Thermal stability study of alkali-metakaolin-based cementitious materials

Geopolymer;  thermal stability;  residual compressive strength;  differential thermal analysis;  Thermogravimetric analysis

Fly ash bleaching, G alkali-metakaolin-based cementitious material Geopolymer (ordinary cement as the contrast sample) and water were mixed in proportion to form 3 cm×3 cm×3 cm test blocks and cured for 28 days. The test block is calcined at a specified temperature and time, and its thermal stability is judged by its remaining compressive strength. The test results show that the residual compressive strength of Geopolymer increases with the increase of calcination temperature, and shows a significant increase trend from 800 °C to 1 000 °C, while the residual compressive strength of ordinary cement decreases with the increase of calcination temperature. Differential thermal analysis and thermogravimetric analysis of the hydration products of Geopolymer and cement were carried out, and it was found that Geopolymer had excellent thermal stability properties, which may be caused by the special hydration products of Geopolymer.