The steric hardening and structuring of paraffinic hydrocarbons in bitumen

Frolov, I. N.; Bashkirceva, N. Y.; Зиганшин, Марат А.; Okhotnikova, E. S.; Firsin, A. A.

doi:10.1080/10916466.2016.1221962

Cited by 26 publications

(10 citation statements)

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“…The hardening undergone by the asphalt binder can be reversible or irreversible. The reversible hardening (physical aging or steric aging) is caused by the reorganization of asphalt binder molecules and/or wax crystallization, which can be reversed by the warming up of the asphalt binder [ 8 , 9 , 10 , 11 ]. The irreversible aging (chemical aging) is caused by different processes such as oxidation, polymerization, evaporation of light components, and exudation of oil components from asphalt binder into a mineral aggregate [ 11 , 12 ].…”

Section: Introductionmentioning

confidence: 99%

Effect of Thermal and Oxidative Aging on Asphalt Binders Rheology and Chemical Composition

et al. 2020

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Aging of asphalt binders is one of the main causes of its hardening, which negatively affects the cracking and fatigue resistance of asphalt binders. Understanding asphalt aging is crucial to improve the durability of asphalt pavements. In this regard, this study aims at understanding and differentiating the effect of temperature and oxygen uptake on the aging mechanisms of unmodified asphalt binders. For that, four laboratory aging procedures were employed. The two standardized procedures, rolling thin-film oven test (RTFOT) and pressure aging vessel (PAV), were considered to simulate the short-term and long-term aging of the asphalt binders, respectively. In addition, two thin-film aging test procedures, the nitrogen atmosphere oven aging test (NAAT) and ambient atmosphere oven aging test (OAAT) were employed to assess the effect of thermal and oxidative aging on unmodified asphalt binder properties. The NAAT procedure is based on the principle that the inert gas minimizes the oxidative aging. The rheological and chemical characterization showed that the high temperatures considered during the NAAT procedure did not change the properties of the unmodified asphalt binders. Therefore, it can be hypothesized that no significant thermal and oxidative aging was observed during NAAT aging procedure for the considered binders and that oxidative aging is the main cause for the hardening.

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Section: Introductionmentioning

confidence: 99%

Effect of Thermal and Oxidative Aging on Asphalt Binders Rheology and Chemical Composition

et al. 2020

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“…However, cold crystallization arises at the glass temperature region . Additionally, because the glass transition event is absent on the reversing heating curves at the exotherm temperature range, as in Figure (the glass transition can be identified only on reversing TMDSC curves), Frolov et al concluded in earlier work that there is a recrystallization exotherm.…”

Section: Resultsmentioning

confidence: 97%

“…Differences between the bitumen waxes are also reflected in their thermal analyses. ,, In general, waxes with a predominance of n -alkanes melt and crystallize within a narrower and higher temperature range. The sharpness of the wax crystallization/melting peaks decreases with an increase of iso- and cycloalkanes and aromatics. , Therefore, it can be suggested that multiple peaks can be due to the overlapping dissolution events of two different types of wax crystals. , If bitumen has two distinct crystalline wax populations, each should have its own constant characteristic temperature of dissolution (a range of temperatures) that is independent of the annealing temperature. The dissolution temperature is an internal inherent property of the system.…”

Section: Resultsmentioning

confidence: 99%

“…Masson et al , approached the explanation of the multipeak endotherm by superimposing the cold crystallization exothermic peak and the endothermic background. Frolov et al supposed the formation of the double-peak profile by overlapping the recrystallization exotherm and the dissolution endotherm. Lesueur et al concluded that a full description of the double-peak endotherm remains to be published.…”

Section: Introductionmentioning

confidence: 99%

“…In their works, Masson et al , and Frolov et al used temperature modulated DSC (TMDSC). This method allows the signal of the total heat flow (equivalent to that of conventional DSC) to be deconvoluted into two components.…”

Section: Introductionmentioning

confidence: 99%

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Interpretation of Double-Peak Endotherm on DSC Heating Curves of Bitumen

et al. 2020

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Since the late 1960s, differential scanning calorimetry (DSC) has been used to characterize petroleum bitumen, in particular, for the determination of the crystallized fraction (CF) content. This procedure is based on the construction of a baseline after identifying the CF dissolution endotherm on the heating curve. However, many bitumens commonly exhibit double-peak endotherms during a DSC heating scan. In this case, the task of constructing the corresponding baseline does not have a unique solution because the interpretation of the heat flow profile is ambiguous. Several interpretations have been proposed earlier to explain the origins of the double-peak endotherm. However, the double-peak endotherm is currently still not fully understood, and a comprehensive consensus has not been achieved. If the determination of the baseline location is incorrect, the CF content can be over- or underestimated by 20–30%. In the current work, double-peak endotherm behavior was investigated by temperature modulation DSC. All of the earlier explanations were critically considered. The origin of the double-peak endotherm was discussed in detail, and a probable descriptive model for the formation of the double-peak endotherm was suggested. The endotherm pattern is assumed to be governed by three overlapping thermal events: a broad endothermic background and a twin “recrystallization exotherm–dissolution endotherm” pair. The onset of the recrystallization exotherm and the intensity of both events depend on the annealing temperature and time. The study promotes a better understanding of the relationship between the thermal effects on the DSC curves and the structural changes of bitumen. A correct interpretation of the double-peak endotherm can provide a more exact determination of the CF content in bitumen.

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