Print Email Facebook Twitter Cryogenic suction pump mechanism for combined salt-and frost exposure Title Cryogenic suction pump mechanism for combined salt-and frost exposure Author Borgnakke, C. Hansen, W. Kang, Y. Liu, Z. Koenders, E.A.B. Faculty Civil Engineering and Geosciences Department Structural Engineering Date 2012-04-11 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. Subject cryogenic suctionfrost expansionGibbs-free energysalt frost attack To reference this document use: http://resolver.tudelft.nl/uuid:ebc6e80e-3c9e-46a5-80be-c729524dd4f4 Publisher RILEM Publications ISBN 978-2-35158-129-2 Source Second International Conference on Microstructural-related Durability of Cementitious Composites, RILEM Proceedings pro083, 11-13 April, 2012, Amsterdam, The Netherlands Part of collection Institutional Repository Document type conference paper Rights (c) 2012 The Author(s) Files PDF 284510.pdf 404.32 KB Close viewer /islandora/object/uuid:ebc6e80e-3c9e-46a5-80be-c729524dd4f4/datastream/OBJ/view