Temperature and thermal history dependence of the microstructure in bituminous materials

Nahar, Sayeda; Schmets, A.J.M.; Scarpas, A.; Schitter, Georg

doi:10.1016/j.eurpolymj.2013.03.027

Cited by 65 publications

(52 citation statements)

References 25 publications

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“…Also, undisputable observations of microstructural phenomena in pure maltenes [53] were made. Additionally, by using heating and cooling cycles, it was proven that these structures vanish completely at around 90°C and reemerge when the sample is cooled down [39], similar to a classical crystallization scenario. This is interpreted as being in the same temperature range as the melting points of waxes commonly found in bitumina [39].…”

Section: Discussionmentioning

confidence: 87%

The bitumen microstructure: a fluorescent approach

et al. 2014

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Five bituminous samples were carefully studied by confocal laser scanning microscopy using 488 nm excitation radiation and observing 500-530 nm of emission. The images revealed the microstructure of bitumen. The influence of the admixture of mineral aggregates concerning the microstructure was tested. For the minerals, no significant influence was found. For understanding the origin of fluorescent signals, the samples were separated into asphaltenes and maltenes and analyzed with fluorescence spectroscopy. Although former works have assumed the origin of fluorescent emissions in bitumen to be found in the asphaltene fraction, the asphaltenes produce little to no emissions, but the maltenes exhibit strong fluorescence in the observed spectral region. For deeper insight, fractionation of the bitumina into the SARA fractions by chromatographic column separation was necessary. The fluorescence spectra of these fractions were analyzed and revealed the aromatics and resin phases to be the only components capable of sufficiently intense fluorescent emission. This is a strong argument for a complex internal microstructure consisting of a mantle of aromatics surrounding an inner core.

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Section: Discussionmentioning

confidence: 87%

The bitumen microstructure: a fluorescent approach

et al. 2014

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“…A typical domain phase with a wrinkling along the long axis, most often termed as bee structure or catana phase, is observed to be dispersed over a continuous matrix phase (perpetua phase) [44][45][46][47][48]. The domain phase with wrinkling and the matrix phase are often considered to be the characteristic features of the bitumen microstructure [44,[47][48][49][50]. However, the precise morphology of the microstructure is known to be dependent on the bitumen origin and its thermal history [47].…”

Section: Microstructure From Afmmentioning

confidence: 99%

“…The domain phase with wrinkling and the matrix phase are often considered to be the characteristic features of the bitumen microstructure [44,[47][48][49][50]. However, the precise morphology of the microstructure is known to be dependent on the bitumen origin and its thermal history [47].…”

Section: Microstructure From Afmmentioning

confidence: 99%

Impact of maltene and asphaltene fraction on mechanical behavior and microstructure of bitumen

et al. 2015

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As a widely accepted concept, bitumen consists of four fractions that can be distinguished by their polarity. Highly polar asphaltene micelles are dispersed in a viscous phase of saturates, aromatics and resins (maltene phase). Different concentrations of asphaltenes in the bitumen result in a range of mechanical response properties. In an interdisciplinary study the impact of the maltene phase and asphaltenes on the linear viscoelastic behavior and the microstructure of bitumen were analyzed by creep recovery testing in a DSR and by atomic force microscopy (AFM). Therefore, bitumen was separated into the maltene and asphaltene fractions and artificial bitumen samples with different, pre-defined asphaltene concentrations were produced and investigated. It was found that the artificially produced, precipitated bitumen samples can be regarded as a representative, bitumen-like material in terms of mechanical behavior and microstructure. Asphaltenes play an important role in the typical viscoelastic behavior of bitumen being mainly responsible for stiffness and elasticity. Also, their concentration appears to be correlated to the occurrence and shape of the bee-like inclusions which can be typically observed by AFM.

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“…Thus, it provides a map of domains with different rheological or mechanical properties [22]. As observed in Figure 8, bitumen microstructure is characterised by a two phase system where randomly distributed ellipsoids, often referred to as "bee-shaped" structures, are dispersed in a continuous phase [34]. However, the chemical composition and origin of the observed phases is a -17 -controversial topic and a matter of debate.…”

Section: Chemical Modification and Microstructurementioning

confidence: 99%

“…In this sense, some authors postulate that the bee-structures consist of the most polar fraction of bitumen [22,35] and so they resemble the colloidal model. On the other hand, others authors have attributed the "bee" structures as the result of co-precipitation of non-wax asphalt compounds with crystallizing non-polar waxes [34,36].…”

Section: Chemical Modification and Microstructurementioning

confidence: 99%

Processing of bitumens modified by a bio-oil-derived polyurethane

Cuadri¹,

García‐Morales²,

Navarro³

et al. 2014

Fuel

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Castor oil (CO) functionalized by isocyanate groups (-NCO) is proposed as a novel bio-based reactive polyurethane (PU) for bitumen modification. This work presents a comparative analysis conducted on blends of bitumen and 2 wt.% of a PU prepolymer prepared by NCO-functionalization of castor oil. Four preparation procedures were evaluated, which resulted from the combination of two processing times (1h or 24h, at 90ºC) followed by two different post-treatments (water addition or ambient curing for up to 6 months). It was found that the degree of modification attained after posttreatment depends on the previous processing conditions. Thus, short processing times are required if the binder is further subjected to ambient curing. Instead, the success of the water-addition modification falls on a previous long processing step. As revealed by rheological tests, ambient curing was seen to be by far a more efficient way of modification if compared to direct addition of water, and makes clear that the resulting binder evolves towards a better performance when in service. In that sense, Thin Layer Chromatography tests, Modulated DSC and AFM images demonstrated a more complex microstructure characterized by the presence of a larger content of molecules with higher polarity, size and molecular weight.

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Temperature and thermal history dependence of the microstructure in bituminous materials

Cited by 65 publications

References 25 publications

The bitumen microstructure: a fluorescent approach

The bitumen microstructure: a fluorescent approach

Impact of maltene and asphaltene fraction on mechanical behavior and microstructure of bitumen

Processing of bitumens modified by a bio-oil-derived polyurethane

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