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Physico-mécanique des matériaux cimentaires soumis au gel-dégel

Abstract : Frost defacement of buildings, and bridges costs hundreds millions of Euros to Europe every year. Hence, undertaking better prediction and prevention of frost damage will be beneficial to civil engineering.
Frost damage is a combination of internal micro-cracks and scaling (bits of material peeling away of the surface down to a depth of some millimetres). The latter is enhanced by de-icer salts used to keep roads and highways good practicability.
Most of the physico-chemical mechanisms leading to frost damage are well known. However it still lacks a holistic physically-based quantitative assessment of the stress and strain fields in porous materials submitted to freezing-thawing cycles with salts.
To cope with this difficulty, both experimental and theoretical approaches are conducted. Experimental studies aim at improving the quantification of amount of ice formed within a partially frozen porous medium. Indeed this relation is found to be sufficient to characterize the material state at the macroscopic scale in case of a reversible evolution.
The measurement was performed through a novel experimental device based on capacitive method. This technique relies upon the dielectric properties of liquid water, ice, air, and mineral substrate in the radio-frequency range. A semi-empirical method based upon the Lichtenecker model and combining drying and freezing tests, provides an accurate estimation of the liquid water content versus the temperature in freezing cement pastes. This estimation is further analysed with the help of thermoporometry concepts in order to characterize the pore size distribution and the specific surface area. The results range in the same order of magnitude as those assessed from gravimetric sorption/desorption isotherms.
Such information allowed predicting the material thermo-mechanical behaviour through poromechanics. Then the occurrence of surface scaling without de-icing salts was proofed and explained while the effect of air-voids on the frost resistance of a porous structure is quantified.
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Submitted on : Tuesday, April 29, 2008 - 2:07:13 PM
Last modification on : Thursday, January 11, 2018 - 6:15:13 AM
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  • HAL Id : tel-00276334, version 1

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Antonin Fabbri. Physico-mécanique des matériaux cimentaires soumis au gel-dégel. Mécanique [physics.med-ph]. Université de Marne la Vallée, 2006. Français. ⟨tel-00276334⟩

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