caa a22 4500 463223969 CHVBK 20180405153221.0 cr unu---uuuuu 170326e20070501xx s 000 0 eng 10.1007/s10853-006-0818-9 doi (NATIONALLICENCE)springer-10.1007/s10853-006-0818-9 Dissolution processes, hydrolysis and condensation reactions during geopolymer synthesis: Part II. High Si/Al ratio systems [Elektronische Daten] [K. Sagoe-Crentsil, L. Weng] The mechanisms of speciation of aluminate and silicate phases during dissolution and condensation stages of alumino-silicate geopolymer reactions characterised by Si/Al≥3, have been investigated and the results compared to predictions of the partial charge model. Solid-state nuclear magnetic resonance (NMR) traces indicate that free [Al(OH)4]− species, present in lower silicate formulations such as Si/Al≤1, do not occur in the present systems, suggesting that the condensation reaction between [Al(OH)4]− and silicate species is fairly quick and is consumed as soon as it is formed. This observation is also consistent with both calorimetric measurements and model predictions, as the condensation time increased exponentially with increased Si/Al ratio in the geopolymeric phase, indicating again that the high content of Al species in the gel phase greatly enhanced the condensation rate. The experimental observations suggest that the condensation process in these systems occurs in two stages: (a) quick condensation between aluminate and silicate species; followed by (b) a slow condensation stage solely involving silicate species. Springer Science+Business Media, LLC, 2006 Sagoe-Crentsil K. CSIRO Manufacturing and Infrastructure Technology, PO Box 56, 3190, Highett, VIC, Australia aut Weng L. Department of Materials Science, Shenzhen Graduate School, Harbin Institute of Technology, University Town, 518055, Xili, Shenzhen, People's Republic of China aut Journal of Materials Science Kluwer Academic Publishers-Plenum Publishers; http://www.springer-ny.com 42/9(2007-05-01), 3007-3014 0022-2461 42:9<3007 2007 42 10853 https://doi.org/10.1007/s10853-006-0818-9 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10853-006-0818-9 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Sagoe-Crentsil K. CSIRO Manufacturing and Infrastructure Technology, PO Box 56, 3190, Highett, VIC, Australia aut NATIONALLICENCE 700 1- Weng L. Department of Materials Science, Shenzhen Graduate School, Harbin Institute of Technology, University Town, 518055, Xili, Shenzhen, People's Republic of China aut NATIONALLICENCE 773 0- Journal of Materials Science Kluwer Academic Publishers-Plenum Publishers; http://www.springer-ny.com 42/9(2007-05-01), 3007-3014 0022-2461 42:9<3007 2007 42 10853 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer