Research On Micromechanical Model And Milling Simulation Of Asphalt Mixture Based On Old Asphalt Pavement

With the rapid development of highway construction in China,many high grade asphalt Pavements built in the early stage have gradually entered the maintenance period,there are more and more Pavement maintenance operations.As an important Part of asphalt Pavement maintenance,Pavement milling is an important renewable resource.Faced the increasingly scarce stone resources,how to improve the recycling rate of old Pavement milling mixture to reduce the waste of resources,reduce the cost of road maintenance,has become one of the most urgent problems to be solved in the industry.At present,in the research on improving the recycling rate of milling materials,the main research is the special processing of milling materials.This method only studies the milling material itself,but ignores the important influence of the cutter head on the milling material in the old Pavement milling process.At present,the research on Pavement milling mainly focused on the milling Parameters of milling machines.There is almost no research on asphalt Pavement crushing.Therefore,it is very necessary to study the asphalt Pavement milling for different types and service years.In view of the fact that the actual Pavement milling test equipment is very expensive,time-consuming and laborious,and the process is multifarious,this Paper uses the discrete element method to simulate the old asphalt Pavement milling process,in order to find out the milling Parameters of the cutter head when the Pavement milling effect is the best.Firstly,according to the principle of asphalt simulated aging,the indoor asphalt aging time corresponding to the actual asphalt Pavement service life is obtained.The AC-16 asphalt mixture specimen corresponding to different service years are made using the aged asphalt,and uniaxial compression and indirect tensile test were performed in laboratory.Then,two micro-mechanical models of asphalt mixture and uniaxial compression and indirect tensile test were constructed.The Parameters of two kinds of asphalt mixture contact models were calibrated based on the results of uniaxial compression test in laboratory,and the P model was determined to be the best asphalt mixture model after the comParison and analysis with the results of indirect tensile test in laboratory.Finally,the 3D model of the milling cutter headwas established,and the milling process of the old asphalt Pavement was simulated.The influence of the cutting speed and cutting depth on the force of the cutter head was analyzed,Analysis shows : When milling the old asphalt Pavement,for the AC-16 asphalt mixture corresponding to the actual Pavement service life of 11~12 years,the cutting angle is 42,the cutting speed of the cutting head is 0.5m/s,and When the cutting depth is within the range of20 mm,The cutter head breaks less coarse aggregates,which is beneficial to improve the recycling of the milling material.