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Assessment of the protective effect of carbonation on portlandite crystals
The kinetics of many reactions important to cement hydration and use are not well understood: this is in part due to the great complexity of many supposedly “simple” processes. One such process, carbonation of portlandite, Ca(OH)2, in moist air at ∼23 °C has been investigated by microscopy and microchemical analysis. Single crystals of portlandite were grown, carbonated at relative humidities between ∼25 and ∼90%, and the transport properties of the self-generated calcite, CaCO3, product film were determined. The calcite films thus grown within days or weeks varied in thickness but typically were polycrystalline and epitaxial: a variety of morphologies and surface features are recorded. Permeation was measured by determining the time taken for Ca2 + ions, arising from the Ca(OH)2 substrate, to diffuse through the calcite coat into initially pure water. The spontaneous formation of self-protecting films on concrete has long been envisaged: results demonstrate that passivation can actually be achieved.
Assessment of the protective effect of carbonation on portlandite crystals
The kinetics of many reactions important to cement hydration and use are not well understood: this is in part due to the great complexity of many supposedly “simple” processes. One such process, carbonation of portlandite, Ca(OH)2, in moist air at ∼23 °C has been investigated by microscopy and microchemical analysis. Single crystals of portlandite were grown, carbonated at relative humidities between ∼25 and ∼90%, and the transport properties of the self-generated calcite, CaCO3, product film were determined. The calcite films thus grown within days or weeks varied in thickness but typically were polycrystalline and epitaxial: a variety of morphologies and surface features are recorded. Permeation was measured by determining the time taken for Ca2 + ions, arising from the Ca(OH)2 substrate, to diffuse through the calcite coat into initially pure water. The spontaneous formation of self-protecting films on concrete has long been envisaged: results demonstrate that passivation can actually be achieved.
Assessment of the protective effect of carbonation on portlandite crystals
Galan, I. (author) / Glasser, F.P. (author) / Baza, D. (author) / Andrade, C. (author)
Cement and Concrete Research ; 74 ; 68-77
2015
10 Seiten, 12 Quellen
Article (Journal)
English
Assessment of the protective effect of carbonation on portlandite crystals
British Library Online Contents | 2015
Assessment of the protective effect of carbonation on portlandite crystals
| Online Contents | 2015
| Springer Verlag | 2022