Research On The Aging Performance Of Asphalt With Different Composition And Structure Based On Rheological Properties

Asphalt pavement has been widely used in the high-grade highways for its advantages of vibration and noise reduction,wear resistance,and easy maintenance.However,as the service period of the pavement increasing,asphalt will age under the action of heat,ultraviolet light,oxygen,moisture and other environmental factors,resulting in changes in its chemical composition and molecular structure,leading to deterioration of physical and rheological properties.Asphalt is produced by processing crude oil,and the chemical composition and molecular structure of asphalt refined from different crude oils vary greatly,which has a great influence on its physical and rheological properties.However,there is a lack of identical studies on the aging properties of asphalts with different compositions.In this paper,we firstly characterized the composition and structure of asphalts produced by different crude oils and processing using Fourier transform infrared spectroscopy(FT-IR),elemental analysis,nuclear magnetic resonance hydrogen spectroscopy(~1H-NMR)and gel permeation chromatography(GPC),and then tested the temperature sensitivity,high temperature dynamic viscoelasticity,low temperature dynamic viscoelasticity and repetitive creep recovery performance of different asphalts before and after aging.The influence of asphalt composition and structure on its aging performance was explored.Finally,the relationship between composition and structure and asphalt aging performance was established by linear regression analysis and gray correlation analysis.The main results are as follows:(1)The structural characterization of 12 types of asphalts produced from different crude oils using FT-IR,elemental analysis,~1H-NMR and GPC revealed that the hydrogen-to-carbon ratio,molecular weight and the average molecular structures of asphalts differed significantly.The H/C of different asphalts ranged from 1.34 to1.70,the number average molecular weight ranged from 564 to 766,the aromatic carbon ratio ranged from 0.192 to 0.368 and the aromatic ring number ranged from1.332 to 4.241.(2)The composition and structure of asphalt have a great influence on its rheological properties.For temperature sensitivity,asphalts with high molecular weight,high aromatic carbon ratio,high aromatic ring number and low hydrogen carbon ratio have small temperature sensitivity coefficient,that is,viscosity is the least sensitive to temperature change;For low temperature rheological properties,asphalts with low molecular weight,low aromatic carbon rate,low aromatic ring number and high hydrogen carbon ratio have smaller complex modulus,smaller fatigue factor and larger phase angle,showing better anti cracking deformation ability;For high temperature rheological properties,asphalts with high molecular weight,high aromatic carbon rate,high aromatic ring number and low hydrogen carbon ratio have larger complex modulus,larger rutting factor and smaller phase angle,showing better anti rutting deformation ability.(3)The composition and structure of asphalt had a great influence on its rheological properties before and after aging.Asphalts with higher molecular weight,aromatic carbon rate and aromatic ring number,but lower hydrogen carbon(such as QZ70#,NB70#,GZ70#and SL70#)showed better aging resistance after aging with smaller temperature sensitivity change rate,complex modulus ratio,rutting factor ratio,fatigue factor ratio,recovery rate ratio and larger phase angle ratio;while the asphalt with lower molecular weight,aromatic carbon rate and aromatic ring number,and higher hydrogen carbon ratio(such as DY70#,LH70#,HF70#and BH70#)exhibited poor aging performance with larger temperature sensitivity change rate,complex modulus ratio,rutting factor ratio,fatigue factor ratio,recovery rate ratio and smaller phase angle ratio after aging.(4)The linear correlation analysis showed that the correlation between aromatic carbon rate,hydrocarbon ratio,aromatic ring number and molecular weight of asphalt and rheological aging index were good.The aromatic carbon rate,aromatic ring number and molecular weight were negatively correlated with complex modulus ratio,fatigue factor ratio,rutting factor ratio and recovery rate ratio,and positively correlated with phase angle ratio,and the hydrogen carbon ratio was positively correlated with complex modulus ratio,fatigue factor ratio,rutting factor ratio and recovery rate ratio,and negatively correlated with phase angle ratio,which indicated that as the aromatic carbon rate,aromatic ring number and molecular weight increased and the hydrogen carbon ratio decreased,the asphalt could exhibit better anti-aging properties.(5)The gray correlation analysis showed that the aromatic carbon rate,aromatic ring number,molecular weight and hydrogen to carbon ratio all correlated well with the rheological aging index.The influence of hydrogen carbon ratio and molecular weight on rheological aging index was greater than that of aromatic carbon rate and aromatic ring number,and the influence of composition on rheological aging index was in the following order:hydrogen carbon ratio>molecular weight>aromatic carbon rate>aromatic ring number.