Abstract
For many years, coal combustion by-products (CCPs) have been broadly used as a replacement for Portland cement in the production of different types of concrete: in embankments and soil stabilization; however, use of these materials in the pavement industry has been very limited, and few research studies have been conducted in this area. Spray dryer absorber (SDA) materials are a type of CCPs that are derived from flue-gas desulfurization of coal-fired power plants. The current study explores the effect of the incorporation of SDA materials on the high-temperature rheological performance of warm mix asphalt (WMA) mastics. To do this, SDA material and dolomite powder (as a reference filler) were first investigated in terms of different physical and chemical properties, including particle size distribution, specific gravity, Rigden voids, morphological properties, X-ray diffraction (XRD), and X-ray fluorescence (XRF). The fillers were then incorporated in PG 58-28 asphalt binder with 5%, 15%, and 25% replacement of the asphalt binder by volume, making a total of six asphalt mastics. The high-temperature performance of SDA-based mastics was evaluated using a dynamic shear rheometer (DSR) machine and compared with that of dolomite-based mastics. The rheological properties were assessed by performing temperature sweep tests for complex modulus (G*), phase angle (δ), multiple stress creep (Jnr) at different loading levels, and aging resistance tests. The experimental results indicate that SDA-based mastics have higher resistance to permanent deformation and higher rutting resistance and show better performance in terms of aging compared to the reference dolomite-based mastics with similar filler volume concentrations. Based on the results, it can be concluded that the incorporation of SDA powders in asphalt binders can pave the way to achieving a sustainable, long-lasting, cost-effective, and flexible pavement.
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