Structural Concrete, 2025 (SCI-Expanded, Scopus)
Increasing environmental concerns and the rapid depletion of natural resources have recently increased the need for sustainable construction materials. In this context, the development of environmentally friendly binders has become an important research area in concrete technology. The originality of this study is that it adopts a waste utilization approach to the production of geopolymer foam concrete using eggshell waste as a binder. In this study, eggshell powder was utilized as a partial replacement for pumice powder in the geopolymer foam concrete mixtures. The aim of this study is to investigate the physical, mechanical, high temperature, freeze–thaw resistance, and sulfate resistance of mixtures prepared to use different proportions of eggshell powder instead of pumice powder. The study focuses on designing lightweight geopolymer foam concretes that integrate the use of waste materials with structural performance. The results obtained show that there are significant increases in 7- and 28-day compressive and flexural strengths with the use of 10%–20% eggshell powder. In addition, thermal conductivity increased at optimum additive rates, and porosity and water absorption values reached minimum levels. A 130% increase in compressive strength at 200°C was observed with a 10% additive rate. SEM analyses revealed that N–A–S–H, C–S–H, and zeolitic phases formed a compact and stable structure in the samples, and the microstructure showed high resistance to environmental effects. This study demonstrates the performance potential of environmentally friendly and low-cost binder alternatives in geopolymer foam concretes. The optimum dosage of eggshell powder was determined as 20%, providing the best balance between mechanical and durability performance. At this replacement level, 28-day compressive strength increased by more than 40% compared to the control mixture, while flexural strength showed a similar upward trend. In addition, exposure to 200°C resulted in up to a 130% improvement in compressive strength, highlighting the significant strength enhancement achieved with eggshell incorporation. In future studies, new developments can be provided in the field of sustainable building materials by evaluating different types of waste with similar binding purposes.