| With the rapid development of the infrastructure construction of transportation around China,asphalt materials have been widely used in various expressway projects.Among all the main factors which affect the quality of tar road,asphalt binders has always been considered as the most important one.This study was performed with the implementation of Fengping project.It is a reconstruction project from Fengxiang intersection of the national highway G312 near the provincial boundary between Shaanxi and Gansu to East Pingliang at the Village of Caowan.In the study,infrared spectrum technique was used to perform the analysis of functional groups in commonly used products of asphalt available in Gansu Province.The investigation on the fingerprint identification of base material of asphalt was carried out.The amount of SBS modifier in SBS modified asphalt products was determined.Furthermore,infrared spectroscopy technique was used to reveal the aging mechanism of asphalt.The following results was obtained:(1)We studied an asphalt product of Karamay Petrol-Chemical Industry Company(c-product).And a unique absorption peak in the infrared fingerprint region distinguished the asphalt product from the others.Two absorption peaks of the asphalt products from Xi’an branch company of Sinopec(x-product)and the Tahe company(t-product)are significantly different from the other products.The above two peaks can be ascribed to the characteristic peaks of butadiene group and polystyrene group of SBR or SBS.So it can be concluded that SBR or SBS was added during the modification process.Meanwhile,absorption for light components was also detected,which can be used to distinguish x-and t-products from the other ones available in the market.All the products of 9 brands on sale in Gansu market can be classified into 4 categories.(2)It was observed that the characteristic absorption peak changes as the content of modifier changes.The shape of two peaks are significantly obvious.According to the relationship between the ratio of the integral areas of the two peaks and the dosage,the standard curve was plotted.Therefore,it could be used to determine the amount of modifier added to the modified asphalt.(3)The aging degree of both base asphalt and modified asphalt was characterized by carbonyl group at 1700 cm-1 and sulfoxide at 1033 cm-1.Different aging methods of different asphalt brands have a different impact on the aging properties of asphalt..After the aging of the x-product-#90,the carbonyl and sulfoxide groups changed most obviously.SK-#90 asphalt followed,and the c-product-#90 did not change significantly.The result was consistent with their actual performance after aging.It is indicated that the degree of aging of asphalt can be measured by the change in the absorption peak of the group.It was found that the carbonyl absorption peak continued to increase as the aging temperatUre and aging time increase.It indicates that the weak polar molecules,such as ketones and carboxylic acids,kept reacting with oxygen in the asphalt during the aging process.When temperature rises,the oxidation of the asphalt can be accelerated.The reaction rate of oxygen and polar molecules become faster due to the increase of temperature.In addition,the temperature rise causes the associates of molecules to be cracked,further promoting the combination of these components with oxygen and increasing the oxidation component.(4)The change of sulfoxide groups during asphalt aging is very unique.The change is obvious at low temperature.And a process of decomposition followed the initial formation process.(5)Infrared spectroscopy technique was used to study different types of asphalt binders during the implementation of the Fengping project.The study show that the results from the infrared spectroscopy technique for the performance measurement of asphalt binders are basically consistent with the actual results.It paves the way for more applications of infrared spectroscopy in testing asphalt binder. |
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