Research On Quality Control Method Of Matrix Asphalt Based On Aging Characteristics

As a binder,asphalt is widely used in asphalt pavement engineering.Asphalt quality directly affects the quality of asphalt pavement and its service level and service life.At present,the quality control method of matrix asphalt is mainly controlled from macroscopic physical indicators.The test period is long and the efficiency is low;and it is difficult to solve the adulteration phenomenon of fisheye mixed beads existing in the asphalt supply market,such as using domestic asphalt as imported asphalt,or using mixed blended asphalt to replace the use of a certain brand of base asphalt,the use of weakly modified asphalt counterfeit base asphalt and many other issues.This has brought many hidden dangers to the construction quality and safety of asphalt pavement;it has seriously affected the durability of asphalt pavement,caused early damage to asphalt pavement and increased the maintenance cost in the later period.Therefore,it is particularly important to develop a matrix asphalt quality control method based on infrared spectrum.In this paper,two different domestic AH-70 asphalts were selected,and 28 asphalt samples with different degrees of aging were obtained through short-term aging tests?TFOT?and long-term aging tests?PAV?at different times.By analyzing traditional indexes and rheological performance indexes,the performance decay law of matrix asphalt during the aging process is discussed.The results show that as the aging time increases,the softening point increases and the penetration,ductility,and phase angle decrease;the complex shear modulus,rutting factor,and fatigue factor of each test temperature increase with the PAV aging time It becomes larger,but it tends to decrease first and then increase as the aging time of TFOT increases.Atomic force microscopy and infrared spectroscopy were used to study the changes in the microscopic characteristics of matrix asphalt during the aging process,the results show that as the aging time increases,the microscopic morphology of asphalt changes significantly,and the size of the"peak structure"of the asphalt changes from small to large,and the number of large peaks increases.The intensity of the base characteristic peak increases,and the carbonyl index and sulfoxide index increase.Based on the combination of infrared spectroscopy and statistical technology,similarity analysis,principal component analysis and gray entropy correlation analysis were used to reveal the composition-structure relationship during asphalt aging,and the aging gene characteristics of matrix asphalt were extracted.Studies have shown that aging only changes the content of oxygen-containing functional groups such as carbonyl and sulfoxide groups.This change is a small part of asphalt.The chemical composition of asphalt samples of the same brand with a certain degree of aging is higher than that of asphalt samples of different brands;based on the OMNIC software,the similarity between the infrared spectroscopy of asphalt with a specific degree of aging is calculated by the angle cosine method,When the first similarity is greater than 99.85%,the quality of asphalt can be determined.Principal component analysis revealed the characteristic peaks of asphalt aging genes as 3310cm^-1,1700cm^-1 and1030cm^-1.The gray entropy correlation method was used to analyze the degree of influence of aging genes on the macro index of asphalt.The results showed that the types of aging genes that had the greatest impact on the macro index were influenced by the asphalt brand and aging methods.The infrared spectroscopy analysis combined with multiple regression method was used to construct the prediction model of asphalt penetration,softening point,complex shear modulus,phase angle,rutting factor and fatigue factor.and using F-check to carry out significance check on the prediction model.Based on the study of the relationship between the macroscopic properties of matrix asphalt and the characteristics of aging genes,a quality control method for matrix asphalt based on aging characteristics is proposed:for the matrix asphalt to be tested,the quality of the matrix asphalt is first identified by the first similarity,and then the corresponding macroscopic performance index prediction model is called to determine the aging degree,high and low temperature performance,fatigue performance,etc.of the asphalt and the"future"Precise prediction of indicators,and then achieve the purpose of controlling the quality of matrix asphalt.