Concrete recycling
As a concrete recycling is re and re-use of concrete and its components, respectively.
Depending on the time of recycling , a distinction is made between fresh and hardened concrete recycling . Concrete residues are fed to fresh concrete recycling. B. incurred in the production of concrete and have not yet hardened. In hardened concrete recycling, on the other hand, hardened concrete is processed. B. is gained when demolishing buildings.
Fresh concrete recycling
In fresh concrete recycling, not yet hardened concrete residues are washed with water and the aggregate is separated from the cement paste . The aggregate can be returned to concrete production after subsequent sieving . The resulting residues in the washing of the concrete and also during washing of truck mixers resulting residual water containing cement particles and other fines and may in accordance with DIN EN 1008 of concrete production to the addition of water are added. This is known as residual water recycling . The permissible ratio of residual water to fresh water for a new mixture depends on the fine material content of the residual water and the required concrete quality. Concretes that are subject to particularly high requirements ( high-strength concrete , air-entrained concrete , ...) may generally only be mixed with fresh water.
Fresh concrete recycling is practically carried out by all German concrete manufacturers. With the process, almost all of the residual concrete that arises from the production can be returned to concrete production.
Hardened concrete recycling
The recycling of hardened concrete begins with the demolition of buildings through pre-sorting as pure as possible. Concrete waste is subsequently breaker for concrete gravel and crushed sand crushed. When demolishing reinforced concrete , the sorting out of reinforcing steel is also part of it. This steel scrap can be melted down to form new steel products.
Concrete chippings and crushed sand are available for various purposes. With klassiertem concrete chippings can recycled concrete are made. The requirements for this "recycled aggregate" are specified in the German standard DIN 4226-100. Since concrete chippings always consist of the natural aggregate that was used in the production and of adhering cement stone, in the production of recycled concrete u. a. a changed water demand can be taken into account.
Another large area of application for grit and sand from hardened concrete recycling is road and path construction. Concrete chippings can e.g. B. can be used for unbound base courses and replace grit from primary sources .
Crushing construction waste with a mobile crusher (blue)
Separation of the material according to grain size
Dust generation during sorting
Loading concrete chippings
See also
standardization
- German Institute for Standardization (Ed.): DIN 4226-100: 2002-02 - Aggregates for concrete and mortar - Part 100: Recycled aggregates .
- German Institute for Standardization (publisher): DIN EN 206-1: 2001-07 - Concrete - Part 1: Definition, properties, production and conformity .
- German Institute for Standardization (publisher): DIN EN 1008 - Additive water for concrete - Specification for sampling, testing and assessment of the suitability of water, including water that occurs during concrete production, as added water for concrete .
Individual evidence
- ↑ a b c Concrete recycling - recovery of existing substance. BetonMarketing Deutschland, accessed on December 24, 2013 .
- ↑ Residual water from reprocessing plants for concrete production. (No longer available online.) HeidelbergCement AG, archived from the original on October 30, 2012 ; Retrieved December 24, 2013 .
- ↑ What is RC concrete? ifeu Institute for Energy and Environmental Research Heidelberg GmbH, accessed on December 24, 2013 .