The effect of w/b and temperature on the hydration and strength of blastfurnace slag cements

The effect of w/b and temperature on the hydration and strength of blastfurnace slag cements

•Later compressive strength of PC is reduce when curing to elevated temperature.•The GGBFS-hydration is very sensitive to the curing temperature.•The rate of hydration of Portland cement and slag depends on the w/b of mixture.•Crossover effect on strength is delayed with 40% GGBFS and absent for 80%...

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Bibliographic Details
Published in:Construction & building materials Vol. 111; pp. 679 - 688
Main Authors: Castellano, C.C., Bonavetti, V.L., Donza, H.A., Irassar, E.F.
Format: Journal Article
Language:English
Published: Elsevier Ltd 15-05-2016
Elsevier B.V
Subjects:
Activation energy
Analysis
Blended cement
Cement paste
Compressive strength
Environmental aspects
Granulate blastfurnace slag
Hydration
Hydration (Chemistry)
Slag cement
Temperature
Water to cement ratio
Temperature
Hydration
Cement paste
Granulate blastfurnace slag
Water to cement ratio
Compressive strength
Activation energy
Blended cement
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Summary:•Later compressive strength of PC is reduce when curing to elevated temperature.•The GGBFS-hydration is very sensitive to the curing temperature.•The rate of hydration of Portland cement and slag depends on the w/b of mixture.•Crossover effect on strength is delayed with 40% GGBFS and absent for 80% GGBFS.•The design of blastfurnace cement may be based on the concepts shown in this paper. The combined effect of water to binder ratio and the curing temperature on the progress of the hydration and the crossover effect on blastfurnace cements containing 40% (BFS40) and 80% (BFS80) of GGBFS was investigated. Tests were performed on pastes with w/b of 0.3–0.5 exposed to 20, 40 and 60°C up to 365days. The hydration progress was monitored by the amount of non-evaporable water and the calcium hydroxide by XRD. A quadratic response-surface model was used to model the crossover effect. Blastfurnace cements present high apparent activation energy (Ea), which is proportional to the GGBFS content in cement, causing a high sensibility to temperature. The non-evaporable water of blastfurnace cements increases with the w/b ratio, temperature and age. The high temperature increasing the early compressive strength and therefore the crossover effect appears after 7days for PC, 28days for BFS40 and it is not detected until 365days for BFS80. The w/b ratio has little or no effect on this phenomenon. To improve the strength of blast-furnace cements, the w/b ratio and the curing temperature will be properly designed according the proportion of slag in cement.
ISSN:0950-0618
1879-0526
DOI:10.1016/j.conbuildmat.2015.11.001