Sustainable Ultra-High-Performance Concrete: Incorporating Nano-Eggshell Waste for Improved Strength and Durability

Abstract

This study examines the mechanical and microstructural properties of ultra-high-performance concrete (UHPC) incorporating nano-eggshell (NES) particles as a sustainable alternative to conventional nanofillers. Eggshell waste, consisting primarily of calcium carbonate, was processed through cleaning, calcination, and grinding to obtain nanosized particles. UHPC mixtures with varying NES contents (1-5%) were prepared and evaluated for compressive strength, splitting tensile strength, and sorptivity at different curing ages. The results indicate that the optimal NES dosage of 3% significantly enhanced the compressive strength of UHPC by 4.9%, 6.0%, and 4.5% at 7, 28, and 90 days, respectively, compared to the reference mixture. The splitting tensile strength at 28 days also improved by 16.9% with 3% NES. The sorptivity of UHPC was reduced by 28% at the optimal NES content, indicating its improved durability. XRD analysis revealed the presence of calcium carbonate and its interactions with the cementitious matrix. The performance improvements were attributed to the nanofiller effect, accelerated hydration, and microstructural refinement induced by NES particles. However, excessive NES addition beyond the optimal dosage led to slight reductions in the mechanical properties owing to agglomeration effects. The findings demonstrate the potential of nano-eggshell waste as a sustainable and performance-enhancing alternative in UHPC, contributing to the development of eco-friendly construction material.