| People | Locations | Statistics |
|---|---|---|
| Naji, M. |
| |
| Motta, Antonella |
| |
| Aletan, Dirar |
| |
| Mohamed, Tarek |
| |
| Ertürk, Emre |
| |
| Taccardi, Nicola |
| |
| Kononenko, Denys |
| |
| Petrov, R. H. | Madrid |
|
| Alshaaer, Mazen | Brussels |
|
| Bih, L. |
| |
| Casati, R. |
| |
| Muller, Hermance |
| |
| Kočí, Jan | Prague |
|
| Šuljagić, Marija |
| |
| Kalteremidou, Kalliopi-Artemi | Brussels |
|
| Azam, Siraj |
| |
| Ospanova, Alyiya |
| |
| Blanpain, Bart |
| |
| Ali, M. A. |
| |
| Popa, V. |
| |
| Rančić, M. |
| |
| Ollier, Nadège |
| |
| Azevedo, Nuno Monteiro |
| |
| Landes, Michael |
| |
| Rignanese, Gian-Marco |
|
Biesemans, Monique
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (7/7 displayed)
- 2008Undecyltin trichloride grafted onto cross-linked polystyrenecitations
- 2007Reaction mechanism, kinetics and high temperature transformations of geopolymers
- 2007Formation, molecular structure and thermal properties of geopolymers
- 2007Thermal hardening and structure of a phosphorus containing cementitious model materialcitations
- 2007Thermal hardening and stucture of a phosphorus containing cementitious model material: Phosphoric acid-wollastonite
- 2004Wollastonite-phosphoric acid: a modelsystem for fast hardening cements
- 2004Wollastonite-phosphoric acid: a model system for fast hardening cements
Places of action
| Organizations | Location | People |
|---|
article
Reaction mechanism, kinetics and high temperature transformations of geopolymers
Abstract
The reaction kinetics and mechanism of geopolymers are studied. The dissolved silicate concentration decreases from the beginning of the reaction. A characteristic time 'to,vit' for the setting of the reaction mixture is derived from isothermal Dynamic Mechanical Analysis experiments. 'to,vit' increases with SiO2/R2O but goes through a minimum for increasing water content. The reaction is slower for K compared to Na-silicate based systems.<br/>29Si and 27Al solution NMR are used to probe the molecular changes. 27Al NMR and FTIR reveal that an 'intermediate aluminosilicate species' (IAS) is formed from the start of the reaction. The concentration decrease of OH- during low-temperature reaction is related to the formation of IAS. The rate law of this process seems to be obeyed by a total reaction order of 5/3, with a partial order of 1 for OH- and 0 for Na+ in the silicate solution.<br/>During first heating after polymerization water is lost leading to a distortion of the Al environment. According to XRD, no crystallization occurs below 900°C. However, between 950 and 1100°C a crystallization exotherm of nepheline is observed with DSC for a geopolymer with SiO2/Na2O=1.4. Neither Tg of the amorphous geopolymer, nor the shrinkage and expansion around Tg during first heating, cause a measurable heat effect.