Impact of silica fume, fly ash, and metakaolin on the thickness and strength of the ITZ in concrete

By V. Nežerka, P. Bílý, V. Hrbek, J. Fládr. Cement & Concrete Composites, 2019

212 citations recorded by the source corpus.

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.

Subfields: Civil and Structural Engineering, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/9e1bc60ed60589a89886c5ced8803af41501f01e