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Fly ash used as an admixture material in cement has been applied to mass concrete amongst others for reduction of hydration heat and regarded by the cement industry as an essential material in concrete manufacture that reduces greenhouse gas emission and has a cost-saving effect. However, the downside of using fly ash is that it reduces the initial strength of concrete and resistance to neutralization. In this study, it was examined whether addition of calcium sulfoaluminate (CSA) could improve the initial strength of concrete and the micropore structure as a means to ameliorate the reduced initial strength and neutralization resistance caused by increased porosity resulting from the use of fly ash. Up to 30% of cement was substituted with fly ash, while the amount of CSA substitution was 8% of the fly ash weight. The results of the experiment showed that increasing the amount of fly ash resulted in an increase in the distribution of pores with a diameter of more than 0.1um. In particular, 30% substitution resulted in higher porosity distribution in the 20nm~0.1um and over 1um distribution ranges compared to cement. On the other hand, adding CSA in an amount equivalent to 8% of the fly ash weight resulted in the pores having an average particle diameter of 0.18um with a relatively low distribution of pores that are larger than 0.5um. Based on this result, it was determined that the use of CSA would enhance the initial strength and neutralization resistance.
Grant : 인공지반구조물의 초장수명 철근콘크리트 개발
Supported by : 한국건설기술연구원
