Evaluating scallop shell waste as a sustainable mineral filler in asphalt mastics: a binder–filler scale study
摘要
Calcium carbonate derived from scallop shells (SCC) represents a sustainable mineral filler for asphalt applications, offering environmental benefits through the valorisation of marine by-products generated by aquaculture and seafood-processing activities in Peru and other coastal countries. Hydrated lime (HL) is widely used to enhance adhesion and moisture resistance in asphalt mixtures; however, in Peru its acquisition and commercialisation are subject to administrative controls due to its regulated status. In this study, SCC was obtained through a physical processing route and evaluated against commercially available HL at the asphalt mastic (binder–filler) scale. Both fillers were characterised using Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray fluorescence (XRF), and X-ray diffraction (XRD). FTIR and TGA confirmed the chemical stability and thermal resistance of SCC under typical asphalt production temperatures, while SEM revealed compact granular particles favourable for binder–filler interaction within the asphalt mastic. The higher alkalinity of HL was associated with stronger chemical affinity, favouring adhesion and moisture resistance, whereas SCC exhibited high purity and a stable calcite structure, providing a physically compatible and thermally stable filler phase. Rheological characterisation of asphalt mastics using multiple stress creep recovery (MSCR) and Linear Amplitude Sweep (LAS) tests showed that SCC produced lower non-recoverable compliance (Jnr) and higher elastic recovery (R), indicating improved resistance to permanent deformation, while HL exhibited superior fatigue performance under cyclic loading. Overall, this study establishes a binder- and mastic-level predictive basis for assessing the mechanical behaviour of SCC-filled systems within a circular economy framework.