Application Of Nuclear Magnetic Resonance Technology In Asphalt Performance Testing

In the course of studying asphalt performance,scholars use a variety of microscopic techniques.Low Field Nuclear Magnetic Resonance(LF-NMR)technology is gradually used in the field of asphalt binder due to its advantages of fast,accurate and non-destructive properties.And has outstanding performance in the performance research of asphalt binder and mixtures.This topic used LF-NMR technology to study the performance characteristics of asphalt binder and mixtures.Discussed the regularity between transverse relaxation time T2,normalized peak area(NPA)and test variables(The type of modifiers,the amount of modifiers and the degree of aged).Established a linear relationship between the rheological properties and NPA of binders.In this study,Shell 70#asphalt was used as the virgin asphalt binder.The asphalt binder was modified with different types and amounts of modifiers(styrene-butadiene-styrene block copolymer,SBS and crumb rubber modifier,CRM).The modified binders were subjected to laboratory aging(rolling thin film oven test,RTFOT and pressure aging vessel,PAV).In terms of mixtures,basalt was used as coarse aggregate and gradation was AC-13.Then used virgin asphalt binder,and its content was 4.92%.The LF-NMR test was performed on the asphalt binders and mixtures.The test temperature was 60℃,and the samples were kept in the equipment hole for 10 minutes.At the same time,in order to verify the feasibility and reliability of LF-NMR for testing asphalt binder performance,the basic performance tests and high temperature rheological performance test were carried out on asphalt binders.The results showed that:(1)On the Amplitude-Time curve,when T2<2 ms,the main peak of each asphalt binder was an"M"relaxation peak;When T2>2 ms,there was no relaxation peak in the virgin asphalt samples and its RTFOT residue.However,relaxation peaks appeared in other asphalt samples.(2)Under the same dosage,the NPA of RTFOT residues were smaller than those of virgin asphalt binder.The NPA of the PAV residues were larger than those of RTFOT residues.(3)With the increased of modifier contents,the NPA of the virgin asphalt binder and its RTFOT residues decreased,and the NPA of PAV residues increased.(4)For a virgin asphalt binder and RTFOT residues,their G~*/sinδwere inversely proportional to their NPA.(5)The relaxation peak shapes of asphalt mixtures were a single,discontinuous peak,which were different from asphalt binders.With the increased of SBS contents,the NPA of the asphalt mixtures gradually increased.(6)The addition of SBS or CRM modifiers reduced the penetration(25°C),increased the softening point,ductility(10°C)and the rotational viscosity at 135°C,and improved the high temperature performance of asphalt binders.