Research On Anti-Rutting Performance Of Direct Coal Liquefaction Residue Modified Asphalt Mixture

Direct Coal Liquefaction Residue(DCLR)is a by-product of coal direct liquefaction technology,and its output accounts for about 30% of the original coal.With the promotion and application of direct coal liquefaction technology,the output of DCLR is getting larger and larger,and its disposal and utilization problems need to be solved.Based on the material properties of DCLR,DCLR has the potential to be developed into asphalt anti-rutting agents.Therefore,based on the study of high temperature deformation characteristics of DCLR modified asphalt mixture and the proposed model of DCLR modified asphalt mixture rutting,this paper evaluates the anti-rutting performance of DCLR modified asphalt mixture.Firstly,the high temperature deformation characteristics of four kinds of asphalt mixture(composite DCLR modified asphalt mixture,DCLR modified asphalt mixture,SBS modified asphalt mixture and SK-90 asphalt mixture)were studied.Through the variable temperature and variable pressure indoor rutting test,it was found that the high temperature performance of the four asphalt mixtures was: composite DCLR modified asphalt mixture > DCLR modified asphalt mixture > SBS modified asphalt mixture > SK-90 asphalt mixture.Using variance analysis,it is found that the effect of temperature change on the anti-rutting performance of asphalt mixture is greater than the load change.Through the triaxial repeated load test,it is found that the flow number and nonlinear fitting index are negatively correlated and positively correlated with temperature and load,respectively,indicating that both the flow number and the nonlinear fitting index can reflect the anti-deformation ability of the asphalt mixture,but Under the condition of heavy load high temperature(1.0 Mpa,65 °C or above),the nonlinear fitting index is recommended as an index to evaluate the anti-deformation ability of asphalt mixture.Secondly,the four-unit five-parameter model is modified based on the triaxial repeated load test.The rheological parameters of the four asphalt mixtures are calibrated by fitting the rheological model with the three-axis repeated load test data,and simulated by ABAQUS.The indoor rutting test verified the validity of the rheological parameters.The results show that the fitting degree is between 0.78 and 0.991,which proves that the fitting result can describe the creep curve of the triaxial repeated load test;the maximum error ratio of the rut depth obtained by the two test methods is less than 13.2%,and the rheological parameters are verified.Effectiveness.Finally,the ABAQUS and APAD simulations were used to calculate the rutting behavior of the four asphalt pavements with a design life of 1 year,2 years,5 years,10 years and 15 years.It is found that the composite DCLR modified asphalt mixture and DCLR modified asphalt mixture can reduce the rut depth of 55.9% and 42.2% compared with SK-90 asphalt mixture,indicating that the composite DCLR modified asphalt mixture and DCLR modified asphalt mixture are at high temperature.The roads with large traffic volume in the area have good rutting performance;comparing the rut depth of the asphalt surface layer measured bythe APAD of the four asphalt roads and the rutting depth calculated by the ABAQUS simulation,the maximum deviation value is found to be 4 mm,and the maximum deviation percentage is 18.1%,which proves the proposed finite element rutting model is highly effective.