The effect of superficial hydrophobic treatments to increase the frost durability of concrete evaluated by means of acoustic emission and CDF test

Miriana Vadalà , Institute for Materials Science and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Essen, Germany
A. Mobili , Department of Materials, Environmental Sciences and Urban Planning, Università Politecnica delle Marche, Ancona , Italy
F. Tittarelli , Institute of Atmospheric Sciences and Climate, National Research Council , Bologna, Italy
Doru Lupascu , Institute for Materials Science and Center for Nanointegration Duisburg-Essen (CENIDE), University of Dui, Essen, Germany

Reinforced concrete structures (RCS) exposed to freezing phenomena in the presence of de-icing salts are known to be subjected to the corrosion of embedded reinforcements. The penetration of aggressive substances inside concrete is related to water suction through capillary action. In order to slow down this action, concrete surface can be treated by applying hydrophobic solutions in the admixture or onto the surface. The superficial layer which is formed can modify the water contact angle and hence hinder the water penetration.

This research work is focused on the durability of concrete with or without hydrophobic treatments, and exposed to freeze-thaw cycles. Four different concrete mixtures were prepared at the same aggregate/cement ratio by varying the water/binder ratios (0.50, 0.55, 0.60, 0.65). Specimens were studied in terms of mechanical and stability properties. Flexural and compressive strength tests and CDF-test after exposure of 28-days cured concrete specimens in presence of de-icing salts were performed. Acoustic emission measurements are still going on. Results obtained highlight that the application of the surface treatment with hydrophobic admixture is an important parameter for increasing the resistance of concrete to frost phenomena.

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