under different loading modes are carried out.The unified equation N_f=（1/t_s）^5.35593 of fatigue life under different loading modes is established based on the idea of velocity dependent stress ratio.The uncertainty and uniqueness of the fatigue performance of rubber asphalt mixture under different loading modes are solved.So as to provide a theoretical basis for the anti fatigue design of rubber asphalt pavement.Generally speaking,the studies in this paper are believed to provide some ideas for structural resistance design of rubber asphalt pavement and provide reference for durable asphalt pavement design.