An Xbloc is a patented concrete armour unit that has been developed by BAM for shore protection and breakwaters. BAM says that a structure built with Xblocs requires considerably less concrete than other armouring systems and that the units can be placed faster.
The Calais project involves building a 3.3km breakwater. It is the third Xbloc project that will be carried out with Bouygues, following projects in Reunion Island and in Dunkerque. The Calais project will involve Xblocs of 4m3, 6m3, 10m3, 12m3 and 14m3, which are the largest block sizes used so far. The large blocks are needed to protect the new breakwater, which will be built in a very exposed environment with extreme tidal currents and wave conditions. The largest blocks in the project have a height of 3.5m and are 33t each.
The design of the breakwater has been prepared by Arcadis and physical model tests are being carried out by DHI in Denmark in order to confirm the design. The production of roughly 110,000m3 of Xblocs will start this month and placement is expected to continue until 2018.