Study On The Aging And Regeneration Properties Of Asphalt Based On SHRP Test

The aging and recycling of asphalt is related to the service life,maintenance and recycling of asphalt pavement.The study of its performance can provide a reference basis for the prevention and control of asphalt pavement diseases,the construction of high-performance asphalt pavement and the recycling of aging asphalt mixture.Therefore,in order to study the aging and recycling performance of asphalt,a series of asphalt tests in the Strategic Highway Research Program(SHRP)are carried out to carry out the performance test research of aging asphalt and recycling asphalt.Firstly,the asphalt with different aging degree was prepared by rotating membrane oven test and pressure aging test.Combined with the aging asphalt milled and extracted from the aging asphalt pavement,the rotating viscosity test,dynamic shear rheological test,bending beam creep test and direct tensile test were carried out respectively to explore the change rule of aging asphalt performance;Secondly,different amounts of asphalt regenerant and AH-90 asphalt were added into the extracted aged asphalt to prepare reclaimed asphalt.Through SHRP test,the initial performance,short-term aging and long-term aging performance of various kinds of reclaimed asphalt were analyzed.The influence of the amount of regenerated asphalt on the performance of asphalt was studied.The regeneration effects of the two regeneration methods were compared and the PG grade of various kinds of reclaimed asphalt was determined;Finally,based on the climate and pavement structure of some cities in Jilin Province,the applicability of recycled asphalt is discussed based on the PG classification method,and the optimal amount of recycled asphalt is determined by constructing the AHP model for the performance evaluation of recycled asphalt.The main research conclusions are as follows:(1)The aging asphalt performance test shows that the relationship among asphalt high and low temperature performance test results(z),indoor aging test time(T)and asphalt performance test temperature(t)is: ln z=A+BT ^ 0.5+Ct;Compared with two indoor aging methods,rotating film oven aging for 301 min can replace SHRP standard long-term aging test;By comparing the indoor aging test with the actual engineering aging effect,it is suggested to extend the SHRP standard long-term aging test time to simulate the performance change of asphalt in the actual engineering aging about 8years.(2)The performance test of reclaimed asphalt shows that: with the increase of the amount of regenerant and AH-90 new asphalt,the medium temperature fatigue performance and low temperature crack resistance of reclaimed asphalt are better,and the high temperature rutting resistance is opposite;Compared with the two regeneration methods,the regeneration effect of the regenerant is better than that of AH-90 new asphalt,about 3-4 times of that of AH-90 new asphalt;The high temperature grade of regenerated asphalt PG changes significantly with the mixing amount,and the medium and low temperature grades change slightly.It is suggested to further refine the medium and low temperature grade of regenerated asphalt PG to evaluate the medium and low temperature performance of regenerated asphalt under different mixing amounts.(3)The research on the applicability of recycled asphalt content shows that the high temperature grade of all kinds of recycled asphalt can meet the high temperature rutting resistance requirements of asphalt within the depth range of 0～22cm,but the low temperature grade can only meet the low temperature crack resistance requirements within the depth range(10～22cm)of pavement flexible base in Ji’an,Siping,Yanji and Changchun.The adaptability of recycled asphalt in low temperature performance is poor,It is necessary to further explore ways to improve the low-temperature performance of recycled asphalt;Based on the AHP model,the optimum performance of reclaimed asphalt with 20% regenerant and 80% AH-90 was obtained.