Identification Of Asphalt Aging Gene And Prediction Research Of Aging Law Based On Omics Technology

Asphalt as a binder is widely used in pavement engineering.However,the aging of asphalt in the process of use is prone to occur,which seriously affects the performance and durability of asphalt pavement.Therefore,it is of great significance to study the aging process of asphalt and to understand the aging mechanism and law of asphalt.At present,the research on asphalt aging is mainly based on the characterization of physical properties of specific asphalt samples.It is generally believed that the physical properties of different asphalts are basically the same after aging,but the anti-aging properties and durability of different asphalts vary greatly.The macro-physical properties and corresponding changes of asphalt are the reflections of complex chemical composition,molecular structure and changes,and their interactions.However,the molecular mechanism and aging mechanism of asphalt aging are still unclear.Five different types of AH-70 asphalt were selected for short-term aging and long-term aging tests,then 30 asphalt samples were obtained.The effects of aging time on physical properties of asphalt were investigated.The composition and structure of asphalt were characterized by four-component analysis,elemental analysis,infrared analysis and thermo gravimetric analysis.The main groups affecting asphalt aging were identified.The infrared fingerprints of asphalt were analyzed by ATR-FTIR and Omics technology.Based on partial least squares method,the prediction models of asphalt physical properties and four components were established.Five different types of AH-70 asphalt were selected as samples,followed by the thin film oven aging test(TFOT)and pressure aging test(PAV)to simulate the short-term aging and long-term aging(PAV5h,PAV10 h,PAV15h and PAV20h),respectively.Then 30 asphalt samples with different aging degrees were obtained.The effects of different aging time on penetration,softening point,ductility and viscosity were analyzed.By calculation,the penetration ratio,softening point increment,ductility ratio and viscosity ratio were introduced as indexes to evaluate the aging resistance of asphalt.The results show that with the increase of aging time,the physical properties of different asphalts show similar changes,i.e.,penetration decreases,softening point increases,ductility decreases and viscosity increases.According to the aging resistance indexes,the aging resistance of asphalts is evaluated comprehensively,and it is found that the aging resistance of KL asphalt is the best,followed by SL and SZ asphalts,QL and LH asphalts have the worst aging resistance.In order to reveal the aging mechanism of asphalts,the composition and structure of asphalts were characterized by four-component analysis,elemental analysis,infrared analysis and thermogravimetric analysis.The results show that the chemical composition and molecular structure of aged asphalt have changed greatly.In terms of component composition,the transitions from aromatics to resins,and then to asphaltenes have taken place.In terms of element composition,the content of O increases and H/C decreases after aging.The aging of asphalt increases the internal aromatic ring substances,and the condensation degree of aromatic rings increases,resulting in more complex ring structure and larger molecular weight.From the point of view of functional group structure,with the deepening of aging degree,the content of carbonyl and sulfoxide oxygen-containing polar groups increased,indicating that oxidation reaction occurred in the aging process of asphalt.The results of thermo gravimetric analysis show that with the increase of aging degree,the absolute value of the maximum value of the residual mass ratio and the loss rate of thermo gravimetry shows a decreasing trend.With the deepening of aging degree,the light components in asphalt,under the combined action of temperature and pressure,are transformed into more stable resins and asphaltenes,which is consistent with the increase of resins and asphaltenes content in the results of four-component analysis.Furthermore,the key chemical compositions such as the content of four components,the content of oxygen elements and the key molecular structures such as oxygen-containing polar functional groups(carbonyl and sulfoxide)are defined as "aging genes" of base asphalt.Based on ATR-FTIR and Omics technology,the asphalt fingerprints were identified,and the similarity analysis,cluster analysis,principal component analysis and discriminant analysis were carried out.The results show that the fingerprints information of asphalt is inherited from the crude oil which produces asphalt.Aging only changes a small part of the fingerprints characteristics of asphalt.Aged asphalts from the same oil source still have more similar chemical compositions than those from other oil sources.According to the principal component analysis,the aging degree of asphalt can be preliminarily determined.The discriminant analysis is used to establish a method for determining the asphalt oil source.The results of cross-validation classification show that the discriminant function is stable and the total accuracy is 100 %。It can be used to determine the oil source of unknown asphalt samples.On the basis of ATR-FTIR spectroscopy and Omics technology,the prediction models of penetration,softening point,ductility,viscosity and four components of asphalt are constructed and evaluated.The results show that there is a high correlation between the infrared spectrum of asphalt and its physical properties and four components.The prediction of asphalt indexes before and after aging can be achieved by combining ATR-FTIR technology with Omics technology,and the models can be effectively simplified and the prediction accuracy can be improved by extracting characteristic wavelength.