Incorporation of Eggshell Powder in Metakaolin-Based Geopolymer Concrete Exposed to Elevated Temperatures

Abstract

Recently, due to the high demand for concretes with a low carbon footprint during production, geopolymer concretes have been introduced. Metakaolin (MK) is widely used by researchers in the production of geopolymer concrete due to its ability to replace cement and its high silica content. This study investigated the mechanical properties and high-temperature performance of geopolymer mortars produced using eggshell powder (ESP), an organic waste, as a substitute for metakaolin (MK). Within the scope of the study, ESP was used to partially replace MK at 5%, 10%, 15%, 20%, 25%, 30%, 35%, and 40% (by weight), and the flexural and compressive strengths, as well as the water absorption values were determined. In addition, the samples were exposed to temperatures of 200 °C, 500 °C, and 800 °C to determine the residual compressive strengths of the samples and to examine the internal structures of the selected samples. The results showed that using ESP up to a specific rate increased the strengths of MK-based geopolymer mortars. Additionally, 25% ESP yielded the best results regarding the mechanical properties and high-temperature performance of geopolymers. © 2025 Elsevier B.V., All rights reserved.