Ceramics-Silikáty 45, (4) 151 - 157 (2001) |
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HIGH-TEMPERATURE PROPERTIES OF A BINDER BASED ON GYPSUM-FREE PORTLAND CEMENT OVER THE TEMPERATURE RANGE OF 20 TO 1200°C
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Ševčík Václav 1, Škvára František 2
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1 Air Force Technical Institute,
Mladoboleslavská, 197 06 Prague, Czech Republic
2 Department of Glass and Ceramics,
Institute of Chemical Technology,
Technick· 5, 166 28 Prague, Czech Republic
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Keywords: Gypsum-free, Portland cement, Refractory, High-temperature properties
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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 t0.5 = 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. |
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