The corrosion of the zinc layer on buildings is related to the properties of the building materials. For example, cement and lime mortar have high alkalinity, which is highly corrosive to the zinc layer. Additionally, during the drying process, the evaporating moisture condenses on the surface of the zinc layer, allowing oxygen to penetrate but preventing carbon dioxide from reaching it, leading to intense corrosion. If the cement contains magnesium chloride, the chloride can damage the protective film and accelerate the corrosion of the zinc layer. Asphalt applied to rooftops can produce organic acids under sunlight, which, when in contact with the zinc layer through rainwater, exerts a strong corrosive effect.
Galvanized steel pipes used for transporting warm water and steam are typically wrapped in insulation materials. If the moisture in these materials is not easily evaporated, it can lead to corrosion. For instance, when slag wool is used as insulation, it not only contains a certain amount of moisture but also sulfides, which further accelerates the corrosion rate of the zinc layer.
