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Introduction
Site-cast precast concrete construction is generically known as `tilt-up'. This is a prefabrication system, using simple forming and reinforcing materials; casting, using ready-mixed concrete; and erection or 'tilting', using mobile cranes, of large structural or cladding concrete wall or frame units. These form partial or complete structures.
Tilt-up originated in the USA around 1900, and expanded during the 1950s because of the increased availability of ready-mixed concrete and mobile cranes. The technique spread to other countries as a fast, competitive and flexible construction system. However, it was first used in the UK and Eire around 20 years ago. Although more than 20 tilt-up projects have been undertaken, to date it has not been more widely adopted by the UK construction industry.
Why not?
Across the world, tilt-up has been used for many types of structure, including offices, warehouses, cinemas, religious buildings, schools, hotels, housing, cold-stores, food processing, agricultural buildings and electrical stations. In the UK, tilt-up has been predominantly restricted to plant rooms, agricultural grain-stores, smaller isolated structures, fire compartment walls and retaining walls for the recycling industry.
Since becoming involved with tiltup construction in 1989, I have found resistance at all levels within the construction industry, partially in relation to the tilt-up system, still regarded as a 'new' system by many UK contractors. However, this also extends to the use of concrete for above-ground structures.
The justification for these preconceptions are the:
legacy of concrete from the 1960s as a grey, purely utilitarian material misconceptions about the effects of weather on construction.
perceived higher costs associated with precast concrete techniques.
Solutions
Weather has little effect. Tilt-up has been undertaken in virtually all environmental conditions, ranging from the sub-arctic to desert. In all cases, localised adaptation of simple, costeffective procedures, such as heated tents, or working practices, such as concreting at night, allow tilt-up techniques to be applied. Other, more readily accepted methods, may be affected considerably by climatic conditions.
During the past two years, the UK has experienced mild winters combined with torrential rain. However, the system can be used regardless: during the very...