Mechanical and durability performance of optimized geopolymer concrete with manufactured artificial aggregates using a tailored mix design method.

In this research, a novel mix design method is developed for geopolymer concrete integrating artificial aggregates. The artificial coarse aggregates are manufactured in the laboratory using a newly developed cut-blade mechanism, and the fine aggregates are produced from construction and demolition waste. The materials used to create the geopolymer concrete primarily include fly ash, glass powder, and construction & demolition waste, along with an alkali activator solution. The mix is optimized using response surface methodology to achieve the best performance at an economical cost. The optimized mix, with an alkali activator solution–to–fly ash ratio of 0.6, achieved maximum compressive and flexural strengths of 44 MPa and 5.2 MPa, respectively. The results show that adding glass powder to the mix can improve the durability of the concrete, as reflected by UPV values of 4200 m/s in water and 3900 m/s under sulfuric acid exposure. Highly accurate predictive models (R² > 0.99) were developed using Response Surface Methodology. The limited formation of crystalline phases in the ITZ suggests that the artificial aggregates do not disrupt the geopolymer matrix structure. These microstructural findings validate the reliability of the ITZ in geopolymer concrete with artificial aggregates, supporting its mechanical performance. In general, the results indicate that the proposed mix design is a sustainable and high-performance which is alternative to traditional concrete.