When exposed to the atmosphere, all metals have the natural tendency to revert to the lesser energy state of ore. In simple terms, this natural phenomenon is corrosion, and is most commonly seen as iron ore or rust. Steel is an excellent building material – it is readily available, fully recyclable and has a high strength-to-weight ratio, low environmental impact, and long-term durability. However, it is inevitable steel corrodes.
Though corrosion may be more visible, all building materials (concrete, plastic, wood, etc.) diminish and decay over time. Steel is just more honest and transparent – alerting you to any problem areas rather than hiding them until it is too late. One catastrophic issue event due to unknown issues can be extremely costly – monetarily as well as in loss of lives. Therefore, the answer to steel corrosion is NOT to use other building materials, rather to adequately protect exposed steel to minimize and delay the process with a coating such as hot-dip galvanizing.
Metallic corrosion is costly; nearly $423 Billion annually in the US, and about one third of that is noted as avoidable corrosion; thus, that cost could be eliminated if proper corrosion protection methods were in place. Unfortunately, one of the biggest corrosion offenders is public infrastructure which means we all pay (taxes) for the lack of adequate planning. The long-held attitude in public construction of cheapest bid wins has been proven flawed. Building with the cheapest method initially often means greater costs in the future – costs public budgets rarely account for nor have the means to consume.
However, the cost of corrosion is not just financial. Beyond the huge direct outlay of funds to repair and/or replace corroded and/or decaying structures are the indirect costs (natural resources, potential hazards, and lost opportunity). When a project is constructed with a building material not able to survive its environment for the length of the design life, natural resources are needlessly consumed to continually repair and maintain the structure. Wasting natural resources is a direct contradiction to the growing focus and desire for sustainable development to benefit future generations.
In addition to the waste of natural resources, building structures that cannot sustain their environment can lead to hazardous situations. Accidents caused by corroded structures can lead to huge safety concerns, loss of life, resources, and more. One failed pipeline, bridge collapse, or other catastrophe is one too many and leads to huge indirect costs (more traffic delays, loss of business, etc.) and public outcry. Depending on which market sector (industrial, infrastructure, commercial, etc.) is being considered, these indirect costs may be as high as five to ten times the direct cost.