Study On The Ageing And Modification Of Paving Asphalt

The vacuum residue was dewaxed by thermal treatment to form the basic asphalt-YH. YH, TH and SH asphalts were taken as testing samples to ivestigate their group fractions and chemical\physical properties. The changes of special functional group and molecular structure of TH and SH asphalts during thermal aging were investigated by a series of analysises, such as elemental analysis, 1H-NMR and XPS. On the basis of above studies, the aging mechanism of asphalt was preliminary studied. The performance of the asphalt was markedly improved by the effective addition of SBS, especially its anti-aging property.The trend of the group fractions was, when asphalt aged, saturates essentially constant, aromatics and resins decreased, whereas asphaltene increased evidently. Meanwhile, the results about properties were as follows: penetration decreased in term of index, softening point increased linearly, lower ductility and colloid instable index increased. The results showed that the aging of paving asphalt was attributed to first order reaction.The molecular structural change in aging proved that, the composition and structure of paving asphalt had large influence on the aging performance of paving asphalt, the structural discontinuity of asphalt components led to the poor of the aging resistant performance of asphalt. The condensation reaction of aromatic ring was occurred. Functional groups such as carbonyl and sulfoxide formed during aging of asphalt. The aging reaction was on radical reaction mechanism.The effect of the modifier and stabilizer quantity on the properties of modified asphalt was analyzed. The optimal dosage of modifier was 4.0%-5.0% and that of stabilizer was 0.15%-0.25%. A comprehensive evaluation of performance and composition was made in this thesis. It was found that the change of the group fractions due to modifier dosage, the stabilizer improved miscible stability of SBS modified asphalt.