Borgnakke, C. ; Hansen, W. ; Kang, Y. ; Liu, Z. ; Koenders, E. A. B. (2012)
Cryogenic suction pump mechanism for combined salt-and frost exposure.
Konferenzveröffentlichung, Bibliographie
Kurzbeschreibung (Abstract)
Freezing of water can be explained by the thermodynamic properties of the water due to the influence of temperature, pressure and special effects such as surface tension and salt solution. Gibbs free energy curves for ice and pore liquid containing different concentrations of NaCl (0-6%) are presented. These curves explain the onset of freezing in pores when the energy level for solid ice and pore liquid containing salt are equal. Upon further cooling a nonequilibrium condition develops since the Gibbs function for pure ice is less than the Gibbs function for the liquid. The theory also explains why ice nucleation is developing in the largest pores containing liquid, including air-voids. Below the nucleation temperature, a vacuum with low partial pressure of the water develops around the ice which starts a cryogenic suction pump. For a closed system (i.e. no external liquid) partial pore-drying develops leading to specimen shrinkage. In air-entrained concrete the ice growth may be accommodated within the pore system without structural damage. In the case external liquid is present, such as when the surface contains a salt solution, pore suction attracts surface liquid, and additional ice growth may not be accommodated within the pore system. Thus, a net expansion occurs. Frost expansion due to crystal growth is time-dependent and progresses as long as liquid is available and until thermodynamic equilibrium is re-established at a given temperature.
Typ des Eintrags: | Konferenzveröffentlichung |
---|---|
Erschienen: | 2012 |
Autor(en): | Borgnakke, C. ; Hansen, W. ; Kang, Y. ; Liu, Z. ; Koenders, E. A. B. |
Art des Eintrags: | Bibliographie |
Titel: | Cryogenic suction pump mechanism for combined salt-and frost exposure |
Sprache: | Englisch |
Publikationsjahr: | April 2012 |
Verlag: | RILEM Publications |
Buchtitel: | Second International Conference on Microstructural-related Durability of Cementitious Composites, RILEM Proceedings pro083, 11-13 April, 2012, Amsterdam, The Netherlands |
URL / URN: | http://resolver.tudelft.nl/uuid:ebc6e80e-3c9e-46a5-80be-c729... |
Kurzbeschreibung (Abstract): | Freezing of water can be explained by the thermodynamic properties of the water due to the influence of temperature, pressure and special effects such as surface tension and salt solution. Gibbs free energy curves for ice and pore liquid containing different concentrations of NaCl (0-6%) are presented. These curves explain the onset of freezing in pores when the energy level for solid ice and pore liquid containing salt are equal. Upon further cooling a nonequilibrium condition develops since the Gibbs function for pure ice is less than the Gibbs function for the liquid. The theory also explains why ice nucleation is developing in the largest pores containing liquid, including air-voids. Below the nucleation temperature, a vacuum with low partial pressure of the water develops around the ice which starts a cryogenic suction pump. For a closed system (i.e. no external liquid) partial pore-drying develops leading to specimen shrinkage. In air-entrained concrete the ice growth may be accommodated within the pore system without structural damage. In the case external liquid is present, such as when the surface contains a salt solution, pore suction attracts surface liquid, and additional ice growth may not be accommodated within the pore system. Thus, a net expansion occurs. Frost expansion due to crystal growth is time-dependent and progresses as long as liquid is available and until thermodynamic equilibrium is re-established at a given temperature. |
Freie Schlagworte: | cryogenic suction, frost expansion, Gibbs-free energy, salt frost attack |
Fachbereich(e)/-gebiet(e): | 13 Fachbereich Bau- und Umweltingenieurwissenschaften 13 Fachbereich Bau- und Umweltingenieurwissenschaften > Institut für Werkstoffe im Bauwesen |
Hinterlegungsdatum: | 08 Jun 2015 14:54 |
Letzte Änderung: | 28 Apr 2017 08:42 |
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