March 20, 2014
In many parts of the world coastlines require improved fortifications against bad weather damage. One example is the three kilometre sea defence wall constructed by Birse Coastal in the popular seaside town of Blackpool on the north west coast of England. Nickel-containing stainless steel played an integral role.
The wall consists of revetments, a series of steps which are designed to break up waves as they come inshore. Behind this, a shaped wave wall curls and pushes incoming waves back into the sea. As this is a busy beach area, it was important to come up with an accessible and aesthetically pleasing design, where people could sit on the revetments at low tide and use the wave wall as a
wind break. A dye was added to the concrete to create a warmer colour in harmony with the seaside environment.
Over a five year period, 720 wave wall units, along with revetments were produced, using over 1000 tonnes of stainless steel in the form of 340,000 cut and bent pieces, ranging in diameter from 6mm to 32mm. The units were pre-cast close to the site and then brought to the beach.
Stainless steel was selected for the areas of the structure most exposed to seawater, with normal carbon steel rebar used for the more deeply embedded areas. This created a cost effective design with less concrete cover, but still retaining a long life expectancy for the structures, with low on-going maintenance costs. Grade 1.4301 (Type 304, UNS S30400) stainless steel was used, produced to the BS 6744 standard.
As well as protecting Blackpool from flood damage, the wave wall has enhanced the appearance of the whole beach area.