Performance evaluation and multi-objective optimization of protective slurry seal asphalt mixtures incorporating foundry waste filler and silver nanoparticles

This study presents a comprehensive evaluation of protective slurry seal (SS) asphalt mixtures incorporating foundry waste filler (FWF) and silver nanoparticles (AgNPs). The novelty of this research lies in the combined use of an industrial by-product (FWF) with nanomaterials (AgNPs), a concept that has not been previously reported in SS technology. The main objective is to improve the sustainability and mechanical behavior of SSs by partially replacing natural fillers with FWF and enhancing the microstructural properties through AgNPs. To achieve this, an extensive experimental program was conducted, including chemical characterization (XRF, XRD, FTIR), microstructural analysis (FESEM), and rheological as well as mechanical tests such as wet track abrasion (WTAT), loaded wheel test (LWT), and sand adhesion. The results revealed that FWF significantly improved filler packing and bonding capacity, while the addition of AgNPs enhanced adhesion and rutting resistance. The combined use of FWF and AgNPs produced superior durability compared to the control mixtures. Among the tested samples, the mixture containing 75% FWF and 10% AgNPs provided the most balanced performance, showing improvements of up to 20-25% in adhesion and rutting resistance relative to the reference. A multi-objective optimization approach confirmed this composition as the optimal solution, considering both technical performance and sustainability indicators. These findings also demonstrate practical implications, including reduced material costs, lower environmental footprint, and potential feasibility for large-scale field applications in pavement engineering.