Uncovering the Influence of Red Mud on Foam Stability and Pore Features in Hybrid Alkali-Activated Foamed Concrete

This study focuses on investigating the feasibility of using red mud (RM) to enhance foam-stability in hybrid alkali-activated foamed concrete (HAAFC). The water state and flocculation are investigated using low field nuclear magnetic resonance (1H NMR) to explore foam stability in HAAFC. Additionally, the impact of RM on pore features of HAAFC is investigated. The yield stress and surface tension are measured and correlated to the pore sphericity of HAAFC. Experimental results reveal that RM promotes the flocculation formation, reduce free water movement and consequently increases the yield stress of the precursor. RM also expedites the transition from bubbles to pores, thus preventing defoaming and improving the foam stability of HAAFC. Furthermore, the pore sphericity of HAAFC can be increased, as the RM dosage increases. We establish a functional relationship between pore sphericity, surface tension, bubble diameters, and yield stress, providing a predictive tool for estimating pore sphericity in HAAFC.