C3-V1.5: demolition, dismantling and recycling of C³ structures
Table of contents
Project data
| Titel | Title TP C3-V1.5-I-d: Konzeption Großbauteile und Lastenheft „Herstellung“ im Verbundvorhaben C3-V1.5: Abbruch, Rückbau und Recycling von C³-Bauteilen | TP C3-V1.5-I-d: Conception large scale structures and specification „production“ as a part of the joint research project C3-V1.5: demolition, dismantling and recycling of C³ structures Förderer | Funding Bundesministerium für Bildung und Forschung (BMBF); Projektträger: PT Jülich / C3 – Carbon Concrete Composite Zeitraum | Period 01.03.2016 – 30.06.2018 Leiter Teilvorhaben | Subproject manager Prof. Dr.-Ing. Dr.-Ing. E.h. Manfred Curbach Bearbeiter | Contributor Dipl.-Ing. Sebastian May Projektpartner | Project partners Institut für Baubetriebswesen, TU Dresden (Verbundkoordinator) | Institut für Baustoffe, TU Dresden | Lehrstuhl für Betriebliche Umweltökonomie, TU Dresden | AIB GmbH, Bautzen | CARUSO Umweltservice GmbH, Großpösna | MÜLLER-BBM GmbH, Dresden | steinbeisser GmbH, Landsberg | KLEBL GmbH, Gröbzig |
Report in the annual report 2018
WHAT TO DO WITH THE WASTE?
Uncovering textiles by hand
A sustainable and resource-efficient material chain must be reasonable also beyond the component life cycle. The research project
C3-V1.5 deals with exactly this challenge. A so-called downcycling of the primary carbon and concrete components needs to be prevented, otherwise the building material loses its initial quality and superior properties. Reuse or efficient material utilisation of the primary material components equates a resource-conserving recycling and a sustainable use of materials.
Zug- und Querkraftüberprüfung von zwei gestoßen Carbonbetonplatten
In addition to the conceptual design and production of slender, material efficient new components, the reuse and recycling of the building material carbon reinforced concrete has been studied for the last 3 years. Furthermore, approaches for a joining technology were onsidered theoretically and then tested under laboratory conditions. The idea behind this is to separate durable carbon reinforced concrete components after primary use and to reassemble them for a second use. For this purpose, thin plates were concreted in the laboratory with a carbon textile and a connecting element, clamped force-fit and then tested for maximum load capacity in the longitudinal and transverse direction to the coupling point. An early failure could not be detected. Therefore, nothing stands in the way of using it practically.
The large discontinued components from the annual report 2017 were separated into their individual components carbon reinforcement and concrete and then used in small-sized tests by partners. The recycled textiles and the shredded textile threads were re-concreted and tested in standard tests. The test results and findings were partly promising and indicate further research potential. On this base there will be more producing and testing of recycled carbon textiles in the C3-V-I.13 project.
Report in the annual report 2017
DEMOLITION FIRST, BUILDING SECOND
4-point bending test of a ripped slab made of carbon concrete
In this project, we are dealing with the total material chain life cycle of components made of carbon concrete. Both materials, carbon, and concrete, as well as the resulting composite – carbon reinforced concrete – are considered. Furthermore, the production, use, conversion, and modernization, as well as the demolition and reuse of large components are examined. Individual small-scale tests were successfully carried out in 2016. In 2017, the goal was to verify the results of prior research on large-scale specimens. So, two space-enclosing buildings made of carbon concrete were prefabricated and built. The precast components used for bearing and non-bearing walls were just 8 cm thick. The slab thickness of the 2 double tee beams was just 6 cm. These ‘small‘ carbon concrete cabins had a footprint of 5.0 m × 2.5 m and a height of 2.7 m. 2D textiles and rods made of carbon fibres served as reinforcement. Both reinforcement manufacturers are important partners in the entire C3 project. To demolish both cabins, concrete drilling, separation techniques and dismantling work were carried out, all of which may be required while renovating the buildings or at the end of their service life. But such type of activities may be required during production, as well as during construction as well, e.g., in the case changes are requested by the planner or the user. In the demolition tests, we could determine that the material carbon concrete – despite its excellent compound properties – could be very well separated into the two raw materials: reinforcement and concrete. Further tests for characterization and reuse of the recovered carbon fibres are being carried out.
The design methodology proposed for large components made of carbon concrete was corroborated by testing a ceiling element in the Otto Mohr Laboratory. As a result, the elements’ load bearing capacity was determined, as such results are important for other C3 projects. The calculated failure load differed by just 3% from the experimentally determined ultimate load. Currently, a modular ceiling component made of carbon concrete is being planned and its load bearing capacity is calculated. The design assumes that the element may be strengthened in the future, using an external post-tensioned carbon reinforcement, as it may be required if the applied external load were going to increase. The prestressing technique for carbon rods developed within the C3 project V4.2 was used.
Report in the annual report 2016
Sustainability of carbon reinforced concrete
Carbon reinforced demolition material
In September of 2015, the international community agreed on the ‘2030 Agenda’ at the UN Summit on Sustainable Development. The agenda’s intentions include, among other things, a sustainable use of resources, as well as a reduction in energy requirements and greenhouse gases in the coming years. The C3 project is committed to such objectives, and it has implemented them successfully in the project C3-B2, developing sustainable concepts for binders and concrete in the future.
Within the project C3-V1.5, we are creating a sustainable approach to the complete life cycle of a building or a component made of the innovative material carbon reinforced concrete (in short: carbon concrete or C3). In the project, the production stage, use, renovation and modernization, as well as the demolition and recycling of carbon concrete components were taken into consideration. Such a dismantling work involves not only the removal of components either during the rehabilitation of a structure, or at the end of its service life, but also during the construction phase.
The goal is to ensure that all materials used in the life cycle remain in the economic cycle. A so-called ‘down cycling’ of the primary carbon and concrete components needs to be prevented, otherwise the building material’s initial quality and superior properties will be lost during the material recycling. Reuse or efficient material utilization of the primary material components can be equated with resource-conserving recycling, and also with a sustainable use of materials. At the project’s end, specifications for the construction of buildings and structural elements made of carbon reinforced concrete as well as a specification including the remaining materials during demolition and recycling will be developed.
In the first months of the project, samples were produced. With these, tentative tests were carried out with different processing methods – drilling, lifting, sawing – and corresponding emissions were measured. The carbon concrete slabs could be recycled with less effort: it was easier to separate carbon reinforcement than steel bars from the concrete. Significant results of the emission measurements have already been obtained from the on-going test program. Currently, large components are scheduled to be tested in 2017, for which demolition and recycling processes are be verified under realistic conditions.