Ashes from waste incineration are mostly disposed on landfills. For these residues, which contain mineral and metallic smelting products, there is the potential of a waste volume reduction by recycling. In order to obtain suitable source material for recycling, toxic contents above statutory limits must be identified and separated. However, the residues also contain valuable and scarce heavy elements such as tin, molybdenum, tungsten, and cobalt; the recovery of which is likely to be economically viable. By recycling these secondary raw materials, they are not removed from the economy and favor a sustainable cycle of materials by reducing consumption of primary resources.

In the joint research project ASHCON, the use of residues from waste incineration as a substitute concrete aggregate is examined. For this purpose, the project partners study the secondary raw materials´ interactions with source materials in concrete production. The properties of the resulting fresh and hardened concrete are evaluated in order to prove suitability for recycling concrete. By fractionating residues into valuable, interfering, and toxic substances, and furthermore, characterizing input, intermediate and final products, the upcycling performance for the initial residual material is assessed. AiNT is involved in the research project ASHCON to test and optimize its own analysis technologies for the non-destructive characterization of ashes from waste incineration.

The advantages of prompt gamma neutron activation analysis pose an added value within the research project, since an integral element analysis of the input material as well as the intermediate and end products is conducted independently of sample properties. By this sensor technology, e.g. contaminants can be identified in real time and separated by downstream sorting processes.

In order to assess the residues´ influence on various properties of the recycled concrete, detailed investigations are carried out. Concepts for the production of substitute construction materials using the residues from waste incineration are developed in a practice-oriented manner. As part of ASHCON, AiNT is evaluating the performance of the prompt gamma neutron activation analysis for determining the levels of toxic and interfering elements in order to ensure that statutory limits are reliably met. In addition, system optimizations are developed to further improve sensitivity, reduce measurement time and accelerate the evaluation of the complex, high-energy gamma spectra. Based on experimental analyses and knowledge gained, a measuring system is designed for the specific application.

AiNT develops and tests measuring systems for element analysis based on prompt gamma neutron activation analysis (PGNAA). These measuring systems facilitate non-destructive element analysis for a wide variety of sample materials. PGNAA differentiates from existing methods by conducting analyses without sample preparation. During measurement, a gamma spectrum is obtained, and the elemental composition of the material is derived. One advantage is that, apart from crushing of large grains, no sample preparation is required, which allows short periods of time between sampling and analysis. Results are available to the project partners in a timely manner.

The following public institutions and private companies are involved in the joint research project ASHCON:

TH Köln – University of Applied Sciences
Fraunhofer Institute for Building Physics IBP
Münster University of Applied Sciences
RWTH Aachen University
Aachen Institute for Nuclear Training GmbH
Fertigbeton Rheinland GmbH & Co. KG
METTEN Stein+Design GmbH & Co. KG

The ASHCON project is funded by the Federal Ministry of Education and Research (BMBF) under the grant number 033R258B as part of "Resource-efficient circular economy - Building and mineral material cycles (ReMin)". ReMin is part of the “Research for Sustainable Development - FONA” framework.