Corrosion of Centrifuged Hot Dip Galvanized Pad Hooks Used in GFRC Panels

Abstract

Anchor elements and pad hooks are necessary components for securing GFRC panels to the main building structure, but they are vulnerable to corrosion when exposed to the atmosphere. This study evaluated the corrosion resistance of two centrifuged hot-dip pad hooks (designated A1 and B1) in a 5% (w/v) NaCl solution. The samples were subjected to a 20-day salt spray test and observed visually and through SEM-EDX for elemental composition. The thickness of the surface coating was measured before and after the salt spray test. The visual observation and SEM images indicate that the pad hook samples remained corrosion-free in the studied environment as the brownish iron oxides were not observed. The surface products were mainly Zn-rich corrosion products. The average thickness of samples A1 and B1 before the corrosion test was found to be 78.15 and 145.65 µm. After the corrosion test, the thickness increased to 100.98 and 191.74 µm for samples A1 and B1, respectively. The EDX results, however, revealed that both samples were corroded when exposed to the corrosive medium but B1 had a superior resistance than A1. It is therefore recommended to improve the production processes to focus on surface pre-treatment and Zn coating thickness for improved corrosion resistance.