Phase-Structure Transformation in Low-Si/Al-Ratio Geopolymers

Abstract:

To obtain low-Si/Al-ratio geopolymers and overcome the disadvantage of impure raw materials, amorphous Al₂O₃-SiO₂ powder was first prepared using a sol-gel method in accordance with specially designed chemical compositions. The composition of the geopolymers was designed according to the NaA zeolite composition (Si/Al/Na atom ratio is 1:1:1), and the zeolite crystal structure was obtained by geopolymers with high Na/Al ratios through hydrothermal processing at 90oC for 6 h. The geopolymers with Si/Al ratios ranging from 0.9 to 1.05 exhibited amorphous structures after being cured at 60oC for 24 h; however, the geopolymer sample with a Si/Al ratio of 1.1 exhibited crystallization. After the hydrothermal treatment of these geopolymers , the XRD, SEM and NMR results show that the phase structure of the geopolymers may transform into a crystalline structure under appropriate compositions and external conditions. Hence, the alkalinity, Si/Al ratio and hydrothermal conditions determined the crystallinity of the geopolymers that were synthesized.

• Periodical: Key Engineering Materials (Volumes 602-603)
• Pages: 76-79
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.602-603.76
• Online since: March 2014
• Authors: Yi Pin Wang, Yan He, Jing Liu, Xue Min Cui
• Keywords: Amorphous Materials, Geopolymer, Phase Transformation, Zeolite

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