Research On Mixing Uniformity Of Asphalt Mixture Based On Simulation And Experiment

The mixer is the key component of asphalt mixing equipment.Its structure and process parameters directly affect the mixing uniformity and mixing efficiency of the mixture,and the mixing uniformity of the mixture is related to the service life of the asphalt pavement.Therefore,in order to optimize the working performance of the stirrer and improve the quality of asphalt pavement construction in our country,this paper takes a 4000 type stirrer as the research object,uses the method of combining theory,simulation and experiment to study the mechanism of each parameter of the stirrer in the mixing process,and master the relationship between the key parameters of the stirrer and mixing uniformity and mixing efficiency.It provides theoretical basis for the design and manufacture of stirrer.The mixer is the key component of asphalt mixing equipment.Its structure and process parameters directly affect the mixing uniformity and mixing efficiency of the mixture,and the mixing uniformity of the mixture is related to the service life of the asphalt pavement.Therefore,in order to optimize the working performance of the stirrer and improve the quality of asphalt pavement construction in our country,this paper takes a 4000 type stirrer as the research object,uses the method of combining theory,simulation and experiment to study the mechanism of each parameter of the stirrer in the mixing process,and master the relationship between the key parameters of the stirrer and mixing uniformity and mixing efficiency.It provides theoretical basis for the design and manufacture of stirrer.This paper firstly introduces the mixing mechanism of asphalt mixture,and theoretically analyzes the effects of parameters such as the ratio of the length to width of the mixer,the phase Angle of the mixing arm,the position of the asphalt feeding,the time of "dry mixing" and the filling rate of the mixing on the mixing uniformity of the mixer.According to the particularity of asphalt mixture mixing process,API plug-in suitable for mixing process was developed,a 3D model of a company’s mixer was established according to the original size,the initial distribution of aggregate was analyzed,and the mixing process of stirrers with different parameters was simulated by EDEM.The simulation results show that:(1)when the aspect ratio of the mixer is reduced,the dispersion coefficient of each component of the mixture tends to decrease.(2)When the mixing arm is placed alone,the order of mixing efficiency is just opposite to the order of mixture grading uniformity.The mixing efficiency of positive & positive 90° is the best,but the mixing uniformity is the worst.The mixing uniformity of forward & reverse 135° was the best,but the mixing efficiency was the worst.(3)The feeding position of asphalt affects the mixing efficiency of aggregate and the initial distribution uniformity of asphalt.The over-dispersed feeding position of asphalt reduces the mixing efficiency of aggregate,and the over-concentrated feeding position of asphalt reduces the initial distribution uniformity and mixing efficiency of asphalt.(4)The length of dry mixing time mainly affects the mixing efficiency of aggregate and asphalt,and the reasonable dry mixing time is 5～8 s.Finally,a field test was carried out on the 4000 agitator under different filling rates and mixing cycles,and the recommended values of mixing time and filling rates were obtained.Through the test,it was found that the asphalt and ore powder appeared axial end stacking phenomenon when the asphalt was fed to the axial single end of the asphalt.The change trend of the test results was consistent with the simulation,which proved the reliability of the simulation model.