Precast concrete is a form of concrete prepared for casting, cast in a reusable mould and cured in a controlled environment away from its final destination.
Precast concrete units may travel a few metres when precasting on-site, or thousands of kilometres when the components are manufactured on a different continent.
Precast concrete elements can be joined together to build a complete structure. There are two types of connections:
Precast concrete is used to build all kinds of products (e.g., traffic barriers, sewage pipes, retaining walls) and structures (residential buildings, bridges, railway stations).
The history of the modern-day precast concrete industry began in the 1900s when John Alexander Brodie, an English civil engineer, discovered that precast concrete components could be joined together to build structures efficiently. He was the first to get a patent (no. 6,115), in 1901, for the process of creating precast concrete panelled buildings.
That same year Brodie started 18 months of trials in Cobbs Quarry, Everton. Casting concrete in vertical steel moulds, he built a prototype cottage in 1903 based on the patent drawings.
In 1905 Brodie built the first precast concrete tenements in Eldon Street (Liverpool): a three-story 12-apartment block of flats (demolished in December 1964).
He also exhibited a precast concrete cottage at the 1905 Cheap Cottages Exhibition in Letchworth Garden City. Now it is a Grade II* listed building located at 158 Wilbury Road, SG6 4JD.
In 1906 he built the corporation stables at Walton (demolished in 2002).
Brodie’s work influenced Grosvenor Atterbury, a New York architect who developed in 1908 a system of construction based on hollow-cored, precast concrete units with story-height wall panels. The components were factory-made and, like Brodie’s, transported to the site and hoisted into position by crane.
Atterbury built the houses at Forest Hills Gardens (New York City) with precast concrete panels between 1910 and 1918.
Precast concrete beams can be reinforced with steel reinforcement and prestressed with steel strands. They may work compositely with the floor or the columns.
Beam profiles are usually inverted T-beams or L-beams to support a precast concrete slab.
Precast columns are usually square, rectangular or circular, although other shapes are possible. It is good practice to apply 50 mm increments to the columns’ sides (or diameter).
Circular columns are typically cast vertically, reaching one-storey height. Square and rectangular columns can be cast horizontally, allowing heights up to 24 m.
The columns can have corbels or structural inserts to provide support for beams.
Precast concrete walls are used to build strong, durable and fire-resistant structures.
Crosswall is the most common form, where the panels can form structural load-bearing partition walls, external walls and floor slabs.
Precast concrete cladding provides low-maintenance facades. The panels can include windows and insulations to reduce construction time on site. They are divided into structurally load bearing and non-loadbearing.
Load bearing cladding systems have an inner structural panel, an insulation layer and an outer non-structural panel. The most common type is sandwich panels.
Non-loadbearing cladding systems, like the single-leaf precast cladding, have no structural function. They provide the required architectural finish to the building, along with a weather barrier.
Hollow core slabs have voids throughout the component. The cores help reduce the slab’s self-weight, optimise the structural capacity, and provide room for service ducts.
Units are available in standard 1200 mm widths and depths from 110 mm to 400 mm. Other dimensions can be fabricated when required.
Double-tee floor units are ribbed precast prestressed concrete units. Depths between 300 mm and 800 mm are common. Higher depths are also available if needed.
Double-tee floor units are produced in standard widths of 2400 mm. They offer greater structural capacity at longer spans than hollow cores.
Precast concrete components may require on-site repairs to satisfy the original requirements of the material. The most common repair methods are:
Patches replace damaged or deteriorated concrete with a cementitious material. They may be structural (for load transfer) or cosmetic (for visual appearance).
Not all cracks on precast concrete components require repair. A low-viscosity epoxy is a good solution to repair cracks. It can be installed by gravity flow or pressure injection. The cracks should be cleaned before performing the repair.
The connections may require repair if the components are misplaced or damaged or the embedment is missing.
Structural calculations are needed before choosing a repair method. Some available solutions are: increasing the dimensions of the connection material, installing a new connection close to the original, or adding stiffeners to the connection.
Precast concrete elements usually require little maintenance except when subjected to harsh conditions, in which case they should be inspected periodically to detect and prevent long-term maintenance issues.
The Lansdowne, Birmingham
Burlington Gate, London
Police Federation of England and Wales HQ, Leatherhead
Kings Cross P2, London
11 Baker St, London
Ramada Encore Hotel, Warrington
Marriott Hotel, Manchester
Motel One and Staycity Aparthotel, Manchester
Crown Woods School, Greenwich
Bishop of Rochester Academy
National School of Ballet, London
Victoria and Albert Museum Dundee
Poole Multi-Storey Car Park
Wakefield Multi Storey Car Park
N22 Bridges over the Sullane and Laney Rivers, Macroom
Plymouth Road Bridge, Blackpool
Twickenham Station Development, London
London Bridge Station, London
Farringdon Station, London
Kia Oval County Cricket Stadium, London
Olympic Copper Box Arena, London
Precast concrete allows you to build faster, safer and save costs. However, the process of casting and demoulding is critical to meet the project deadline.
If you demould too soon, the elements won't be ready, and you must cast new units. This could delay the whole project.
If you demould too late, the precast concrete will be stronger, but you are throwing time away.
ConcreteDNA Precast allows you to demould sooner without losing quality:
Speak to sales to save time and money on your project.
Elliott, Kim S.: Precast concrete structures. Boca Raton (FL), CRC Press, 2018.
Manual for fabrication of precast prestressed concrete products. Springfield, Illinois Department of Transportation, 2020.
Moore, Richard: “An early system of large-panel building”, RIBA Journal, vol. 76, 1969, pp. 383-386.
Offsite concrete construction: The solutions. MPA The Concrete Centre, 2018
Offsite concrete construction: A guide to the design and construction of precast concrete in buildings. MPA The Concrete Centre, 2019.
PCI design handbook: precast and prestressed concrete, 8th Edition. Chicago, Precast/Prestressed Concrete Institute, 2017.
“Precast concrete”, Designing Buildings, Designing Buildings Ltd, https://www.designingbuildings.co.uk/wiki/Precast_concrete [Accessed on 22 January 2023]
Everything you need to know about precast concrete: What it is, how it’s made, what you can build, benefits and disadvantages.
If you expect low temperatures during your next concrete pour, you must plan and ensure all materials, workforce and equipment are on-site and ready before pouring concrete.