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Hygrothermal Properties of Mortar Layers: Implications for Freeze-Thaw Damage in Brick Walls
During the freezing process, the expansion of moisture within the building material leads to increased pressure and may result in cracking and delamination of the material. The phenomenon of freeze-thaw damage to brick walls poses a significant threat to the value and performance of masonry heritage buildings. Brick wall is a masonry composed of sintered brick and mortar, and the differences in the moisture transport properties and icing characteristics of the two materials make the temperature and moisture distribution of the brick wall during the freeze-thaw process very complex.
This study proposes a gas-liquid-solid three-phase equilibrium heat and moisture coupling transfer model to simulate the process of continuous freezing of three types of wall surfaces, namely, pure bricks, lime-mortar brick walls and cement-mortar brick walls, after absorbing water for a certain period. We found that mortar significantly impacts the wall’s freeze-thaw cycle, with different effects at various stages. Initially, as the wall absorbs external moisture, the mortar layer blocks this moisture from reaching the bricks, increasing icing on the mortar’s exterior. Lime mortar, being more porous, initially reduces ice formation inside (warm side) by absorbing more water. However, as freezing progresses, it prevents water from moving from the warm to the cold side, leading to interior icing. In contrast, cement mortar’s influence diminishes in the stabilization phase, while lime mortar’s greater porosity continues to reduce icing on the exterior by retaining more moisture.
Hygrothermal Properties of Mortar Layers: Implications for Freeze-Thaw Damage in Brick Walls
During the freezing process, the expansion of moisture within the building material leads to increased pressure and may result in cracking and delamination of the material. The phenomenon of freeze-thaw damage to brick walls poses a significant threat to the value and performance of masonry heritage buildings. Brick wall is a masonry composed of sintered brick and mortar, and the differences in the moisture transport properties and icing characteristics of the two materials make the temperature and moisture distribution of the brick wall during the freeze-thaw process very complex.
This study proposes a gas-liquid-solid three-phase equilibrium heat and moisture coupling transfer model to simulate the process of continuous freezing of three types of wall surfaces, namely, pure bricks, lime-mortar brick walls and cement-mortar brick walls, after absorbing water for a certain period. We found that mortar significantly impacts the wall’s freeze-thaw cycle, with different effects at various stages. Initially, as the wall absorbs external moisture, the mortar layer blocks this moisture from reaching the bricks, increasing icing on the mortar’s exterior. Lime mortar, being more porous, initially reduces ice formation inside (warm side) by absorbing more water. However, as freezing progresses, it prevents water from moving from the warm to the cold side, leading to interior icing. In contrast, cement mortar’s influence diminishes in the stabilization phase, while lime mortar’s greater porosity continues to reduce icing on the exterior by retaining more moisture.
Hygrothermal Properties of Mortar Layers: Implications for Freeze-Thaw Damage in Brick Walls
Lecture Notes in Civil Engineering
Berardi, Umberto (editor) / Xie, Huarong (author) / Huo, Lei (author) / Li, Yanan (author) / Xia, Changchang (author) / Li, Yonghui (author) / Hokoi, Shuichi (author)
International Association of Building Physics ; 2024 ; Toronto, ON, Canada
2024-12-14
7 pages
Article/Chapter (Book)
Electronic Resource
English
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