An Xbloc is an interlocking concrete block (or “armour unit”) designed to protect shores, harbour walls, seawalls, breakwaters and other coastal structures from the direct impact of incoming waves. The Xbloc model has been designed and developed by Delta Marine Consultants since 2001 and has been subjected to extensive research by several universities.
Concrete armour units are generally applied in breakwaters and shore protections. The units are placed in a single layer as the outer layer of the coastal structure. This layer is called the armour layer. Its function is twofold: first, to protect the finer material below it against severe wave action; second, to dissipate the wave energy to reduce the wave run-up, overtopping and reflection. These functions require a heavy, but porous armour.
Common factors to apply single layer concrete armour units are:
- natural rock is unavailable in required size or quality to withstand design wave or current loads
- quarry production is insufficient to match the material demand
- existing quarries are in uneconomic distance to project location
- road connections have load restrictions (bridges) and other bottlenecks, are in poor condition or congested
Also compared to older concrete armour units, as e.g. tetrapod which are normally placed in double layer as for rock protection, modern single layer armour units involve significantly less concrete. Therefore, less construction material (cement, gravel) is required, reducing costs and also the carbon footprint of coastal protection works.
Concrete blocks can be used for the same purpose. Like Xbloc, most of these blocks are commercial developments and patented. As such Xblocs are not produced by the patent holder, but are fabricated and installed by a contractor who in return pays a license fee. Such an agreement involves certain technical support activities to ensure the correct application of the protection system.