@article{Tawfik_Abd El-Raoof_Katsuki_MacKenzie_Komarneni_2016, title={K-Based Geopolymer from metakaolin: roles of K/Al ratio and water or steam Curing at different temperatures}, volume={66}, url={https://materconstrucc.revistas.csic.es/index.php/materconstrucc/article/view/1984}, DOI={10.3989/mc.2016.03115}, abstractNote={K-based geopolymer binder was prepared by reacting metakaolin with alkaline solutions having different potassium contents and by water curing at room temperature and 80 °C as well as steam curing at 150 and 180 °C. The phase formation, microstructure and Al and Si nearest neighbor environments were studied using XRD, TEM and <sup>27</sup>Al and <sup>29</sup>Si MAS NMR spectroscopy, respectively. The results revealed that amorphous alumino-silicates were predominant in geopolymer prepared by curing up to 28 days at room temperature or at 80 °C. The amorphous alumino-silicates persisted after hydrothermal treatment at 150 °C/48 hrs and even at 180 °C/30 hrs. However, the samples cured hydrothermally at 180 °C/48 hrs revealed formation of crystalline potassium aluminum silicate and chabazite phases. The Al nearest neighbor environments was not significantly affected by increasing the K/Al ratio up to 1.55 or by the curing temperatures. On the other hand, the geopolymer reaction appears to have increased when cured at 80 °C or steam cured at 150° and 180 °C and crystalline aluminosilicates resulted when the geopolymer sample was hydrothermally treated at 180 °C/48 hrs.}, number={322}, journal={Materiales de Construcción}, author={Tawfik, A. and Abd El-Raoof, F. and Katsuki, H. and MacKenzie, K. J.D. and Komarneni, S.}, year={2016}, month={Jun.}, pages={e081} }