| In this paper,the fracture healing performance of open graded asphalt mixture is studied.The self-made high viscosity asphalt and its open graded asphalt mixture are taken as the research object.The fracture healing tests of high viscosity asphalt and its prepared asphalt mixture are carried out by using force ductility test and semicircular bending(SCB)test.The effects of healing time,healing temperature,high viscosity agent content and gradation on the fracture healing performance of high viscosity asphalt mixture are studied Based on the distribution of asphalt aggregate on the fracture surface,the healing mechanism of open graded asphalt mixture is analyzed by using Python image processing technology.According to the relevant requirements of the specification,high viscosity asphalt was prepared with TPS high viscosity modifier,and its basic performance,dynamic shear(DSR)fatigue damage healing performance were tested.It was found that high viscosity asphalt has good fatigue resistance and micro damage healing ability.Firstly,in order to study the fracture healing performance of asphalt,a test method of asphalt fracture healing based on force ductility is proposed.The effects of healing temperature,healing time and high viscosity agent content on the fracture healing performance of asphalt are studied respectively.The fracture energy ratio and yield strain energy ratio are used as the healing index.The results show that the healing index of high viscosity asphalt increases with the increase of healing temperature and healing time.When the temperature exceeds the softening point of asphalt,the growth rate of healing index gradually decreases;the higher the content of high viscosity asphalt,the smaller the healing index.The fracture healing ability of modified asphalt is higher than that of SBS.Taking PA-13 open graded asphalt mixture as the main research object,the semi-circular bending(SCB)test is used to carry out the fracture healing fracture test of asphalt mixture.Before the test,the heating effects of microwave heating and oven heating are compared and analyzed.The oven heating healing test method is selected,and the critical load ratio and fracture energy ratio are taken as the healing evaluation indexes.The effects of healing temperature,healing time and high viscosity content on the fracture healing performance of asphalt mixture were studied.It is found that with the increase of healing temperature and healing time,the healing index of asphalt mixture increases;the higher the content of high viscosity agent,the lower the healing index;the healing index of different types of open graded asphalt mixture is PA-10 >PA-13 > PA-16,which indicates that the larger the nominal particle size is,the worse the healing performance of asphalt mixture is;finally,PA-13 is established according to the test results Time temperature binary linear prediction model of asphalt mixture.According to the different forms of asphalt mixture fracture surface,the aggregate damage degree(D)of mixture fracture interface is defined.The test shows that the larger the D value is,the worse the fracture healing effect of mixture is.Compared with high viscosity asphalt PA-13,70 # AC-13 and SBS AC-13 asphalt mixture,the D value of AC-13 asphalt mixture is less than PA-13,that is,compared with PA-13 mixture,AC-13 mixture has better fracture healing performance.Combined with Python image processing technology,the characteristics of fracture healing interface of open graded asphalt mixture are analyzed.Three fracture healing types of open graded asphalt mixture based on different fracture conditions are proposed: fusion type(asphalt asphalt fracture interface),adhesion type(asphalt aggregate fracture interface)and joint filling type(aggregate aggregate fracture interface),and different types of self-healing are analyzed mechanism.Finally,according to the research results,the scheme to enhance the healing performance of open graded asphalt mixture is proposed from the external conditions and the material itself. |
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