Impact of silica fume, fly ash, and metakaolin on the thickness and strength of the ITZ in concrete. (October 2019)

• Record Type: Journal Article
• Authors: Nežerka, V.; Bílý, P.; Hrbek, V.; Fládr, J.
• Is Part Of: Cement & concrete composites. Volume 103(2019)
• Page Start: 252
• Page End: 262
• Publication Date: 2019-10
• Subjects: Concrete -- ITZ -- Strength -- Silica fume -- Fly ash -- Metakaolin; Composite-reinforced concrete -- Periodicals; Concrete -- Periodicals; Composite materials -- Periodicals; Composites de ciment -- Périodiques; Béton -- Périodiques; Composites -- Périodiques; Béton léger -- Périodiques; Cement composites; Composite materials; Composite-reinforced concrete; Concrete; Lightweight concrete; Periodicals; Electronic journals; 620.135
• DOI: 10.1016/j.cemconcomp.2019.05.012
• Languages: English
• ISSNs: 0958-9465

Abstract

Abstract: The interfacial transition zone (ITZ) has a major detrimental impact on the structural performance of concrete. This negative impact can be modulated by introducing mineral admixtures to a concrete mix, which fill the excessive voids within ITZ and react with portlandite to form more compact products. The approach described here, consisting of characterization of phases and micromechanical modeling, enabled assessment of the effect of silica fume, fly ash, and metakaolin on ITZ thickness and strength. The proposed model was based on the Mori-Tanaka scheme coupled with an estimation of deviatoric stress within ITZ. This study suggests that silica fume is efficient in reducing ITZ thickness, while the addition of fly ash more significantly contributes to ITZ strength. Moderate replacements of Portland cement for silica fume or fly ash, up to 20%, can positively influence concrete performance; in case of metakaolin, replacement up to 10% is recommended.