Use of higher proportions of fly ash as a cement replacement in concrete has obvious environmental and performance benefits but high volumes of fly ash are not commonly used due to perceived lower early age strengths. In this investigation, addition of cement kiln dust (CKD) and gypsum to activate the fly ash was studied and the proportions used in the paste mixes were designed to optimize the mixture ingredients to achieve the highest early age compressive strength. Change of mineral phase composition and micro structure of the composites was analyzed. It was found that CKD was much more effective in activating the fly ash than gypsum. Appreciable early age compressive strengths were achieved for fly ash contents up to 60% of the binder and these observations were supported by analysis of the mineral phases.
Bibliographical noteNOTICE: this is the author’s version of a work that was accepted for publication in Construction and Building Materials. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Construction and Building Materials [Vol 71 (2014)] DOI: 10.1016/j.conbuildmat.2014.08.015.
FunderEngineering and Physical Sciences Research Council (EPSRC) under Grant [EP/J016055/1].
- high volume fly ash (HVFA) concrete
- early age strength (EAS)
- cement kiln dust (CKD)
- mineral phases