Bridges

In most cases, bridges are a significant investment and also span roads, railways or rivers making maintenance of the steel structure costly in time and money. For this reason, a high performance, proven corrosion protection coating is often required and specified. Bridges and bridge steelwork is also very large and hence metal spraying is an ideal solution.

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.

In the UK, the Highways Agency and Network Rail have thermal spray coatings in their specifications and these are commonly applied to road, rail, waterway and footbridges. One of the most iconic projects in the UK that was zinc sprayed by Metallisation was the Forth Road Bridge opened in 1964 – at the time the longest suspension bridge outside of the USA at 2,512m. Many hundreds of bridges have been coated since then on all continents.

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 case studies and examples following are just a small summary of the number and type of bridge structures that have been sprayed.