Expert Day "Sustainability in Construction"
On 25th January 2021, an expert day on the topic of "Sustainability in Construction" was digitally organised on the initiative of Saint-Gobain and RWTH Innovation GmbH. In total, more than 90 interested specialists and managers from the concern learned about the latest findings of resource-saving measures developed or propagated at RWTH Aachen University in the course of 5 presentations. Our chief engineer Alexander Feil spoke at the event on the topic of "Secondary construction raw materials - new challenges in processing technology".
In his remarks, he pointed out that the high quality of the produced recycled products is determined not only by the quality of the input material, but above all by the technical depth of the recycling measures. Sorting stages are often dispensed with for cost reasons. Correspondingly, low-threshold processed recycling materials can only be used in the simplest applications (e.g. as base layers in road construction) due to limited qualities. Higher qualities can be achieved by separating the foreign materials that usually occur in deconstruction measures, e.g. wood, plastics, asphalt and gypsum. As a supplement to classifying stages, sensor-based sorting can be used to achieve an additional improvement in quality. When designing the process, however, it must be taken into account that for good sorting performance, it is essential to provide preconditioning besides screen classification; this relates above all to the manipulation of the material flow in such a way that both sensory individual particle detection and individual particle separation can be maintained. A prerequisite for this is the separation of the material flow with additional distance between the particles prior to detection process. Results from an EU research project showed that foreign materials such as gypsum can be reliably discharged at throughputs of up to 10 t/h with a yield of up to 85 %.
However, the main obstacles to the use of sensor technology in the field of secondary construction materials are the high mass flows required and the generally low market value of the products produced. While these challenges make it unlikely that this technology can be used economically in Germany at present, there are already the first construction material processing plants abroad that are working successfully with sensor technology. Nevertheless, in view of the expected shortage of high-quality gravel and sand or solid rock deposits, it is to be expected that there will be a growing market for high-quality secondary construction raw materials in the future. In the course of the politically desired recycling, the use of sensor technology could make it possible to recycle at least a portion of the approximately 1 billion tonnes of construction waste produced annually throughout the EU.