PROTECTION PROVIDED BY SURFACE TREATMENTS AGAINST CHLORIDE-INDUCED CORROSION

Corrosion of reinforcement bars due to chloride ingress is a well know n problem in reinforced concrete. Several methods have been adopted to protect reinforced concrete, and one of them is to provide added prot ection to the concrete surface in the form of surface treatments such as silanes and siloxanes. They react with the cement matrix and form a hydrophobic layer on the walls of the pores within the concrete. This protects the concrete from the ingress of water and water-born salts. Moisture is required for reaction of silanes and siloxanes with the h ydrated cement matrix. However, too much water in the pores of concret e will prevent the treatments from penetrating deeper into the pores. A study has been carried out to investigate the variation, due to the presence of moisture, on the effectiveness of the protection. It has b een found that irrespective of the moisture content at the time of app lication of treatment, silanes and siloxanes provided good protection against chloride ingress and corrosion of reinforcement bars. However, the depth of penetration and therefore the durability of the treatmen t is adversely affected when the concrete is near saturation.