Marine and coastal
Concretes designed to meet the appropriate requirements of EN 206-1 and BS 8500 perform well in the harsh environmental conditions experienced in marine and coastal applications. Both in-situ and precast concrete are used in a wide range of applications along the coast. In ports and harbours, concrete often forms the main structural body of quays, used in caissons, blockwork or diaphragm wall structures. Whatever form of substructure construction is used, concrete is invariably used for the quay deck.
Coastal defence walls
The speed with which precast concrete sea defence walls can be erected makes the material particularly suited to construction in a tidal environment. In addition, the outstanding durability and aesthetic quality of factory-produced elements adds to their suitability for marine environments.
Revetments are structures placed on banks in such a way as to absorb the energy of incoming waves. They are normally found on internal waterways but can also be used to protect the shoreline. They may be either watertight, covering the slope completely, or porous, to allow water to filter through after the wave energy has been dissipated. Precast concrete can be used as individual blocks or mats.
Specially-designed box culverts with increased cover to reinforcement and effective crack control provide the durability to resist the most extreme conditions and are, therefore, ideal for this type of application.
Tetrapods, tribars and dolos
Various forms of precast concrete armour blocks can be used to protect harbour walls, headlands, breakwaters and other vulnerable areas from the force of the sea. Precast concrete can be an economic alternative to large blocks of armourstone, a material which invariably needs importing into the UK. By contrast, precast concrete is generally manufactured on, or close to, the site, reducing the environmental impacts of transportation and supporting the local economy. When armourstone is used, randomly or regularly placed specialist precast concrete elements often provide the primary armouring, since large stones alone may be inadequate or inefficient in resisting the action of the sea.
The use of specialist admixtures in conjunction with good mix design allows in-situ concrete to be placed underwater. The mixes are designed to minimise washout and can be used in either fresh or salt water.