Research On Rheological Properties And Application Of Hard Petroleum Asphalt

Under the background of the rapid development of transportation industry in China,rutting is becoming more and more serious due to the increasing number of heavy-duty vehicles,serious overloading and frequent high temperature weather.After comprehensively analyzing various rutting treatment measures,it is found that using hard petroleum asphalt to improve the rutting disease of asphalt pavement and increase the service life of the pavement is the most effective measure with the least investment.Compared with European countries,the research on hard petroleum asphalt in China mainly focuses on its high temperature performance,and the pertinence of relevant research is not sufficient,and the conclusions obtained do not effectively guide the actual construction.There are also different conclusions in the study of low temperature rheological properties and fatigue properties of hard petroleum asphalt.The existing low temperature evaluation indicators of asphalt have insufficient applicability for hard petroleum asphalt,which limits the promotion of hard petroleum asphalt.Therefore,this paper uses the theory of viscoelastic mechanics,starting from the rheological properties of asphalt,to study the high-temperature rheological properties,medium-temperature fatigue properties and low-temperature rheological properties of hard petroleum asphalt.The evaluation indexes of high temperature and low temperature of hard petroleum asphalt were explored by various analysis methods,and the comprehensive performance of each hard petroleum asphalt was further studied.The road performance of hard petroleum asphalt mixture with different structure forms was explored,and the hard petroleum asphalt was applied in the cold and arid area in northwest China.The main research contents and conclusions are as follows:Firstly,the viscose-temperature curve of hard petroleum asphalt was obtained through the Brinell viscosity test at different temperatures combined with the improved REFUTAS formula,and the construction temperature of hard petroleum asphalt was clarified.The temperature and frequency scanning tests of hard petroleum asphalt under different aging states show that the high-temperature viscoelastic properties of hard petroleum asphalt can reach the level of modified asphalt.Repeated creep recovery tests with multiple stresses show that hard petroleum asphalt can keep its structure stable and its viscoelastic properties unchanged in a certain temperature range under low strain.Combined with the latest high-temperature asphalt PG classification,it is found that 30#hard petroleum asphalt can meet the requirements of medium traffic grade,and 50#hard petroleum asphalt can meet the requirements of light traffic grade.Using the method of saliency analysis,the saliency relationship between factors such as label,oil source,aging degree and various high temperature indicators was studied.Through LAS tests at different temperatures,the stress-strain relationship under repeated loading was obtained,and combined with the VECD model to evaluate the fatigue characteristics of hard petroleum asphalt.It shows that hard petroleum asphalt can exert the same damage resistance as modified asphalt under suitable working temperature.Different hard petroleum asphalt is suitable for different load levels,so it is necessary to consider the load level of the pavement to select hard petroleum asphalt in the design of hard petroleum asphalt pavement.The correlation between the strain corresponding to the stress peak and the fatigue life is established,and the fatigue performance of hard petroleum asphalt can be quickly evaluated through the peak stress strain.Based on the BBR test,comprehensively considering the low-temperature deformation and low-temperature stress relaxation of hard petroleum asphalt,combined with the Burgers model to study the low-temperature evaluation index of hard petroleum asphalt,and the viscoelastic parameters based on the Burgers model were obtained.The low temperature evaluation indexes of hard petroleum asphalt,such as relaxation time(λ),new low temperature evaluation index m(t)/S(t)and low temperature comprehensive compliance parameter(J_C),were further constructed,and the rationality of each evaluation index was verified through the trabecular bending test of asphalt mixture.The change of aggregation state of hard petroleum asphalt with temperature was studied by DSC experiment,and the heat flow curve and glassy transition temperature of hard petroleum asphalt were obtained.With these as reference factors,the low temperature evaluation index of hard petroleum asphalt was systematically studied by using grey correlation theory.The results show that the creep rate m and the relaxation timelare the indexes based on the glassy transition temperature T_g,which can better evaluate the low temperature performance of asphalt.The high and low temperature evaluation indexes of hard petroleum asphalt were analyzed by using principal component analysis method,and the comprehensive performance of hard petroleum asphalt was objectively evaluated.Two structures,AC-13 and ATB-25,were selected to verify the pavement performance of the hard petroleum asphalt mixture.It is found that the hard petroleum asphalt mixture still has good water stability after freeze-thaw cycle through the Marshall stability test and freeze-thaw splitting test.Through the rutting test,it is found that the high temperature deformation resistance of hard petroleum asphalt mixture is consistent with the relative deformation rate and dynamic stability,which indicates that the hard petroleum asphalt mixture has excellent high temperature performance.The low temperature crack resistance of hard petroleum asphalt was explored through low-temperature bending test and low-temperature creep test,which shows that the upper hard petroleum asphalt mixture can meet the low temperature crack resistance requirements at temperatures above-9.0℃,and the base hard petroleum asphalt mixture can meet the low temperature crack resistance requirements between-9.0℃and-21.5℃.In order to further explore the pavement performance of hard petroleum asphalt and verify the correctness of the laboratory test results in this article,the DD3 contract section of Dundang Highway was selected to pave the hard petroleum asphalt test section,and the rationality of the hard petroleum asphalt test road was verified through the field test results,which provided a practical engineering case for the promotion of hard petroleum asphalt.At the same time,it also proves that the high temperature,medium temperature and low temperature evaluation system of hard petroleum asphalt and its mixture obtained in this paper from the perspective of rheology is reasonable.