Experimental Study On Master Curve Of Failure Strength Of Asphalt Mixture

Under different test conditions,the mechanical properties of asphalt mixture are different due to different test temperature,loading rate,stress state and other factors.The different mechanical parameters will further affect the pavement structure layer stress,strain and other calculation results,thus affecting the asphalt pavement design.Therefore,it is of great significance to study the mechanical laws of asphalt mixtures under different stress modes.First of all,this paper introduces the current commonly used asphalt mixture mechanical properties test and research methods,and developed the test program.The mechanical properties of asphalt mixture under different test temperatures and loading rates were obtained by uniaxial compression test and direct tensile test.Uniaxial compression tests were carried out under four temperature conditions and seven loading rates.Direct tensile tests were carried out under 7 temperature conditions and 7 loading rates.After obtaining the time,displacement and load parameters of asphalt mixture in uniaxial compression test and direct tensile test,the strength,stiffness modulus and strain data of asphalt mixture specimen in the failure stage and elastic deformation stage were obtained.The effects of loading rate and temperature on the mechanical parameters of asphalt mixture were considered separately,and the similarities and differences of mechanical parameters under the two test methods were analyzed.According to the Mohr-Coulomb theory,the failure strength parameters of asphalt mixture under two test methods were used to calculate the bonding force and internal friction Angle of asphalt mixture under different test temperatures and loading rates,and the law of its change with temperature and loading rate was analyzed.Finally,based on the time-temperature equivalence principle,the main curve fitting of the mechanical parameters of asphalt mixture under two stress states is carried out.WLF equation was used to calculate the shift factor,and linear model and sigmoid model were used to fit the main curve after translation based on the reference temperature.The results show that the uniaxial compressive failure strength,direct tensile failure strength and cohesive force of asphalt mixture increase with the increase of speed and decrease with the increase of temperature,and got very good master curve fitting results.However,due to the lack of research in this area,further research and verification are still needed.