Building infrastructure to last is becoming increasingly topical as cities and countries are burdened with the high costs of maintaining things like hospitals and highways, some of which are not even that old but were built with materials not suited for the intensity of use, the geography, or other factors.
For bridges, in particular, the use of carbon steel rebar has led to the deterioration of concrete over time. The worst corrosion occurs in regions where road salt is heavily used or in areas near to salt water, but nickel-containing stainless steel rebar prevents damage to structures caused by rebar corrosion. Stainless steel rebar is used in ever increasing amounts today both in North America and around the world. While stainless steel is more expensive, its selective use can be justified financially when all the costs of maintaining the structure over its life are considered.
In Edmonton, the provincial capital of Alberta, Canada (about 30kms southwest of Sherritt’s Fort Site), with a metropolitan population of over one million, a new ring road around the city was completed in 2016, with the Northeast Anthony Henday Drive portion being 27km of 6 or 8 lane highway. Winter is especially hard on the roads in Edmonton. The average daily temperature in January is -10.4°C, with an annual snowfall of about 124cm. Large amounts of salt, both sodium and the more corrosive calcium chloride, are applied to keep the roads as free from ice as possible. In 2011, Type 2304 (S32304) stainless steel was specified for a trial for one highway interchange on the ring road. The success of that venture led to the specification of Type 2304 rebar for a major portion of this new section, reported to be in the region of 6,000 tonnes. Perhaps in 75 years or so, a Life Cycle Assessment will be done of one of these Edmonton bridges, leaving no doubt that the engineers in charge made the right decision.