Early age hydration of cement pastes with alkaline and alkali-free accelerators for sprayed concrete
By R. Salvador, S. Cavalaro, I. Segura, A. Figueiredo, J. Pérez. 2016
244 citations recorded by the source corpus.
Abstract The objective of this study is to evaluate the early age hydration mechanisms of accelerated CEM I pastes. Liquid phase analysis, conductimetry, isothermal calorimetry, in situ XRD and SEM were performed on cement pastes produced with equivalent doses of an alkaline accelerator (sodium aluminate solution) and of an alkali-free accelerator (aluminum sulfate solution). Results showed that the addition of these chemicals first changes the ionic equilibria of the medium by the consumption of Ca 2+ and SO 4 2− ions from the liquid phase. The alkali-free accelerator contributes to the rapid formation of ettringite, as well as to a faster rate of alite dissolution and hydration. The aluminate accelerator leads to AFt and AFm formation, rapidly depleting gypsum and filling up the space, inhibiting further alite hydration. According to the results, variations in cement hydration mechanisms caused by accelerators with different chemical compositions are explained.
Subfields: Civil and Structural Engineering
View Paper: https://www.semanticscholar.org/paper/3962bd055209e18aebdf415535271584de663624
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In Civil and Structural Engineering
Citations in the corpus
- Effects of sulfates on the hydration of Portland cement – A review (2021, background): “As the alkali-free accelerator is based on an aluminum sulfate solution (while the alkaline type is based on sodium aluminate solution), the sulfates from the chemical admixture provide more sulfate to the solution even though the sulfate concentration in solution was always lower than that in the r”