Dynamic reaction of slag-based geopolymer with brick powder: Insights from acoustic emission, heat flow, and relaxation characteristics

Fractal dimension, heat, and NMR relaxation characterizations were employed to monitor the dynamic geopolymerization process of slag-based geopolymer (SBG) with brick powder (BP) in this research. Introducing 30 % BP to SBG resulted in a delay of 6 minutes in the occurrence of polymerization peak, with a 24.12 % decrease in heat peak value. Furthermore, during the rapid polymerization phase, the time of the gel formation in SBG containing 30 % BP was reduced by 34.18 %, accompanied by a 20.91 % decrease in gel water content. The sequence of AE parameters associated with early-age geopolymerization reaction has good fractal characteristics, with fitting coefficient greater than 0.95. Importantly, the heat flow curve, water evolution, and corresponding fractal dimension curves have good correspondence at 0-3 h. Especially, the dissolution peak and polymerization peak of the heat flow curve basically coincide with the fractal dimension curve. The fractal dimension not only serves as an effective indicator for evaluating the geopolymerization process but also compensates for the limitations of calorimetry in characterizing reaction processes with relatively small particle migration and local heat release.