Resource-efficient and safe concrete production -
key to comprehensive and sustainable recycling of mineral material streams
The production of building materials such as cement and concrete is a major contributor to the greenhouse gases emitted worldwide, especially of CO2. Further, in Germany alone, the construction industry is responsible for approx. 40 % of the national mineral resources consumption. At the same time, there is only very limited to no ‘real’ recycling in this sector. The current mode of operation so far is rather characterized by down-cycling than recycling: Currently, only 25 percent of the construction waste generated in Germany is recycled - despite scarce raw materials and a shortage of building materials.
This is where the joint research project "ReCyCONtrol" comes in, which is coordinated at the Leibniz University Hannover (LUH) and involves several partners from science and industry. The goal is to develop new methods based on the use of artificial intelligence (AI) and computer vision (CV) for a high-precision control of the concrete production process especially with regard to sustainable, resource efficient and climate friendly concretes. In this way, high-quality (re-)use of existing construction demolition material will be made possible. The German Federal Ministry of Education and Research (BMBF) is funding the project with approx. four million euros over the next three years.
Background
There are many reasons for the gap in the building materials cycle, but one main cause can be identified: The composition of the materials to be recycled, the so-called recyclates, is subject to large fluctuations. This has pronounced negative effect on the robustness and quality of the new concretes produced from these recyclates. It is possible to compensate for these fluctuations by significantly increasing the cement content (in some cases by up to 20 percent). However, this is neither economically nor ecologically justifiable. The use of recycled materials, which is desirable for environmental reasons, is thus in direct competition with the required reduction of greenhouse gas emissions in concrete production. Another approach to counteract these fluctuations is the separation of detrimental components by sieving. However, the quality of the separated residual materials is then usually too low to be used even for down-cycling and therefore, have to be deposed. As a consequence, this approach is also not expedient.
All of the above named disadvantages of existing techniques (which are basically used worldwide) are ruled out by the ReCyCONtrol-approach, brought forward by the consortium.
Goal of the project ReCyCONtrol
In order to be able to make greater use of concrete recyclates, the ReCyCONtrol research group develops technologies that make it possible to continuously record and control the influence of different compositions of these substances on the end product without negatively affecting the economic efficiency and environmental balance of the end product. The acronym "ReCyCONtrol" is derived from this objective and represents the central concepts: "REcycling", "CYbernetic", "CONcrete" and "conTROL". The developed techniques however certainly are applicable to all kinds of raw materials.
In order to raise concrete production to the Industry 4.0 standard, automated, self-learning process monitoring, control and regulation methods will be required in the future. To detect the fluctuating composition of the concrete raw materials, the project develops AI and CV based methods using contactless imaging sensors, a. o.. On this basis, to control the properties of the end product concrete, additives, that are specially developed for the purpose of this project, will be added during the mixing process. The companies involved in the project are MBCC Group - Master Builders Solutions Germany (formerly: BASF), HeidelbergCement Group, Pemat, Bikotronic and alcemy, as well as the Federal Waterways Engineering and Research Institute (BAW) and the Leibniz University Hannover (Institute of Photogrammetry and GeoInformation, Institute of Building Materials Science).
"The research topic is of great importance for industry, certifiers and planning bodies," explains Prof. Dr.-Ing. Michael Haist (Institute of Building Materials Science, Leibniz University), who developed the project together with Prof. Dr.-Ing. Christian Heipke (Institute of Photogrammetry and GeoInformation) and the industry partners. "It is a clear signal of the importance of the research project that we have been able to attract research partners from all the participating industrial sectors and, in addition, well-known supporters who are accompanying the project with their expertise," adds Professor Heipke. The supporting companies (Hochtief AG, Insensiv GmbH, Moß Abbruch-Erdbau-Recycling GmbH & Co. KG) highly welcome the research project and, as industry leaders in their respective fields, see a clear value of the planned research for future tasks in the construction industry.
