Open-access paper on Re:Crete in 'Structures' journal
© 2022 EPFL
Our open-access paper on "Re:Crete – Reuse of concrete blocks from cast-in-place building to arch footbridge" is now published in Structures, the research journal by the Institution of Structural Engineers (Elsevier). Authored by J. Devènes, J. Brütting, C. Küpfer, M. Bastien Masse, and C. Fivet from the Structural Xploration Lab, the peer-reviewed paper presents the entire design and construction process of the footbridge. It concludes with a comparative life-cycle assessment of the footbridge and four alternatives: reused concrete outperforms recycled concrete and recycled steel; and is almost as 'green' as timber!
DOI to publisher: 10.1016/j.istruc.2022.07.012
Link to infoscience: https://infoscience.epfl.ch/record/295996
About 9% of anthropogenic greenhouse gas emissions worldwide are due to the production of cement, key constituent of concrete. Concrete also contributes to a large share of demolition waste, usually coming from building structures that are discarded because of functional obsolescence rather than of technical deficiency. Current practice for treating end-of-life concrete is to landfill it or crush it into aggregates used in new concrete mixes. Instead, a little-explored strategy consists in extending the service life of concrete elements by reusing them in new constructions. Following this paradigm, this paper presents a proof-of-concept prototype that reuses blocks cut out of obsolete cast-in-place concrete walls for a new structural application: a 10 m-long post-tensioned segmented arch footbridge. The paper details the design, material sourcing, and construction processes while highlighting the unusual features of the approach. The structural behavior is verified with a finite element analysis model and validated by load testing. A comparative life cycle assessment shows that the arch construction presents a significantly lower global warming potential then recycled concrete (−71%) or steel (−74%) alternatives and is very competitive to a timber one (+9%). In conclusion, the project proves the feasibility of a new circular economy application for the construction industry, in which new and reliable concrete structures are built with little to no cement inputs.