Hydrophobic Admixtures to Control Corrosion of Galvanized Steel Reinforcement in Concrete

The influence of silane-based hydrophobic agents, added to concrete as chemical admixtures, on the corrosion resistance of galvanized steel reinforcement embedded in concrete was studied. Sound or deliberately pre- cracked concrete specimens, with 0.5 or 1 mm wide crack, were manufactured with w/c of 0.45 and 0.75, both in the presence and in the absence of a silane admixture. The specimens were exposed to wet-dry cycles in a 10% NaCl aqueous solution. The results, in terms of electrochemical measurements, as well as visual and metallographic observations carried out on the galvanized steel reinforcement removed from the specimens, showed that the hydrophobic concrete is able to protect galvanized steel reinforcement from corrosion even in the presence of cracks in the concrete cover, especially when a high w/c is used.