Kinetics of fly ash geopolymerization

Autor: Weiliang Gong, Ian L. Pegg, Chen Chen, Werner Lutze
Rok vydání: 2010
Předmět:
Zdroj: Journal of Materials Science. 46:3073-3083
ISSN: 1573-4803
0022-2461
Popis: Based on the wet chemical analysis, we measured and modeled the kinetics of reactions between fly ash and KOH at various temperatures and water-to-solid mass ratios (W/S). We find that three consecutive rate-limiting processes control reaction progress: (1) dissolution or alteration of the glass phase in the fly ash, (2) classical Fick diffusion through a surface layer, and (3) diffusive transport through a more complex gel structure (interstitial gel). This sequence of processes is independent of W/S (0.35–40), temperature (22–75 °C), and KOH concentration (5–10 M). The relative contribution of each process to the overall reaction progress changes with experimental conditions. Only if and when the third process is rate limiting, a fly ash geopolymer forms and develops mechanical strength (sufficiently low W/S ratio provided). The rate of reaction progress decreases significantly, due to slow transport of reacting species to the surface of the glass particles.
Databáze: OpenAIRE
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