Corrosion Behavior of Hot-Dip Al Coating Contact with Concrete During Hardening Process of Concrete

Hot-dip Al coating is an effective and economical protection method for steel structures. Hot-dip Al coated steel members have also been used in the case that contact with concrete. Al is an amphoteric metal that can react with acid and alkaline. Concrete is an alkaline material. The corrosion behavior of hot-dip Al coating contact with concrete is studied by measurement OCP and monitoring the change of pH during the hardening process of concrete. And the atmospheric test that simulates the actual structures. The corrosion products are analyzed by the diffraction of X-rays (XRD). The hot-dip Al coating can be dissolved during the hardening process. With the decreasing pH of concrete, the Al coating also has a relatively stable due to the passivation effect. In the dry and no stagnant water environment, the hot-dip Al coating has a better anti-corrosion behavior due to the passivation and shielding effect of complex calcium-aluminum compounds.