Reversible Aging in Asphalt Binders

Abstract

X-ray diffraction, optical microscopy, and mass spectrometry techniques were used in an attempt to clarify the morphological and chemical features that are responsible for reversible aging processes that occur in asphalt binders during conditioning at low temperatures. The reversible aging term is used in this paper to capture all reversible processes (i.e., wax crystallization, free volume collapse, asphaltene aggregation, etc.) that lead to a reduction in low-temperature rheological and fracture performance. Crystalline content and asphaltene aggregate size at ambient temperatures, as measured by X-ray diffraction on thin asphalt films, are identified as two factors that correlate reasonably well with the reversible aging tendency at low temperatures. A coarse and unstable colloidal state for the asphaltene fraction is also identified as an important contributor to reversible aging. It was found that the saturates fraction has a particularly significant role in the aging process, with those asphalts containing higher amounts of linear paraffin losing more in terms of rheological performance. This important phenomenon is responsible for significant fracture distress in asphalt pavements in northern climates and therefore deserves further investigation. Some of the air-blown asphalts investigated in this study were found to show a high crystalline content and a coarse phase morphology and concurrent tendency for reversible aging during cold conditioning. This may be due to the crude source(s) employed, the chemistry of the air-blowing process, or resulting phase changes. Other air-blown binders did not show these features while they were still susceptible to reversible aging. Hence, the reason for this behavior appears to be due to multiple processes which are at present only poorly understood.

Characterization of physical aging by time-resolved rheometry: fundamentals and application to bituminous binders

“…In particular, the effects of temperature, crystallinity and polymer modification are studied. The results of these analyses are of great importance especially to the asphalt paving industry as the physical aging of bituminous binders has a major impact on the durability of asphalt pavements (Iliuta et al 2004b, a;Soenen et al 2004;Yee et al 2006;Zhao and Hesp 2006;Hesp et al 2007Hesp et al , 2009aEvans et al 2011;Bahia et al 2012;Paul Togunde and Hesp 2012;Freeston et al 2015).…”

Modeling X-ray Line Shapes from Asphaltenes

“…The asphaltene samples were obtained from Canadian crude oil and asphalt by using solvent separation methods [5]. They were then coated onto glass slide holders by heating to 150°C for 10 minutes in a drying oven followed by cooling to ambient (25°C) temperature.…”

“…The X-ray diffraction (XRD) system used was a Rigaku Dmax 2200V-PC and Jade TM software (version 6.1) [4][5]. XRD was performed by using Cu-K-α radiation operating at 40 KV and 40 mA, scan rate of 0.001° 2θ per second and detector count time of 5 seconds/step.…”

Evaluation of bitumen fractional composition depending on the crude oil type and production technology

“…Their elemental analysis is stable from one bitumen to the other with H/C ratio between 0.98 and 1.56. Their solubility parameter ranges between 17.6 and 21.7 MPa 0.5 and their density at 20 °C is close to 1.15 g/cm 3 [ [4][5][6][7][8][9][10][11][12][13][14].…”