Development and properties of high calcium aluminate cements from indigenous raw materials

Abstract

Calcium aluminate cements were prepared by using limestones 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 appeared 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 respectively 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)