Sulfoaluminate-belite cement from low-calcium fly ash and sulfur-rich and other industrial by-products

The study describes the preparation and characterization of an environmenta lly friendly cement with performance characteristics similar to those of Po rtland cement, from a lime kiln bag house dust, a low-calcium fly ash, and a scrubber sludge. Promising preliminary results show the formation of rela tively low-temperature phases calcium sulfoaluminate (4CaO . 3Al(2)O(3). SO 3) and dicalcium silicate (2CaO . SiO2) at similar to 1250 degrees C if nod ulized raw meal is used for clinker preparation and at 1175 degrees C if po wdered raw meal is used as compared to the similar to 1500 degrees C sinter ing temperature required for Portland cement. Phases of the developed cemen ts were predicted using modified Bogue calculations. Isothermal calorimetri c measurements indicate the hydration properties of the cements are compara ble to ordinary Portland cement. Mechanical properties and microstructural evaluations also were carried out. (C) 1999 Elsevier Science Ltd. All right s reserved.