Demountable building
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Demountable construction is a construction technique that is intended to enable energy and resource-saving recycling of building materials in the construction of traffic routes , construction site (s) and in wood and concrete construction . The aim is the recultivation of habitats and the reclamation of building land . The prerequisite is a waiver of floor sealing .
Use in transport
Roads can temporarily be made of easily removable, compacted gravel , gravel or sand pavements; they are often an emergency lane at road sags , in the event of water pipe bursts or ( natural disasters ) on or near the traffic route . A temporary emergency track can also be used on railways in the event of rail accidents or broken trains .
Energy balance when demolishing concrete structures
If a building or other concrete structure has become superfluous, whether it is out of date or no longer meets new usage requirements, it is usually demolished . The demolition material is disposed of in a landfill or, in a more favorable case, recycled . Demolition and recycling require a lot of energy: demolition devours approx. 275 mega joules per ton, and breaking concrete approx. 85 MJ / t. For a structure with 1000 m³ of concrete that is 2.5 × 275 = 690 gigajoules for demolition and 2.5 × 85 = 212 GJ for crushing. If the recyclate is used as aggregate in new concrete, cement is used that was burned with high energy input, which produced a lot of CO 2 . Today's firing technology requires an average of 3500 kJ for 1 kg of clinker , and around 600 kg of CO 2 are produced per t of cement. Assuming a cement content of 300 kg / m³ of concrete, the energy expenditure is 300 × 3500 = 1.05 GJ for one cubic meter of new concrete and 180 kg of CO 2 are produced . There is also about 8 MJ / m³ for mixing the concrete.
The environmental impacts mentioned - energy consumption and CO 2 emissions - can be avoided if a structure is designed to be demountable. Dismantling requires less energy than demolition, and if it were still possible to reuse components as a whole, a lot would be done for the environment.
Advantages of demountable construction
But there are also other reasons for demountable construction: Demographic developments are changing the composition of a society. What is needed in residential buildings today will no longer suffice tomorrow. The need for housing per person is increasing, but more smaller apartments are needed as households become smaller. So it would be desirable either to change buildings during the usage phase or to dismantle them after usage and reassemble them in a different layout. That this is possible has already been demonstrated on high-rise buildings in Holland and in East Germany.
Not only apartments require occasional adjustments, office buildings do too. A building in Vienna was designed to be dismantled according to plan, dismantled after some time, transported approx. 20 km and reassembled at another location.
The demographic change in urban districts means that z. B. Schools are no longer needed when the children are absent. This was the reason in Holland to design demountable concrete structures. The buildings are so flexible that they can be used for school, office, college or hospital. A catalog of five types is published by the Dutch Ministry of Construction. A new system was presented in 2005, which consists of TT slabs made of reinforced concrete and columns and beams made of steel-concrete composite elements. Because of the relatively heavy design, the system is particularly suitable for office and industrial buildings. All connections are screw connections. A removable car park system is also on the market.
A demountable and remountable system from Germany consists of prefabricated double shell elements that are used as external walls and insulated with expanded glass . The inner walls are filled with gravel as a heat storage mass. During dismantling, all materials are sorted according to type and reprocessed.
The idea of demountable buildings has existed for more than 30 years, but has never been realized on a large scale. The only country where you can find it regularly is the Netherlands. In the bridge construction, temporary bridges were occasionally designed and implemented that could be dismantled. Tower constructions made of wood and steel, in particular transmission towers and overhead line masts, were dismantled if necessary and rebuilt elsewhere - sometimes in the immediate vicinity of the old location.
See also
literature
- ^ Lünser, H. Life cycle assessments in bridge construction. Birkhäuser, Basel 1999
- ↑ Weil, M., Jeske, U., Schebek, L. Use of natural and recycled aggregates in concrete production. BR building material recycling and landfill technology 19 (2003), No. 1, pp. 30–41.
- ^ Association of German Cement Works. Activity report 2005–2007, pp. 24 and 49
- ↑ Köhne, JH Demonteren en opnieuw begin in Middelburg, Cement 38 (1986), No. 8, pp. 40-45
- ↑ Hasslinger, W. demountable and re-erectable precast reinforced concrete building. In Reinhardt, HW, Bouvy, JJ (Eds.) Demounable concrete structures. Delft University Press, 1985, pp. 37-49
- ^ Ministerie van Volkshuisvesting, Ruimtelijke Ordening en Milieubeheer. Demountable building systems in concrete. The Hague 1996
- ↑ Herwijnen, F. van, The development of a demountable and adaptable construction system. Concrete + Precast Yearbook 2004, pp. 186–194.
- ↑ a b Forster, J. temporary to permanent. Buildings that can be remounted from concrete double wall panels. Opus C, 1st 2005