CORROSION OF GALVANISED AND UNGALVANISED COLD-FORMED STEEL IN CHLORIDE AND SULPHATE SOLUTIONS

The light steel framing is widely use around the world to replace the conventional construction method. However, there are some factors that affect the corrosion rate of the steel framing structures. The factors are oxygen, humidity, sulphate, chloride and copper sulphate which highly contain in seawater regions or specifically coastal area. Hence, all these factors that influence the corrosion rate of the steel framing shall be study to determine the service life and the maintenance required throughout their service life. This paper studies the effect of the chloride, sulphate and the rainwater to the light steel framing structure and the corrosion resistance that provided by the zinc coating on the surface of the steel. The galvanized steel and ungalvanized steel are immersed in different concentration of sodium chloride and copper sulphate solutions for 28 days. The corrosion rate is obtained by measured the weight loss of the steel coupons in the interval 7-days of the immersion time. Other than that, the corrosion rate in seawater is analysed by the result of 0.5 Mol of NaCl and 0.016 Mol of CuSO4. The corrosion rate for the NaCl and CuSO4 is much higher than the corrosion rate in the rainwater. The corrosion resistance that provided by the zinc coating is extremely higher compared to the steel that without the protection. Prediction equation of metal loss from experimental study is proposed for a reliable light steel structure in a function of time.