The most commonly used metals are iron and steel, usually selected for their strength, ease of fabrication, and cost. These metals corrode in most outdoor atmospheres. Steel corrosion is a process that requires simultaneous presence of moisture and oxygen. The rate in which the corrosion process progresses, depends on the “micro-climate’ surrounding the structure. Corrosion depends on the total time during which the surface is wet, due to rainfall and condensation. The electrochemical process oxidizes the steel, producing iron oxide, known as rust. Unprotected steel in dry environments, like inside of buildings, corrosion will be minimal due to the lack of water contact.
Rusted iron and steel can occupy six times the volume of the original metal material. These expansive forces can cause concrete around the rebar or steel beams, to crack or delaminate, spall and break off. A spall is defined as flakes of material that are broken off a larger solid body. Delamination and concrete spalling increase the access of air and water getting to the reinforcing steel. This cycle of corrosion decreases the concrete and steals ability to safely carry imposed loads. Increased maintenance, higher maintenance cost and decreased service life of the structure is an effect of spalling and delamination. This process can effect foundations, cement bridges, retaining walls, and sea walls.
In coastal regions like Florida, saltwater and metal do not mix. The combination of moisture, oxygen and salt, especially sodium chloride, damages metal worse than rust does. Structures fall apart due to the corrosion eating away the material, weakening the structure. Humid ocean air, like Florida’s can cause metal to corrode 10 times faster than air with normal humidity. The salt and bacteria in ocean water will corrode metal five times faster than fresh water.
A form of corrosion is electrochemical corrosion, occurring when saltwater interacts with metal. Saltwater contain ions and conducts electricity, attracting ions from other compounds to help attack the metal ions. When metal is exposed to saltwater for an extended period, anaerobic corrosion forms leaving sulfate deposits surrounding the submerged metal. Hydrogen sulfide is produced, while at the same time bacteria grows in the saltwater, teaming up with these ions and sulfates to attack the metal from all angels.
Foundation Masters LLC, is the number one structural expert in Florida, specializing in Steel Corrosion repair.
Please feel free to call our office and ask any questions related to your structural issues. Call today for your free home inspection.