Bridges are a significant investment and can span roads, railways or rivers, making maintenance of the steel structure costly in both time and money. For this reason, a high performance and proven corrosion protection coating is often required and specified. Bridge steelwork is very large making metal spraying an ideal solution as work can be completed on-site without the need to dismantle structures.
Around the world, thermal sprayed zinc (TSZ), thermal sprayed aluminium (TSA) or thermal spray zinc/aluminium (TSZA) coatings are commonly specified and applied to give a life to first maintenance of the coating in excess of 20 years. The choice of material often depends on the environmental conditions expected for the bridge structure or sometimes local familiarity with a given material.
As well as protection of steelwork, thermal spray coatings have also been applied onto concrete to give corrosion protection to the reinforcing bars within the concrete structure. This is commonly a repair method used to extend the life of a bridge suffering from rebar corrosion.
Thermal spray coatings are commonly applied by flame spray or arc spray methods onto both new and existing bridge structures. The flame and arc spray process has been used to protect bridges from the elements and road salts for decades, minimising maintenance and increase the life of the road and rail network.