Effect Of Mixing Temperature On Long-term Aging Of Asphalt

The concept of low-carbon green transportation is gradually accepted with the enhancement of people's awareness of environmental protection.The mixing temperature of asphalt mixture decreases gradually and hot mixing,warm mixing,cold mixing are three kinds of typical mixing technology.However,there is a lack of research on the long-term aging performance of three kinds of mixtures.Mixing temperature is the main difference among three kinds of mixing technology.The purpose of this study is to investigate the effect of mixing temperature on the long-term aging performance of asphalt.Based on the simulation of three mixing technologies,two kinds of matrix asphalt and three kinds of SBS modified asphalt were treated with short term aging under different temperature and then treated with long term aging under different time.In order to investigate the effect of mixing temperature on the long-term aging performance of different kinds of matrix asphalt and modified asphalt with different SBS content,the conventional properties,rheological properties and functional change of asphalt before and after aging were analyzed.The results show that the effect of mixing temperature on the long-term aging performance of two kinds of matrix asphalt is same but different from the modified asphalt.And the aging law is also affected by SBS content and aging evaluation index.With the penetration,softening point,ductility and 60?G*/sin? as matrix asphalt aging evaluation indexes,aging degree is cold mix asphalt < warm mix asphalt < hot mix asphalt after mixing,but the gap decreases with time and they have the same aging degree when PAV20 h.Meanwhile,the aging degree is always cold mix asphalt < warm mix asphalt < hot mix asphalt when it is expressed with viscosity at 60?.When S and m were used to characterize the low temperature crack resistance,the effect of mixing temperature on the matrix asphalt was not obvious.With the penetration,ductility and dynamic viscosity at 60? as modified asphalt aging evaluation indexes,the result of aging degree is always cold mix asphalt< warm mix asphalt< hot mix asphalt.When G*/sin? at 60? was used as the evaluation index of the aging degree,the aging of the cold mix asphalt was lower than that of the warm mix asphalt,and the gap gradually decreases to zero with the extension of time.The aging degree of cold mix asphalt and warm mix asphalt has been lower than that of hot mix asphalt all through.When the mixing temperature reaches 183?,the aging degree of the asphalt increases obviously and the increase degree of matrix asphalt is higher than that of the modified asphalt.When PAV is less than 15 h,the influence of SBS dosage for residual penetration ratio is not significant.The anti aging ability of SZ-70 is better than that of some of the modified asphalt when aging index indicates the degree of aging.Also,the aging degree of modified asphalt with 4.0%SBS is approximate maximum in the cold mixing and hot mixing process,but in warm mixing process the aging degree of modified asphalt with 4.8%SBS is the highest.When the PAV time is greater than 15 h,the higher the SBS content is,the better the aging resistance of asphalt is with aging index and residual penetration ratio indicating the degree of aging.The temperature sensitivity of the matrix asphalt increases with the advance of asphalt aging degree.On the contrary,the modified asphalt presents the opposite law.The dependence of G"and G' on frequency decreases with the increase of SBS content and aging degree.With the aging time extending,G*/sin? of modified asphalt showed a plateau period,and the lower the mixing temperature is,the later the platform period appeared.? of matrix asphalt decreases linearly with aging time,but the modified asphalt is different.? of modified asphalt decreases with aging time,and then rebound,and the rebound degree becomes significant with the decrease of mixing temperature and the increase of SBS content.The content of carbonyl and sulfoxide of matrix asphalt and modified asphalt increases with aging time,but the trend is different.SBS modifier inhibits the formation of carbonyl to some extent.However,the formation of the sulfoxide mainly depends on the content of sulfur in the asphalt...