Development and Properties of High Purity calcium Aluminate Cements from Indigenous Raw Materials

Calcium aluminate cements were prepared by using lime-stones containing 0.28 to 4.2% silica and Bayer's alumina. The cements made from high silica limestone contained considerable amounts of gehlenite and spinel which appea-red to have adversely affected the refractoriness of the cement. The cements made from low silica limestone and Bayer's alumina were pure and had high refractoriness. By D.T.A, X-ray and microscopial studies it was found that for obtaining cements containing over 90% CaO. Al2O3 and 90% CaO. 2Al2O3, firing temperatures of 1450°C espectively were necessary for essentially completing the solid state reactions. The cements so prepared had satisfactory setting and strength properties. (Mr. B.M. Dutta, Senior Scientific Assistant and M.R.K. Rao, Scientist, National Metallurgical Laboratory, Jamshedpur)