High-temperature properties of a binder based on gypsum-free Portland cement over the temperature range of 20 to 1200 °C

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 degreesC. Over the entire temperature range of 20 to 1200 degreesC 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 degreesC after firing at 1200 degreesC (measured to CSN ISO 1893), which is a performance property comparable to that of alumina cement with a lower Al2O3 content.