Characterization of chemosynthetic H3PO4-Al2O3-2SiO2 geopolymers

Pure chemosynthetic Al2O3-2SiO(2) powders fabricated by a sol-gel method exhibit high phosphoric acid activated properties and high compressive strengths. The phosphoric acid-activated properties could be characterized by compressive strength. The phase structure evolution of synthetic powders and the resulting geopolymers were investigated by DTA-TG, XRD, FTIR and MAS NMR analysis. These results show that the phosphoric acid-activation region of the synthetic powders was in the range of 200800 degrees C, which was much lower than the temperature at which kaolinite was converted into metakaolinite. P-31 MAS NMR analysis revealed that [PO4] tetrahedra were part of the geopolymer structure. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.