| Asphalt aging leads to deterioration in terms of the pavement performance, which becomes an important factors that affect the durability of asphalt pavement. The modern testing technology, such as Fourier transform infrared spectroscopy experiment(FTIR), thermal analysis(DSC, TG) and mass spectrometry test(MS), are used to study the properties of asphalt binder before and after aging. Analyze the relation between microstructure and macroscopic pavement performance, so that it can reveal the thermal aging mechanism of asphalt binder and provide a theoretical basis for improving the anti-aging properties of asphalt.Asphalt binder samples in three states are prepared of un-aged, short-term aging and long-term aging. The related tests, such as dynamic shear rheological experiments(DSR), dynamic frequency test, Fourier transform infrared spectroscopy experiment, ther mal analysis and mass spectrometry test are carried out..The analyze test data qualitatively and quantitatively by referring to vibration frequency of organic compounds group is analyzed. Compare the characterisytics of of five un-aged asphalt and asphalt before and after aging. According to changes of functional groups in the map, modified mechanism of natural bitumen and the changes of the molecule structure can be presumed during the aging process qualitatively; Compare the changes of the carbonyl index(CI), sulfoxide index(SI), methyl index(MI), the absorbance(fa) and other parameters, then the degree of aging and the conversions of the corresponding functional groups or components are determined, and the thermal aging mechanism of asphalt binder is revealed. Deal with experimental data by DSC, TG and MS before and after aging, comprehensive the location of endothermic peak, mass loss rate and intensity of ion current. The high temperature stability can be known and it can be observed, which is coherent with previous conclusion in infrared spectroscopic analysis.The test results demonstrate that asphalt aging supports the free radical reaction mechanism. This process involves oxidative dehydrogenation reaction with light component volatility that is responsible for short-term aging. However long-term aging is mainly oxygen scavenging reaction, which generating a lot of carbanyl group and sulfoxide group, thus accelerating the aging; After aging, a higher softening point, a better complex shear modulus and a bigger anti-rutting factor are achieved, but the penetration and phase angle become smaller, which means that the high temperature stability of asphalt binder has been greatly improved, the increase in adhesion improves the water resistance of asphalt binder, temperature sensitivity and the low temperature cracking resistance of asphalt binder drops a little bit. Furthermore, residual penetration ratio can be used as an indicator when aging evaluation is conducted, and the changes of molecular structure during aging can provide chemical basis for the study of the resistance against aging.The modern testing technology can reach the same conclusion about high temperature stability and adhesion behavior stability before and after aging. It can also be favourable to determine the optimum content of modifier agent. The technology can be used to study asphalt binder. |
PDF Full Text Request