Precast Concrete Cladding
Description
Precast concrete panels are precast reinforced concrete units available in a wide range of mixes, colours and finishes. Finishes can include acid-etched, smooth or coarse ground, grit or sand-blasted, rubbed or polished. Mixes designed to resemble natural stone can also be produced (see Reconstructed Stone Cladding). Highly articulated designs can be accommodated by the mouldable concrete mix.
Benefits
Precast concrete
- Enables faster programme times - not affected by weather or labour shortages.
- Improves buildability - early enclosure of dry envelope enables follow-on trades to start sooner.
- Produces a high standard of workmanship in factory conditions - reduces potential for accidents, addresses on-site skill shortage.
- Has a high quality finish that can be left exposed - concrete's thermal properties can be exploited in low-energy buildings.
Process
Precast concrete panels are cast face-downwards in purpose-built moulds, made of timber and lined with fibre glass. A steel reinforcement cage is placed in the mould prior to the concrete being poured. Timber moulds can be easily adjusted so that maximum use can be made of each basic mould, further contributing to cost efficiencies. By adapting the base of the mould different designs and effects can be created - from false joints to intricate leaf patterns, see C.C.A.N. case study. Increasingly, maximum use of off-site fabrication is being made by fixing other elements, from insulation to entire windows, during manufacture of precast panels (see Swindon Hospital). Once de-moulded, the exposed surface of the unit can be treated in a variety of ways - acid-etched, smooth or coarse ground, grit or sand-blasted, rubbed or polished.