Influence of spraying on the early hydration of accelerated cement pastes

In practice, most of the studies about the interaction between cement and accelerators is performed with hand-mixed pastes. However, in many applications mixing occurs through spraying, which may affect accelerators reactivity and the microstructure of the hardened paste. The objective of this study...

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Bibliographic Details
Published in:Cement and concrete research 2016-10, Vol.88, p.7-19
Main Authors: Salvador, Renan P., Cavalaro, Sergio H.P., Cano, Miguel, Figueiredo, Antonio D.
Format: Article
Language:English
Subjects:
Accelerator
ACCELERATORS
Additius
Additives
BIOMEDICAL RADIOGRAPHY
Cement
Cement paste
CEMENTS
Ciment
Enginyeria civil
HYDRATES
HYDRATION
Materials i estructures
Materials i estructures de formigó
MATERIALS SCIENCE
Microstructure
MIXING
Mixing process
PRECIPITATION
SCANNING ELECTRON MICROSCOPY
THERMAL GRAVIMETRIC ANALYSIS
X RADIATION
X-RAY DIFFRACTION
Àrees temàtiques de la UPC
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Summary:In practice, most of the studies about the interaction between cement and accelerators is performed with hand-mixed pastes. However, in many applications mixing occurs through spraying, which may affect accelerators reactivity and the microstructure of the hardened paste. The objective of this study is to analyze how the mixing process influences the early hydration of accelerated cement pastes. Isothermal calorimetry, X-ray diffraction, thermogravimetry and SEM imaging were performed on cement pastes produced by hand-mixing and by spraying, using equivalent doses of an alkali-free and an alkaline accelerator and two types of cement. Results showed a great influence of the spraying process on the reactivity of accelerators and on the morphology of the precipitated hydrates. Variations in hydration kinetics caused by the mixing method are explained and the results obtained might have a significant repercussion on how future research on the behavior of accelerated mixes will be performed.
ISSN:0008-8846
1873-3948
DOI:10.1016/j.cemconres.2016.06.005