Abstract
The recovery property of asphalt binders plays an important role in the performance and service life of asphalt pavements. Since the internal stress is the driving force for the recovery of asphalt binders, the accurate measurement of the internal stress is full of significance. Based on this rationale, this paper aims to measure the internal stress of asphalt binders using a creep and step-loading recovery (CSR) test and characterizing the recovery behaviors by the internal stress. One base asphalt binder and one styrene–butadiene–styrene (SBS)-modified binder are selected in this study. The key elements of the CSR test are carefully designed and its accuracy is verified in three aspects, including the loading conditions, the effect of disturbance by step-loads, and accuracy of measured internal stress. Then, a kinetics-based recovery model is proposed to evaluate and predict the recovery properties of asphalt binders from its causal relationship. The constant-rate recovery activation energy indicates a major difference with nondestructive and destructive loading conditions, while the fast-rate recovery activation energy keeps almost constant regardless of the loading conditions. After that, the healing activation energy is calculated by using the kinetics-based recovery model and the results indicate that SBS modified asphalt binder shows better healing abilities than a base binder.
Highlights
Rutting, or permanent deformation is one of the common distresses in asphalt pavements due to the permanent deformation accumulation caused by traffic loads, which has a negative influence on the performance and service life of asphalt pavements
This paper aims to measure the internal stress of asphalt binders using the creep and step-loading recovery (CSR) test and characterize the recovery properties of asphalt binders based on the cause-and-effect relationship
After the verification of the CSR for asphalt binders, the step aims at developing a to evaluate and predict the recovery properties of asphalt binders based on the internal stress
Summary
Permanent deformation is one of the common distresses in asphalt pavements due to the permanent deformation accumulation caused by traffic loads, which has a negative influence on the performance and service life of asphalt pavements. There are many factors influencing the resistance to rutting in asphalt mixtures such as binder type, air void content, and bonding stress between aggregate and binder [4]. Among these factors, asphalt binder plays a key role in the performance of asphalt pavements on both the loading and recovery phase, while much less attention is paid to the recovery phase compared with the loading phase, especially for the study of recovery properties in asphalt binders [5]. Understanding the recovery performance of asphalt binders involves understanding its major impact on the performance of the binder itself, and on the asphalt mixtures and pavements, since the binder plays an important role for them as Materials 2020, 13, 920; doi:10.3390/ma13040920 www.mdpi.com/journal/materials
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