Low-energy alinite cement production by using soda waste sludge

Uçal, Gültekin Ozan
Increased environmental awareness and the concept of sustainable development have impacts on cement industry as on many other fields. Alinite cement which was developed in the 1970s may be an alternative inorganic, low energy binding material. In this study, synthesis and optimization of the properties of alinite cement was carried out by using soda waste sludge as a raw material. Soda waste sludge was mixed with limestone, clay, and iron ore in different proportions. All mixes were burned at 1050oC or 1150oC to produce alinite cement clinker. 1, 2, and 4 hours of calcination times were applied and the clinkers were examined by chemical and mineralogical analysis. Optimal burning temperature and calcination time were determined. Chemical analyses were carried out by X-Ray Fluorescence spectroscopy and by wet chemical analysis. Mineralogical analyses were performed by X-Ray Diffraction (XRD) technique. Based on chemical and mineralogical analyses, suitable clinkers were selected and produced in larger quantities. They were ground and mixed with gypsum. Effects of gypsum content on compressive strength and calorimetry values were investigated and compared to a commercially available portland cement. Mineral phases present in the course of hydration were determined by powder XRD. Observation of crystal structures at different hydration ages was also carried out, by scanning electron microscopy (SEM). It was shown that soda waste sludge can be used to produce low-energy and low-CO2 alinite cement with sufficient properties. Compressive strengths comparable to ordinary portland cement can be achieved with partial replacement of limestone with soda waste sludge in the raw mix. Short setting time of alinite cement associated with fast initial rate of reaction was also noted.
Citation Formats
G. O. Uçal, “Low-energy alinite cement production by using soda waste sludge,” M.S. - Master of Science, Middle East Technical University, 2016.