MIN-LOOP - Mineral foam made from recycled sand makes lightweight concrete ceilings more environmentally friendly

Resource-efficient circular economy - construction and mineral material cycles (ReMin)

Rigid polystyrene foams are often integrated into concrete components to make them lighter. However, these are difficult to recycle. The MIN-LOOP project aims to develop a mineral foam made from recycled sand to replace polystyrene and research its properties in the ceiling element.

The project is being funded as part of the "Resource-efficient circular economy - construction and mineral material cycles (ReMin)" funding measure. "ReMin" is part of the BMBF research concept "Resource-efficient circular economy" and is aimed at resource-efficient construction and the expanded use of mineral secondary raw materials from construction waste, slag, ash and mining residues.

Hybrid components - a challenge for recycling

Large-area polystyrene elements are integrated into ceiling elements as displacement bodies to reduce the inherent loads of the components. This meets the requirements for flexible use of space and resource-efficient use of materials with large spans. At the same time, technical components are increasingly being integrated, for example for heating in the ceiling cross-section, resulting in statically load-bearing and energetically functional hybrid elements.

These hybrid components, which are already very widespread today, pose a major challenge for subsequent recycling, as they can only be returned to a closed material cycle incompletely. In view of the expected increase in the number of hybrid components, it is considered imperative to replace rigid polystyrene foams as early as possible and to develop concepts for fully recyclable components. This also includes researching the material, load-bearing and deformation behavior. Almost complete mineral material cycles for hybrid ceiling elements, with the substitution of rigid polystyrene foam with mineral substitute building materials and the use of crushed sand, represent the central objective of the MIN-LOOP project.

New mineralized foam based on recycled sands

To this end, a mineralized foam based on recycled sands with a dry bulk density of around 500 kilograms per cubic metre is being developed under the leadership of TU Kaiserslautern. The development of reliable mix designs for the mineral foam and the material tests are being carried out at TU Darmstadt in collaboration with the company Wilhelm Röser Söhne GmbH & Co. The load-bearing behavior of hybrid ceilings with a mineral foam core is being investigated experimentally at the TU Kaiserslautern. Engineering models are derived from the results to describe the realistic load-bearing behavior.

Innogration GmbH develops process technologies to integrate media pipes, for example for heating and cooling, into the edge area of the mineral foam. This enables simplified recycling. In order to identify potentially negative influences on performance, numerical and experimental investigations are being carried out at the TU Kaiserslautern and recommendations for action are being derived. Betonwerk Büscher GmbH & Co KG is analyzing the recyclability of the mineral foam and the hybrid floor elements. The project is accompanied by a life cycle analysis at material, component and building level by the company ee concept gmbh.

New impetus along the entire value chain

The research project provides the entire value chain, consisting of building owners, planners, manufacturers and supervisory authorities, with new impetus for the creation of sustainable closed material cycles in the construction industry. By transferring the findings to concrete façades, synergy effects can be achieved and the field of application of the new technology can be expanded.

Funding measure
Resource-efficient circular economy - construction and mineral material cycles (ReMin)

Project title
MIN-LOOP - Substitution of polystyrene-based rigid foams with cement-bound mineral foam made from recycled crushed sand in sandwich hybrid ceilings for purely mineral material cycles in building construction


Funding reference

Funding volume of the consortium
1,129,039 euros

Prof. Dr.-Ing. Matthias Pahn
Technical University of Kaiserslautern | Department of Civil Engineering | Department of Solid Construction and Building Design, Working Group Building Design and Prefabricated Construction
Paul-Ehrlich-Straße 14 | 67663 Kaiserslautern
Phone: 0631 205-3083 | Email: matthias.pahn@bauing.uni-kl.de

Project participants
Darmstadt University of Technology, Institute for Materials in Civil Engineering; Innogration GmbH; Betonwerk Büscher GmbH & Co. KG; ee concept gmbh; Wilhelm Röser Söhne GmbH & Co. KG

Data sheet
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