Long-term 20-year performance of surface coating repairs applied to façades of reinforced concrete buildings

Abstract

The present study was conducted to evaluate effectiveness of surface coating repairs after 20 years since their application on façade panels of two existing concrete buildings. The repairs involved coatings and electrochemical treatment systems comprising Silane and Siloxane (S/S), Amino Alcohol Corrosion Inhibitor (AACI), acrylic coating, and re-alkalisation (Re-Alk). Altogether, 11 selected façade panels were evaluated in this study. The field investigations comprised visual survey, non-destructive tests (NDT) for compressive strength using Schmidt hammer, cover depth, reinforcement bar size, Ultrasonic Pulse Velocity Test (UPV), Torrent permeability. Limited carbonation depth tests were also conducted on selected panels. It was found that, UPV and permeability values indicated poor or very poor concrete quality in the repaired panels except for those repaired using acrylic coatings, which showed retention of good concrete quality. AACI coatings with or without S/S gave similar performance as control, implying no significantly improved protection by these repair materials.

Keywords

• Corrosion
• Carbonation
• Repair coatings
• Silane and siloxane
• Corrosion inhibitor
• Acrylic sealant
• Re-alkalisation
• Non-destructive tests
• Visual survey