Effects of Different Aging Methods on Chemical and Rheological Properties of Bitumen

Abstract

Bitumen undergoes ageing, which leads to changes in its chemical and rheological properties, thus becoming harder and more brittle in time. This study aims to compare the effects of different laboratory ageing methods on chemistry and rheology of three bitumen types, i.e. a Pen 40/60, a Pen 70/100 and a polymer modified bitumen (PmB). Four ageing protocols were applied: ageing at room temperature, oven ageing, the Pressure Ageing Vessel (PAV), and the Rolling Thin Film Oven Test (RTFOT) combined with PAV ageing. The effects of temperature, pressure, and ageing time were studied using dynamic shear tests and infrared spectroscopy. The results highlight the relationship between chemistry and rheology of bitumen.Bitumen hardening, which was revealed by an increase in complex modulus and a decrease in phase angle, was reflected in the growth of specific chemical functional groups. Among all materials, soft bitumen showed the greater tendency to oxidize. Different behaviour was observed for PmB that presented the highest resistance against oxidation among the studied bitumens, even though the reaction with oxygen caused the deterioration of the added polymer modifiers.

Rheological, fatigue and relaxation properties of aged bitumen

“…Nevertheless, temperature was found to be the most influential parameter for ageing, probably because the ageing rate coefficient increases exponentially with temperature based on the Arrhenius equation. Detail on the effect of the ageing parameters on the rheology of the studied bitumen type are discussed in previous studies (Jing et al 2018, Tarsi et al 2018. Black diagrams, Figure 2, were plotted to present the rheological changes of bitumen with ageing.…”

Effect of laboratory aging on chemistry and rheology of crumb rubber modified bitumen

“…Carbonyl compounds and sulfoxides are commonly formed during the chemical transformations caused by oxidative aging. Therefore, to quantitatively analyze the changes of specific functional groups due to the aging effects, the peak areas under the specific band were measured from valley to valley at specifically selected wavenumbers of the obtained spectrum [24].Two aging related indices, the carbonyl index (I C¼O ) and ) were also calculated to monitor the evolution of chemical constituents of binder during aging [8].…”

“…The sum of carbonyl index and sulfoxide index was used as the combined chemical aging index of bitumen after aging [36]. It is noteworthy that although aromaticity index of a binder is closely related to its mechanical properties [37], the relationship between aromaticity level and aging state is not well-defined as the carbonyl or sulfoxide index [8]. Therefore, the correlation was not done between aromaticity and mechanical parameters.…”

“…The changes of bitumen chemistry after aging significantly influence the physical and rheological characteristics of bitumen. Aging causes stiffening of bitumen with reduced molecular flow, which can be verified by the increase in viscosity and complex modulus and decrease in phase angle [7,8]. The stiffening effect increases the permanent deformation resistance, but reduces the relaxation capacity under environmental and traffic loadings resulting in performance deterioration of asphalt pavements [9,10].…”

Rheological, spectroscopic and microscopic assessment of asphalt binder ageing

“…Many researchers have investigated the effect of ageing on rheological and chemical properties of asphalt binders (e.g. Feng et al, 2013;Leiva-Villacorta et al, 2014;Lu & Isacsson, 2002;Molenaar et al, 2010;Osmari et al, 2017;Osmari et al, 2018;Petersen, 2009;Qin et al, 2014;Takahashi et al, 2019;Tarsi et al, 2018;Wang et al, 2015;Zhang et al, 2018). A review of laboratory protocols to test asphalt binder ageing can be found in Wistuba and Renken (2011).…”