In a new application for tilt-up, a series of panels averaging 15t is being constructed by Tilt-up Construction Services (TCS) in Hull, as part of a new waste transfer station for Robin Concrete & Waste Disposal. The project includes a 48m by 28m 'shed' building within which waste is screened, and a series of external yards and bunkers for stockpiling segregated materials.
Tilt-up panels are being used throughout the 4,000m 2scheme, which is due to complete in April. Main contractor FJ Chalcroft believes there is considerable scope for tilt-up concrete to provide such structures in the emerging waste management industry.
Tilt-up construction involves site casting the concrete walls of a building on its floor slab or on a separate casting bed and then tilting or lifting them into position by crane. The result is rapid construction arising from a well planned process more akin to a factory production line, but retaining the flexibility of insitu concrete work.
This method of construction has been used for commercial, industrial, recreational and residential buildings in more than 150 countries including Ireland, France and Hungary. And in the US, more than 7,000 buildings are constructed this way every year.
For the Hull waste transfer station, 45 structural tilt-up concrete panels measuring on average 5.5m by 4.4m high, and 240mm thick have been cast horizontally for walls to the main building and bunker structures.
The site is compact, so TCS is 'stack-casting' the panels up to five high to save space. The panels are then edge-lifted into place by a 200t Demag mobile crane.
Apart from containing the waste material, the panels have to withstand significant impact loads from equipment, such as loader shovels.
Free standing retaining walls include a moment connection at their base, at the junction with 500mm by 3m wide deep strip foundations. Panels have been cast in two phases, using C40 concrete supplied by Robin Concrete.
As a result of the Hull contract, TCS has been approached by three other county councils interested in developing waste management centres. And the company has recently quoted for a broad range of projects including distribution centres, firewalls and schools.
According to Jonathan Harrison of TCS, the tilt-up method was chosen for the Hull project because of its speed of construction, durability and overall cost effectiveness.
He adds: 'The client originally saw tilt-up construction being used in Australia and was keen to use what he thought was an innovative technique in the UK.
'The practicality of tilt-up to work around the critical path for the primary steelwork and process machinery on a raised slab supported by tilt-up panels proved to be very competitive and enabled individual phases of the project to be scheduled to the client's satisfaction.'
RCC guide A comprehensive guide for tiltup is available from the RCC:
Tilt-up concrete buildings:
design and construction guide brings together UK and worldwide experience of tilt-up in one document suitable for the UK. Copies are available from the Concrete Bookshop on (01344) 725704.
Alternatively, information can be found on the Reinforced Concrete Council's website (www. rcc-info. org. uk); a video and a PowerPoint presentation are also available on CD.
The Tilt-up Interest Group has been formed to encourage the efficient and effective use of tilt-up concrete construction in the UK. Members include architects, clients, project managers, developers structural engineers, contractors and tilt-up specialists. New members are always welcome. Contact the RCC for further details.
International example of tilt-up can be found on the Tilt-up Concrete Association's website (www. tilt-up. org).
Jonathan Harrison of Tilt-up Construction Services can be contacted on (01386) 561965.
Contact: Dr Jacqui Glass, Reinforced Concrete Council, Century House, Telford Avenue, Crowthorne, Berks RG45 6YS.
Tel: (01344) 725758; Fax.(01344) 761214.
Why use tilt-up?
Short and long-term financial gains: Costs start at around £40m 2-£50/m 2.Insurance premiums can be reduced due to concrete's inherent fire resistance and security.
Flexible finishes and architectural expression:
A variety of aesthetic effects is easy to achieve. Grooves, texture and colour can be used creatively, while plain finished or painted panels create a more subtle effect.
Energy savings year round: Tilt-up can be insulated economically to give the required U values or better. A combination of concrete and insulation builds in useful 'thermal mass', which can reduce temperature fluctuations by up to 7degreesC.
Robust, easily sealed surfaces: Tilt-up is ideal for controlled environments such as hospitals and laboratories. The low number of joints means exceptional airtightness is achievable.
Significant sound and noise reduction: Buildings near roads or airports can benefit from the sound reduction properties of tilt-up concrete which can typically provide an index of 52dB. In addition, noisy processes within buildings are isolated easily.
Fire resistant walls: Tilt-up panels can be designed for up to four hours' fire resistance and are cost effective as fire separation/ compartment walls. A 160mm thick wall provides up to two hours' resistance, and offers a 50% cost saving over conventional methods.
Secure envelope: Used frequently for security walls and prisons, tilt-up panels are virtually impossible to penetrate. Protection against mechanical damage is a further benefit.
Fast programme to completion: This is a major reason for choosing tilt-up.
Materials are procured easily and the typical elapsed time from casting panels to a completed shell may be just four to five weeks. Tiltup can progress while other elements are being fabricated, for example roof steel.
Safe and simple construction process: Much of the work is on the ground; there is no vertical formwork, no scaffolding and, since the floor slab is poured first, tilt-up workers have a safer working surface. This also means that good quality, well-compacted concrete is readily attained.
Low maintenance, durable buildings: Tilt-up offers reliable durability, as attested by buildings dating back to the 1940s.
Maintenance costs are reduced because the wider panels minimise the number of joints and sealants.