Influence of Silane-Based Hydrophobic Admixture on Oxygen Diffusion Through Concrete Cement Matrix

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Title: Influence of Silane-Based Hydrophobic Admixture on Oxygen Diffusion Through Concrete Cement Matrix

Author(s): F. Tittarelli, G. Moriconi, and R. Fratesi

Publication: Special Publication

Volume: 195

Issue:

Appears on pages(s): 431-446

Keywords: admixture; cement (hydrophobic); concrete

Date: 7/1/2000

Abstract:
The oxygen diffusion coefficient through hydrophobic cement-based materials fully immersed in water was determined by potentiostatic measurements on concrete and by the use of a diffusion cell on cement pastes and mortars. The results obtained show that very high oxygen diffusion occurs through cement paste, mortar and concrete made with hydrophobic admixture as opposed to negligible diffusion through the reference cement matrix without admixture. Moreover, the oxygen diffusion coefficients measured through hydrophobic cement matrices immersed in water were comparable with those reported in literature for unsaturated cement materials in air. These experimental results appear to confirm that oxygen dissolved in water directly diffuses as a gaseous phase through the empty pores of a hydrophobic cement matrix. This could explain the severe corrosion of steel reinforcement embedded in cracked hydrophobic concrete immersed in an aqueous chloride solution observed in a previous work.