Relations between the structural characteristics and compressive strength in metakaolin based geopolymers with different molar Si/Al ratios
Ceramics International, cilt.41, sa.8, ss.10192-10198, 2015 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 41 Sayı: 8
- Basım Tarihi: 2015
- Doi Numarası: 10.1016/j.ceramint.2015.04.125
- Dergi Adı: Ceramics International
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
- Sayfa Sayıları: ss.10192-10198
- Anahtar Kelimeler: Compressive strength, Geopolymer structure, Metakaolin
- Boğaziçi Üniversitesi Adresli: Evet
Özet
Abstract X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and compressive strength measurements were performed to fully characterize metakaolin-based geopolymers with molar Si/Al ratios of 1.12, 1.77 and 2.20 in order to establish structure-performance relationships in this system. XRD results showed that the geopolymer samples with Si/Al ratio of 1.12 contained crystalline components, namely zeolite A and/or sodalite phases, whereas geopolymers with Si/Al ratio of 1.77 and 2.20 were 'X-ray amorphous' with minor amount of quartz content. The microstructure as revealed from SEM verified that geopolymer with Si/Al ratio of 1.12 consisted of crystalline components whereas samples with Si/Al ratio of 1.77 and 2.20 included amorphous microstructures. The position and width of the main band in FTIR spectra is found to systematically increase with increasing molar Si/Al ratio. The intensity of this band decreased with increasing Si content in the system indicating increased geopolymerization. This increase was related with formation of a three dimensional structure with stronger bonding environment with increasing SiO2 incorporation in geopolymer matrix. Compressive strength of these samples were also found to increase systematically with increasing molar Si/Al ratio. The evolution of the structural characteristics obtained from spectroscopy, diffraction and microscopy are shown to be directly correlated with the results of compressive strength measurements performed on these geopolymers.