Research On Performance Of SEBS/PPA Compound Modified Asphalt And Mixture

With the increase of road traffic and vehicle load,the performance of asphalt binder has higher requirements,therefore the application and research of modified asphalt are paid more attention.SEBS which has excellent photo oxidation resistance,thermal stability and weather resistance has been widely used in polymer field.In this paper we mixed SEBS with low-cost and easy-to-process polyphosphoric acid(PPA)into the asphalt for compound modification,and developed a compound modified asphalt with excellent comprehensive performance.In this paper,Zhongjiao 70#matrix asphalt is used as raw material,SEBS and PPA are used as modifiers,furfural extracted oil and dibutyl phthalate(DBP)are used as additives to prepare compound modified asphalt.In order to obtain the best ratio of various admixtures of compound modified asphalt,firstly,the orthogonal experiments were used to study the effects of modifier content and additive content on the performance of compound modified asphalt,and the results show that the degree of influence on penetration of compound modified asphalt is:PPA>SEBS>DBP>furfural extract oil;the degree of influence on temperature sensing property is:PPA>SEBS>furfural extract oil>DBP;the degree of influence on softening point is:PPA>SEBS>furfural extract oil>DBP;the extent of influence on ductility is:PPA>SEBS>furfural extract oil>DBP.Then,the TOPSIS method is used to calculate the ideal solution proximity CI for each group of orthogonal test data,and using it as the evaluation index to get the best ratio of compound modified asphalt:6.0%SEBS+0.5%PPA+4.0%furfural extract oil+1.0%DBP.Moreover,Considering the influence of the modification process on the performance of the compound modified asphalt,this paper adopts the response surface methodology and central composite design to optimize the modification process.According to the results of the central composite design test,the overall desirability value(OD)of each group of tests is calculated,the OD value,shear temperature(X1),shear rate(X2),shear time(X3)were subjected to multiple nonlinear regression to obtain OD=0.530.53X1-0.53X2-0.47X3-0.01X12-0.28X22-0.68X32-0.32X1X2-0.54X1X3-0.74X2X3,then,the effect surface is drawn according to the regression equation and the optimized modification process is:shear temperature 163℃,shear rate 4300r/min,shear time 55min.In order to further study the influence of SEBS and PPA content changes on the performance of compoound modified asphalt,this paper gradually changes the content of SEBS and PPA and tests its performance.The boiling test shows that the compound modified asphalt has good adhesion to the aggregate;The storage stability test shows that the increase of the SEBS content will increase the segregation of the compound modified asphalt,while the PPA content can improve its storage stability;Viscosity test shows that both SEBS and PPA can significantly increase the viscosity of the compound modified asphalt,moreover,SEBS has a more significant effect on viscosity,When the content of SEBS reaches 6%and the content of PPA reaches 1.5%,the viscosity of the compound modified asphalt at 135℃ exceeds 3.0Pa-s and the viscosity is too high for normal production.Using a dynamic shear rheometer to test the compound modified asphalt before and after aging,it was found that the addition of SEBS and PPA can significantly improve the high-temperature rutting resistance of the asphalt binder.As the content of SEBS and PPA increases,the creep recovery ability of asphalt binder at 60℃ gradually increases and Rdiff gradually decreases,it shows that the elastic recovery performance of the compound modified asphalt is improved and the nonlinear viscoelasticity is weakened,the nonrecoverable creep compliance Jnr gradually decreases with the increase of SEBS content and PPA content,the Jnr-diff value of compound modified asphalt are all less than 75%,except for 0.5%PPA modified asphalt,all other groups of modified asphalt meet the performance requirements of AASHTO standard traffic.After short-term aging and UV aging,each group of compound modified asphalt showed a decrease in phase angle,an increase in rutting factor,the elastic component in the compound modified asphalt is increased,the viscosity component is reduced,and the high-temperature anti-deformation performance is improved.Compared with SEBS,PPA can more effectively improve the performance of compound modified asphalt after short-term aging,the UA aging resistance of compound modified asphalt is more sensitive to the change of SEBS content,SEBS can effectively improve the UA aging resistance of asphalt.DSC test shows that glass transition temperature of compound modified asphalt(Tg)gradually decreases with the increase of SEBS content,and gradually increases with the increase of PPA content,SEBS can effectively improve the low temperature performance of compound modified asphalt,but the improvement effect gradually decreases after the content is higher than 4%,however,the addition of PPA has a negative impact on the low temperature performance of compound modified asphalt.The comparison of the characteristic peak distribution of the asphalt binder before and after modification by infrared spectroscopy shows that there are no new characteristic peaks in the binder before and after modification,so the compound modified asphalt is mainly physical modified.Finally,the AC-13 grade was selected to verify the performance of the compound modified asphalt.The Marshall test method was used to determine the optimal asphalt content of the matrix asphalt,SBS modified asphalt and SEBS/PPA compound modified asphalt.The results of rutting test and low temperature trabecular bending test show that the high temperature performance and low temperature performance of the compound modified asphalt is slightly lower than that of SBS modified asphalt,but it is significantly improved compared to the matrix asphalt.The freeze-thaw split test and the waterimmersed Marshall test both show that the resistance to water loss of the compound modified asphalt is better than that of SBS modified asphalt and matrix asphalt.After long-term aging,the resistance to water loss of compound modified asphalt is reduced the least,this shows that its anti-aging ability is better than SBS modified asphalt and matrix asphalt.