Characterizing the mechanisms and alkali-silica reaction behavior of novel and non-traditional alkali-activated materials

This study investigates the Alkali-Silica Reaction (ASR) behavior of non-traditional alkali-activated materials (NAAMs) utilizing unconventional precursors, including calcined clays (CC), volcanic ashes (VA), ground bottom ashes (GBA), and fluidized bed combustion ashes (FBC). Using ASTM-based accelerated and non-accelerated methods, ASR expansions were assessed across aggregates with varying reactivity (R0, R1, R2, and R3). The research reveals a critical interaction between initial drying shrinkage and ASR expansion, where shrinkage offsets early ASR-induced expansions. Microstructural analysis via SEM and EDS highlights unique alumina-enriched ASR products with low-viscosity and limited expansion potential, attributed to the absence of calcium-rich gels. The study evaluates alternative ASR prediction methods, finding moisture transport parameters unreliable but pore solution ionic composition, especially high alumina levels, as strong indicators of ASR mitigation. A novel ASR Inhibition Efficiency Score (AES) quantifies NAAMs’ mitigation capacity, showcasing the exceptional performance of CC- and GBA-based NAAMs against ASR in highly reactive aggregates.