Optimum Utilization of Coal Ash as Additive for Blended Cement Production
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Date
2016-02
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Addis Ababa University
Abstract
The government of Ethiopia has given a great attention for establishment of chemical industries since 2011. The establishments of this chemical industry begin with coal based urea plant with an integration of a 90MW coal based thermal power plant for electric source. This power plant produces 75,000 ton per annum of coal ash as a waste during the production process. Using this ash, as raw material is an enormous opportunity both for cement and thermal power industries to reduce their environmental impact. The aim of the research is to stress the characterization and optimum utilization of coal ash as additive for blended cement production. In this study coal sample was collected from Yayu and burned at home to get ash. The characteristics of coal ash and cement raw materials were investigated by classical and analytical testing methods. 15 types of blended cements having a solid residue of ≤ 10, (10-16], and (16-20]% on 45μm sieve were produced by inter-grinding of coal ash, clinker and gypsum in laboratory ball mill, with the clinker replacement levels of 20, 25, 30, 35, and 40% by mass. The performance of the cements was evaluated by conducting the following tests: setting time, soundness and compressive strength. The results showed that Yayu coal ashes possess sufficient pozzolanic characteristics to be used in production of blended cement, and the optimum clinker replacement level by this ash can range between 20-25% by mass. Key words: setting time, soundness, compressive strength, pozzolanic, coal ash, blended cement,
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setting time; soundness, compressive strength; pozzolanic; coal ash; blended cement