This paper reports the use of waste oyster shells as a novel biofiller for hot-mix asphalt (HMA) pavement applications. The effects of different fractions (e.g., 0, 5, 10, 15 wt %) of oyster shell powder (OSP) on the bitumen performance were investigated. The chemical properties of unfilled and OSP-filled asphalts were characterized by means of thin layer chromatography-ionization detection (TLC-FID), Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Thermal characteristics were examined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Physical and rheological properties were assessed through penetration, softening point, ductility, and dynamic shear rheometer (DSR) tests. Results showed that OSP addition increased the resins content, as well as the stiffness of blends. No obvious reactions have occurred between the filler and the asphalt. A higher dose of OSP altered the morphology of the binder, whereas lower and intermediate doses improved its thermal stability and enhanced its low-temperature, rutting, and fatigue performances with respect to the plain asphalt. Overall, the waste oyster shells could be used as filler substitute, not only to improve the quality of road pavements but also to reduce the cost of their construction and solve the waste disposal problems.

This article presents a novel potential bio-based rejuvenator derived from waste pig fat (WPF) for use in recycled asphalt applications. To achieve this purpose, the impact of different doses waste pig fat (e.g., 0, 3, 6, and 9 wt.% WPF) on the reclaimed asphalt pavement binder (RAP-B) performance is investigated. The unmodified and WPF-modified asphalts are characterized by means of Fourier-transform infrared spectroscopy (FT-IR), thin-layer chromatography–flame ionization detection (TLC-FID), scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Physico-rheological properties of asphalt blends are assessed through Brookfield viscometer, softening point, penetration, and dynamic shear rheometer (DSR) tests. TLC-FID data highlighted that incremental WPF addition into RAP-B restored its original balance maltenes-to-asphaltenes ratio; finding which was supported by FT-IR analysis. SEM disclosed that WPF has a great compatibility with the aged asphalt. AFM observations showed that grease treatment induced a decline in surface roughness (i.e., bee structures) and a rise in friction force (i.e., para-phase dimension) of RAP binder. TGA/DSC studies revealed that the bio-modifier not only possesses an excellent thermal stability but also can substantially enhance the binder low-temperature performance. Empirical and DSR tests demonstrated that WPF improved the low-temperature performance grade of RAP-B, reduced its mixing and compaction temperatures, and noticeably boosted its fatigue cracking resistance. The rejuvenation of aged asphalt employing WPF is feasible and can be an ideal approach to recycle both of RAP and waste pig fats.