Research On Composition Design And Performance Of Polyurethane Modified Asphalt

In order to improve the performance of asphalt,researchers have conducted a lot of research on asphalt modifiers.Modified materials have been extended from rubber,fiber,PE,etc.to a variety of polymer materials,but the problem of asphalt pavement diseases is still relatively serious.Therefore,exploring new modifiers is still of great significance.This article intends to use the excellent high,low temperature and mechanical properties of polyurethane（PU）to modify 70#asphalt,design the proportion of modified asphalt components,and use 70#asphalt and SBS modified asphalt as a control group to study and evaluate the macroscopic properties of PU modified asphalt.The main research work is as follows:（1）According to the basic index of PU,the index of road use and the basic performance index of PU modified asphalt,one product is selected,and the content is determined to be 15%～30%.In order to obtain the best preparation process,the orthogonal test method is used to optimize the combination of process parameters,and the best process parameters to improve the high temperature performance are obtained.（2）The paper uses FTIR to reveal the mechanism of PU modified asphalt.After PU is incorporated,the absorption peaks of asphalt at 3675cm-1 and 1018cm-1disappear,and the absorption peak of PU at 2271cm-1 disappears.The PU modified asphalt has a new absorption peak at 1723cm-1,indicating that PU mainly reacts with organic compounds containing─OH and C─O in the asphalt to exert its modification effect.At the same time,the phase structure was observed with a Fluorescent Microscope,and it was found that the critical blending amount of PU was 15%.After the blending amount was greater than 15%,the modified asphalt showed a PU-asphalt bicontinuous phase.（3）According to the DSR test results,theη,G*,δ,rutting factor and VTS index of7 kinds of asphalt are analyzed,and the viscoelastic properties of asphalt are studied based on the dissipation energy theory.The results show that PU can increase the elastic component in asphalt,improve its mechanical strength and resistance to rutting deformation.At 58℃,theηand rutting factor of 5%PU modified asphalt are increased by 23%,7%compared to 4%SBS modified asphalt,respectively;the temperature sensitivity of PU asphalt also has an improvement effect,the VTS index of 15%to 30%PU modified asphalt is better than SBS modified asphalt.（5）According to the BBR test results,the bending stiffness S,creep rate m,m/S and DER index of 7 kinds of asphalt are analyzed,and the low temperature creep characteristics of asphalt are analyzed based on the Burgers model.The results show that PU can improve the low-temperature flexibility of asphalt,reduce its low-temperature elasticity,make the asphalt more easily release the energy generated by temperature stress,increase the dissipation energy,reduce the storage energy,improve the low-temperature relaxation performance of asphalt,The low-temperature rheological index of 15%～30%PU modified asphalt is better than SBS modified asphalt;in low temperature environment,the elastic modulus（E₁）of 5%PU asphalt is lower than 70#asphalt and SBS modified asphalt,its ability to release temperature stress through deformation is better than SBS modified asphalt.（6）The road performance of 5 kinds of asphalt mixtures was studied by rutting test,trabecular bending test,submerged Marshall test and freeze-thaw splitting test.The results show that PU can improve the high and low temperature performance and water stability of the mixture.The dynamic stability,bending strain and Marshall index of20%～30%PU modified asphalt mixture are better than SBS modified asphalt.The thesis studies PU modified asphalt from the perspective of microstructure and macro performance,and analyzes the rheological properties of PU modified asphalt based on the relevant theory of rheology.At the same time,the performance index of the designed 20%～30%PU modified asphalt is better than SBS modified asphalt,which has the value of popularization and application.