(P)RECAST – Reuse of Precast Concrete Elements

Katja Udbye Christensen

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(P)RECAST – Reuse of Precast Concrete Elements

Project start in January 2022. Expected completed in June 2024.

Summary

The cement and concrete industry currently account for approximately 8% the of the global CO2 emissions; hence, there is a crucial need to reduce the overall CO2 emissions from cement and concrete in the construction sector. Also, challenges with scarcity of high-quality natural resources used for concrete production (especially in urban areas) emphasizes the importance of better resource utilization.

Denmark has a strong tradition in using precast concrete elements, and their substantial volume in the building stock represents a great potential to explore reuse opportunities. At present, in an end-of-life scenario, concrete structures are crushed after demolition and recycled either as aggregates for new concrete production or as subbase material under roads. Concrete has a long service life, especially when used indoors. When buildings with precast concrete elements are demolished, it is often due to culturally conditioned needs, e.g., urban development. Instead of crushing the precast concrete elements (thereby reducing their potential value as a structural element), they can be reused directly as in new buildings – yielding far greater environmental benefits when compared to recycled concrete aggregates.

However, the reuse of precast concrete elements is a new and a rather unexplored practice. Few projects have dealt with this due to the technical challenges that must be addressed. Thus, little innovation and novel techniques exist today. To overcome that, the (P)RECAST project brings a paradigm shift in the building sector with reuse of precast concrete elements as an alternative to concrete crushing and recycling, introducing a new circular value chain.

The project is partially funded by the Environmental Technology Development and Demonstration Program (MUDP) under the Danish Ministry of Environment.

Project objectives

The overall goal is to make reuse of entire precast concrete elements from existing buildings in new buildings possible, introducing new building components with low CO2 footprint and high resource utilization. The specific project objectives are to:

  • Develop a scheme ensuring production of reused precast concrete elements of the required quality through development of 1.1) new methods for careful dismantling and 1.2) new methodology to determine necessary properties and load bearing capacity.
  • Develop methods enabling reused precast concrete elements as structural elements including 2.1) development and documentation of new joints based on FEM-modelling and empirical research and 2.2) methods for incorporating the reused precast concrete elements in the structural design.
  • Develop new on-site construction methods for execution of structures based on reused precast concrete elements. 
  • Implement reuse of precast concrete elements through 4.1) creating reliable environmental data, 4.2) setting up a business case for each actor in the circular value chain accounting for the social, environmental, and financial value, and 4.3) carrying out demonstration projects proving that precast concrete element reuse is possible without compromising quality and safety.

Participants

  • Danish Technological Institute (Project leader)
  • Aarhus University
  • GXN Innovation/ 3XN
  • Aarsleff
  • Søndergaard
  • G. Tscherning
  • COWI
  • Peikko Danmark
  • Hi-Con
  • AP Ejendomme
  • Brabrand Boligforening
  • Dansk Standard
  • Dansk Beton

The picture at the top is from the dismantling of part of IKEA in Gentofte. IKEA A/S owns the right to the picture.