Definition - What does Ponding mean?
Ponding is an occurrence where water accumulates in low-lying areas on a roof, metal surface or concrete surface. Ponding leads to higher concentrations of electrolytes and ions that react to cause corrosion and rust.
Ponding may also refer to purposely wetting the surface of a freshly poured concrete slab by installing a temporary containment around the concrete in order to facilitate the curing process.
Corrosionpedia explains Ponding
High moisture levels due to ponding accounts for increased rusting. Rusting of a metal's surface occurs more rapidly in moist conditions and less so in a dry environment. The presence of salt in the environment also has a direct correlation to the rate of corrosion experienced by a metal; the greater the salt concentration, the greater the rate of corrosion.
Ponding also facilitates specific kinds of corrosion such as pitting and crevice corrosion due to its localized presence in a confined area. This in turn can have a severe impact on the structural integrity of the metal as prolonged corrosion leads to weakened support and firmness.