Reuse of hollow core slabs - From idea to action

Katja Udbye Christensen

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Reuse of hollow core slabs - From idea to action

Project start May 2022. Expected completion October 2023


Precast concrete elements are the most difficult type of construction material to reuse directly and one of the biggest barriers is the lack of legislation in the construction field. This means that the building owner must apply for a dispensation from the Danish legislation if reused precast concrete elements are to be used in a new building. Thus taking on an increased responsibility of the security and safety of the building.

In Denmark, there are currently no requirements or norms on how reused precast concrete elements must be removed from existing buildings or how the properties must be documented and declared. The properties of new precast concrete elements are mainly documented through the production process and therefor the procedure for documentation cannot be directly transfered.

Based on a building project in Norway, where hollow core slabs from one building was reused in a new one, a Norwegian standard on removal and documentation of recycled hollow core slabs was published. Even though a large part of our legislation today is based on EU-legislations, we still have many national requirements to construction and construction materials which might hinder an direct implementation of the standard in Denmark.


The aim of the project is to come up with specific suggestions for Danish requirements on testing and documentation of recycled hollow core slabs. This is achieved through a number of sub-goals, including:

  • Examination of the Norwegian standard in relation to its suitability in Denmark including evaluation of the suggested plans for testing.
  • Mapping of specific methods for documenting concrete strength and reinforcement properties.
  • Carrying out tests on reused and new hollow core slabs.
  • Assessment on the significance of the stated requirements through analyzes of several cases.


  • Danish Technological Institute (project manager)
  • University of Southern Denmark (SDU)
  • COWI
  • ETA-Danmark
  • Tscherning
  • Søndergaard
  • Enemærke & Petersen
  • Boligbeton

The projected is partially financed by We Build Denmark.