Water transport in air-pores
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Texte, Inc, Tokyo, Japan
Publication date: 2011-12-01
Corresponding author
Shinsaku Tada
Cement Wapno Beton (Special 2011 16) 60-65 (2011)
Water transport experiments were performed on AAC with known pore structure and well-controlled moisture content. Specimens with the critical moisture content for freeze/thaw resistance were observed with the cryo-SEM. Evidences were confi rmed that the ice segregated on the surface of air-pores as a result of redistribution of unfrozen water coming from the matrix part between air-pores. The standpipe absorptivity test for specimens with an air-pore volume of approx. 45 vol.% while having different mean air-pores diameters showed an abrupt jump of permeability when the mean air-pores diameter was smaller than 0.15 mm or the air-pores connectivity was 20%. In the free water uptake test using a dried AAC specimen, the capillary suction precedes other water transports and saturates the capillaries of 35 vol. % instantly followed by a slow absorption process, i.e. escaping of entrapped air bubbles that controls the subsequent absorption rate.
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