Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
A mechanism of frost damage of concrete under supercooling
It is the purpose of this paper to describe a frost damage mechanism of concrete numerically. A mechanism considering freezing of water under supercooling is pro-posed. Freezing of capillary water is the origin of frost damage. It depends on super-cooling and depression of melting point. When water under supercooling freezes, ice crystal grows very rapidly and the volume increases about 9%. It causes a rapid flow through the capillary pore toward the air void. Consequently viscosity of unfrozen water produces high hydraulic pressure. The relation between hydraulic pressure, flux, the air void system and the pore structure is described by Poiseulle's equation on viscous fluid. When hydraulic pressure goes beyond the tensile strength of hard-ened cement paste, a micro-crack must occur. Subsequent growth of ice crystals clearly increases the plastic deformation. The cumulative plastic deformation is observed as a phenomenon of frost damage. The relation between the durability factor (ASTM C 666 A) and plastic deformation is verified experimentally.
A mechanism of frost damage of concrete under supercooling
It is the purpose of this paper to describe a frost damage mechanism of concrete numerically. A mechanism considering freezing of water under supercooling is pro-posed. Freezing of capillary water is the origin of frost damage. It depends on super-cooling and depression of melting point. When water under supercooling freezes, ice crystal grows very rapidly and the volume increases about 9%. It causes a rapid flow through the capillary pore toward the air void. Consequently viscosity of unfrozen water produces high hydraulic pressure. The relation between hydraulic pressure, flux, the air void system and the pore structure is described by Poiseulle's equation on viscous fluid. When hydraulic pressure goes beyond the tensile strength of hard-ened cement paste, a micro-crack must occur. Subsequent growth of ice crystals clearly increases the plastic deformation. The cumulative plastic deformation is observed as a phenomenon of frost damage. The relation between the durability factor (ASTM C 666 A) and plastic deformation is verified experimentally.
A mechanism of frost damage of concrete under supercooling
Katsura, O. (Autor:in) / Kamada, E. (Autor:in)
1997
10 Seiten, 15 Bilder, 7 Quellen
Aufsatz (Konferenz)
Englisch
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