Ecological concrete

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As Ökobetone be concretes referred to, which are composed in such a way that the resulting from the production of the starting materials and the production of concrete environmental pollution is minimized. As a rule, the mix compositions of these concretes differ from the normative specifications for concrete composition (e.g. in EN 206 / DIN 1045-2). Therefore, in these cases, approval from the state building authority or general building inspectorate approval is required on a case-by-case basis . Such approval already exists for interior components ( precast concrete elements ) of exposure class XC1.

Importance of eco-concrete

The enormous importance of concrete construction in the realization of the national and international goals for climate protection is illustrated by the fact that the production of the concrete raw material cement is associated with carbon dioxide emissions of around five percent of global emissions.

A significant improvement in the ecological balance of concrete is possible by reducing the proportion of Portland cement clinker. The desired requirements for the fresh and hardened concrete properties, such as flowability, workability, early and final strength and durability, must be ensured.

Overall, the cement-reduced ecological concretes have a global warming potential of approx. 30% to 70% less than the conventionally used concretes.

Manufacture and properties

composition

By reducing the water content, switching to a high-performance superplasticizer and a significant increase in the content of environmentally friendly reactive and inert fines, such as. B. blast furnace slag, fly ash and powdered limestone, a significant reduction in the proportion of Portland cement clinker can be achieved while maintaining the desired properties. These substances can either be contained directly in the cement or added separately as a concrete additive during concrete production . The principle presented usually results in a clinker reduction of approx. 30%.

Special properties

In the production of eco-concretes, research has primarily tried to produce an ecologically better concrete with the same compressive strength. However, the reduction in the proportion of cement changes other properties. For example, tests show that some eco-concretes are attacked much more quickly and more severely by the frost-thaw cycle, which limits their use for exterior components. In contrast, creep and shrinkage are significantly reduced with certain compositions.

literature

  • U. Nolting, M. Haist: Sustainable Concrete - Material, Construction and Use: 9th Symposium Building Materials and Building Preservation Karlsruhe Institute of Technology . Ed .: HS Müller, M. Kromer. KIT Scientific Publishing, 2012, ISBN 978-3-86644-820-9 , pp. 45 ff . ( limited preview in Google Book search).

Individual evidence

  1. ↑ US Geological Survey (Ed.): Mineral Commodity Summaries 2011 . Virginia, USA 2011, ISBN 978-3-8322-7297-5 .
  2. ↑ a b T. Proske, S. Hainer, M. Jakob, H. Garrecht, C.-A. Graubner: Reinforced concrete components made from climate- and resource-saving ecological concrete - technical innovation for the realization of sustainable concrete structures . In: Concrete and reinforced concrete construction 107, booklet 6 . Ernst & Sohn, June 2012, ISSN  0005-9900 .
  3. ↑ T. Proske, S. Hainer, M. Rezvani, C.-A. Graubner: Eco-Friendly Concretes with Reduced Water and Cement Contents - Mix Design Principles and Laboratory Tests . In: Cement and Concrete Research . No. 51 , September 2013.
  4. ↑ a b U. Nolting, M. Haist: Sustainable Concrete - Material, Construction and Use: 9th Symposium Building Materials and Building Preservation Karlsruhe Institute of Technology . Ed .: HS Müller, M. Kromer. KIT Scientific Publishing, 2012, ISBN 978-3-86644-820-9 , pp. 45 ff .