Effect of introduction of furfural on asphalt binder ageing characteristics

Asphalt oxidative ageing and excessive hardening are known causes of premature pavement cracking. Asphalt ageing occurs mainly due to the oxidation of certain functional groups in asphalt as well as the loss of the maltene phase disturbing colloidal stability and increasing micellisation concentration. This in turn can cause large non-soluble asphaltene aggregates which are typically suspended in the maltene solution and are stabilised by resin molecules to flocculate. Flocculation can cause the asphalt to become stiffer and more brittle. It should be noted that excessive hardening and brittleness of asphalt caused by oxidation during pavement production and service life increase the susceptibility of asphalt pavements to cracking. Therefore, reducing the extent of asphalt oxidation could increase pavement service life. Therefore, it is imperative to reduce/delay asphalt oxidation in asphalt binder. There have been several studies on delaying asphalt oxidation by introducing modifiers and anti-ageing additives. Furfural, an organic compound derived from a variety of agricultural by-products, has been shown to be a promising modifier for petroleum asphalt binders used in asphalt pavement. Accordingly, this paper investigates the effect of introducing furfural as an antioxidant for asphalt by evaluating the extent of oxidation ageing in asphalt specimens modified by 1%, 2% and 5% furfural. To do so, furfural was introduced to asphalt and the level of change in physiochemical and rheological properties of asphalt after specimens were exposed to short- and long-term ageing was examined. Accordingly, performance characteristics of the base asphalt were compared with those of furfural-modified asphalts using a rotational viscometer, Fourier transform infrared spectroscopy and a dynamic shear rheometer to evaluate the rheological properties of asphalt modified with furfural at different percentages. The study results showed that the addition of furfural helped reduce the extent of oxidative ageing while enhancing high-temperature performance of asphalt binder. Specifically, it was found that the 2% furfural modification had the lowest ageing index after ageing, indicating an improvement in binder oxidative ageing.