Ceramics-Silikáty 45 (4) 151-157 (2001)

HIGH-TEMPERATURE PROPERTIES OF A BINDER BASED ON GYPSUM-FREE PORTLAND CEMENT OVER THE TEMPERATURE RANGE OF 20 TO 1200°C

V. Ševčík, F. Škvára

Hydration products of GF cement differ from those of Portland cement in morphology of Ca(OH)₂ which in hydrated GF cement is in an extremely fine, and for the most part X-ray amorphous form. The morphologically different Ca(OH)₂ in hardened GF cement is very disadvantageous with respect to the development of strength at temperatures at which Ca(OH)₂ is decomposed. This fact is responsible for a rapid decrease in strength of hydrated GF cement at about 500°C. Over the entire temperature range of 20 to 1200°C hydrated GF cement exhibits a higher post-firing strength than Portland cement made of clinker of the same composition. Mortar of GF cement with corundum aggregate and stabilized with 15% silica fume attained t_0.5 = 1189°C after firing at 1200 °C (measured to ČSN ISO 1893), which is a performance property comparable to that of alumina cement with a lower Al₂O₃ content.

Keywords: Gypsum-free, Portland cement, Refractory, High-temperature properties