Abstract
Five batches of low cement zircon- magnesia concretes were prepared using dead burned magnesite aggregate, fine zircon sand and high alumina refractory cement.The concretes were shaped and fired at 1500°C. Densification parameters were determined through bulk density (BD) and apparent porosity (AP). High temperature phases were examined by XRD. A correlation between the densification properties and the phases formed was made through SEM examination of the microstructure.The cold crushing strength, thermal shock resistance (TSR) and refractoriness under load (RUL) of the fired concretes were evaluated.The results showed that increasing zircon is beneficial to densification up to 20% after which a decrease in sintering occurred. Zirconia evolved mainly in tetragonal form beside spinel, periclase and CaO, MgO- silicate glassy phases. The concretes showed high cold crushing strength and good resistance to both thermal shock (Dt=1000°C) and refractoriness under load (0.2Mpa).
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