Which type of cement is produced by grinding clinkers formed by calcining bauxite, lime, iron oxide with a little ferric oxide, silica magnesia, etc? (Note that alumina content in this type of cement should NOT be less than 32%.)
Explanation: High alumina cement: ● High alumina cement (HAC) is a special cement, manufactured by mixing bauxite (Aluminum ore) and lime (Limestone) at a certain temperature. ● The setting time of high alumina cement is greatly affected by the addition of plaster of Paris, lime, Portland cement, and organic matter. Thus, no additives should be used. ● High alumina cement is very reactive and has very high compressive strength. ● As per IS Code: 6452:1989, the maximum initial and final setting time for high alumina cement is the same as ordinary cement. ● Due to the property of the cement, in actual the alumina cement has a higher initial setting time but a lower final setting time as compared to ordinary cement. ● High alumina cement is produced by fusing together in such a way that the percentage of alumina should not be less than 32%.The initial setting time for this test is 3.5 hrs and the final setting time is 5 hrs.