There are numerous benefits to hot-dip galvanizing steel bridge structures, but chief among them are durability and maintenance-free longevity. Hot-dip galvanizing is the process of immersing fabricated steel into a bath (kettle) of molten zinc. While in the galvanizing bath, the iron in the steel reacts with the zinc in the kettle to form a series of intermetallic layers, which are harder than the base steel. These tightly-bonded layers provide hot-dip galvanized steel with incredible abrasion resistance and durability.
Additionally, the intermetallic layers grow perpendicular to all surfaces of the steel, which means corners and edges have as much protection as flat surfaces, and all interior surfaces are also coated. The uniform, complete coverage ensures no areas of weakness for corrosion to begin, which leads to a long, maintenance-free life.
The durability and longevity of hot-dip galvanized steel will be on display for generations in projects such as the Churchill River Bridge in Goose Bay, Labrador, Newfoundland, Canada. The bridge was constructed in 2006 with more than 400 feet in three spans, making it the largest bridge in the Trans Labrador Highway. It required 2,000 tons of galvanized steel. The Bailey style, cantilever bridge was assembled on land and pulled over the river with special purpose machinery. Hot-dip galvanized steel can withstand not only the abrasiveness of this installation technique, but also the harsh environment of the Northern climate, where the construction and maintenance season is limited to only three months. Thanks to hot-dip galvanizing, the Churchill River Bridge will complement the natural environment and surroundings while providing effective, maintenance-free corrosion protection for decades to come.
Note: This blog was submitted by Melissa Lindsley at the American Galvanizers Association.
Steel is a principal construction material in the bridge market due to its unmatched strength-to-weight ratio.