Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Comparison between thermal, rheological and failure properties for the performance grading of asphalt cements
Highlights Thermal properties fail to correlate with asphalt cement rheological and failure properties. Asphalt cement ductility correlates with approximate critical crack tip opening displacement (CTOD). Phase angles are able to differentiate asphalt cements with a high degree of precision and sensitivity.
Abstract Thermal, rheological and failure properties of nine extracted and recovered asphalt cements were investigated to predict cracking susceptibility. Glass transition temperatures, non-isothermal Ozawa crystallization constants and binder fragilities were determined but found to lack a strong correlation with established performance indicators. All binders exhibited thermorheologically simple behavior and master curves for complex modulus and phase angle were readily constructed by applying the time-temperature superposition (TTS) principle. Failure properties of the binders were determined using ductility and double-edge-notched tension (DENT) tests. It was found that the ductility and approximate critical crack tip opening displacement (CTOD) are correlated, although the latter provides more reasonable (lower) values of strain tolerance. The Williams-Landel-Ferry (WLF) equation described the shift factors in dynamic shear, and the WLF constants C1 and C2 correlate reasonably well with ductility and CTOD. It was found that the phase angle was sensitive to asphalt cement quality, with poor performing binders showing a limiting phase angle temperature, T(δ = 45°), nearly 25 °C higher than those of superior performing materials. This investigation demonstrates that recovered binders can be prematurely hardened, likely due to overheating during production or the incorrect use of reclaimed asphalt. As this problem is not recognized when testing material from the asphalt cement supply tank, it is recommended to test extracted and recovered binder from the loose hot mix asphalt. This will assure that the material as placed actually meets performance requirements for the local climate.
Comparison between thermal, rheological and failure properties for the performance grading of asphalt cements
Highlights Thermal properties fail to correlate with asphalt cement rheological and failure properties. Asphalt cement ductility correlates with approximate critical crack tip opening displacement (CTOD). Phase angles are able to differentiate asphalt cements with a high degree of precision and sensitivity.
Abstract Thermal, rheological and failure properties of nine extracted and recovered asphalt cements were investigated to predict cracking susceptibility. Glass transition temperatures, non-isothermal Ozawa crystallization constants and binder fragilities were determined but found to lack a strong correlation with established performance indicators. All binders exhibited thermorheologically simple behavior and master curves for complex modulus and phase angle were readily constructed by applying the time-temperature superposition (TTS) principle. Failure properties of the binders were determined using ductility and double-edge-notched tension (DENT) tests. It was found that the ductility and approximate critical crack tip opening displacement (CTOD) are correlated, although the latter provides more reasonable (lower) values of strain tolerance. The Williams-Landel-Ferry (WLF) equation described the shift factors in dynamic shear, and the WLF constants C1 and C2 correlate reasonably well with ductility and CTOD. It was found that the phase angle was sensitive to asphalt cement quality, with poor performing binders showing a limiting phase angle temperature, T(δ = 45°), nearly 25 °C higher than those of superior performing materials. This investigation demonstrates that recovered binders can be prematurely hardened, likely due to overheating during production or the incorrect use of reclaimed asphalt. As this problem is not recognized when testing material from the asphalt cement supply tank, it is recommended to test extracted and recovered binder from the loose hot mix asphalt. This will assure that the material as placed actually meets performance requirements for the local climate.
Comparison between thermal, rheological and failure properties for the performance grading of asphalt cements
Khan, Ahmad Nawaz (Autor:in) / Hesp, Simon A.M. (Autor:in)
Construction and Building Materials ; 220 ; 196-205
30.05.2019
10 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
AASHTO , American Association of State Highway and Transportation Officials , BBR , bending beam rheometer , CTOD , critical crack tip opening displacement , DCM , dichloromethylene , DENT , double-edge-notched tension , DSR , dynamic shear rheometer , EBBR , extended bending beam rheometer , MDSC , modulated differential scanning calorimetry , MTO , Ontario Ministry of Transportation , PAV , pressure aging vessel , SHRP , Strategic Highway Research Program , TTS , time-temperature superposition , WLF , Williams-Landel-Ferry , Asphalt cement , Performance grading , Glass transition , Fragility , Ductility , Phase angle
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