PRECAST CONSTRUCTION SYSTEMS

Precast concrete elements are increasingly used for maritime structures as they offer efficient unit production and rapid construction. Precast elements can be of many forms to construct a variety of maritime structures:-

Precast Elements
• Solid concrete blocks
• Hollow concrete blocks
• Open topped caissons
• Open base ‘shell’ caissons
• Immersed tubes
• Bridge pier bases
• Mast bases
• Other – purpose made

Maritime Structures
• Harbour, quay and seawalls
• Bridges
• Breakwaters
• Immersed tube tunnels
• Barrages
• Wind turbine mast bases
• Other maritime structures

Open topped caissons and immersed tube elements are normally floated into place taking advantage of their natural buoyancy, before being lowered into place. Blocks and open base ‘shell’ caissons can be lifted in by cranes.

Plain precast blocks are typically unreinforced giving advantages of increased longevity. Due to the generally aggressive exposure conditions of maritime works, reinforced concrete elements are often formed with a combination of protected reinforcement, increased cover and corrosion resistant concrete. This is particularly so in more extreme climates. Precasting often enhances quality control, allows economic repetitive production and a reduction of insitu marine works to a minimum. The elements can be used singularly, joined, stacked and arranged to form efficient and varied structures.

An outline of the development process for precast construction systems is shown in Marine Construction Systems and grout bag foundation and jointing systems are shown within Foundations to Precast Structures and Joints, Seals and Bearings