Performance of Cold-Mix Asphalt with Calcined Eggshell Powder–Activated GGBFS Filler

Cold-mix asphalt (CMA) can be produced more sustainably by using byproducts as fillers instead of conventional materials such as cement. This study used a new filler of calcined eggshell powder (cESP)-activated ground granulated blast furnace slag (GGBFS) in CMA mixtures to improve performance and reduce curing time. The outcomes were compared with those of CMA mixtures comprising limestone and cement fillers and two hot-mix asphalt (HMA) mixtures with AC10 and AC20 asphalt binders. This study used indirect tensile strength, cracking tolerance, and rutting performance as basic performance measurements and used moisture loss, volumetric properties, and microstructural analysis to visualize the mechanism behind the strength development. The results reveal that cESP-activated GGBFS can improve the performance of CMA mixtures at both early and late ages, and performs comparably to cement filler CMA and conventional HMA mixtures for application in pavement structural layers. The hydration products were visualized using microstructural analysis in the cement and cESP-activated GGBFS CMA mixtures, which can enhance the bond strength in the mixtures. Hydration reaction and moisture loss together contributed to strength development in cement and cESP-activated GGBFS CMA mixtures. Conversely, strength improvement in limestone and pure GGBFS mixtures was entirely attributable to the loss of water by evaporation. Because GGBFS and eggshells are byproducts, utilizing them in CMA construction will be economically and environmentally advantageous, and lead to improved mechanical performance and a shorter curing time.