Water Transport and Permeability Coefficient Calculation for Unsaturated Cement-Based Materials Based on X-CT

Abstract

Abstract: The technique of X-CT combined with Cs ion enhancing was used to detect the movement of water transport in unsaturated cement-based materials. From that, the relationship between the distance of water uptake and exposed time was established, and the capillary coefficient was obtained. What’s more, a theoretical model for calculating the intrinsic permeability coefficient based on capillary coefficient and pore structure was provided. Effects of water to cement ratio, fly ash content, ground granulated blast furnace slag content and volume fraction of sand on the capillary coefficient and intrinsic permeability coefficient were investigated systematically. The results show that the capillary coefficient increases from 2.07×10^-4 m/s^1/2 to 3.22×10^-4 m/s^1/2 with the water to cement ratio increasing from 0.35 to 0.55, and the intrinsic permeability coefficient increases by one order of magnitude. The addition of fly ash effectively decreases the property of water transport in cement paste, and the ideal content is 30% (mass fraction). The intrinsic permeability coefficient of cement paste with 30% (mass fraction) ground granulated blast furnace slag is one order of magnitude higher than that with 30% (mass fraction) fly ash. For water transport in mortars, both of the capillary coefficient and intrinsic permeability coefficient decrease with the sand volume fraction increasing from 0% to 40%. It also concludes that the ITZ of mortar connect completely when the volume fraction of sand comes up to 42.4%.

Key words: X-CT, cement-based material, durability, water absorption property

CLC Number:

TU528

YANG Lin, ZHANG Yunsheng, ZHANG Chunxiao. Water Transport and Permeability Coefficient Calculation for Unsaturated Cement-Based Materials Based on X-CT[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2020, 39(12): 3775-3782.

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