Concrete slabs, beams, columns and other elements from dismantled buildings can be safely reused in new construction, according to a new study. The analysis could facilitate incorporating concrete—currently responsible for as much as 9% of global greenhouse gas emissions—into the circular construction industry and make the building sector as a whole more sustainable.
“Due to its durability, concrete can have a long life, and if we reuse it, we maximize its longevity, and avoid the carbon-intensive process of producing new cement and the energy-heavy machinery required for crushing and recycling waste,” says study team member Arlind Dervishaj, an architect and graduate student at the Royal Institute of Technology in Stockholm, Sweden.
Building codes generally require concrete to be sound for at least 50 years. When buildings are torn down (even before the 50-year mark, as is increasingly the case) it’s usually assumed that concrete’s useful life is over. Old concrete either gets landfilled or downcycled into rubble for road construction or aggregate for new concrete production.
That’s a major missed opportunity, the new study suggests.
But until now, there has been no organized method to evaluate the potential of reusing salvaged concrete. The researchers ran thousands of computer simulations to predict the future lifespan of reused concrete, based on measurements of the condition of existing buildings.
“Our study demonstrates that we can scientifically guarantee a ‘second life’ for these elements, shifting the perspective of old buildings from end-of-life waste to a valuable resource of durable components,” says Dervishaj.
The future lifespan of a given piece of concrete depends on its past use, storage history, climate conditions like humidity and atmospheric carbon dioxide concentration, and how it is deployed in its second life.
For example, a concrete slab that has been exposed to harsh elements for many decades may be best reused as an interior component. Repair and refurbishment techniques—such as waterproof coatings—can also extend the lifespan of concrete.
The researchers constructed a flowchart to help builders be confident that reused concrete components will be structurally sound for the anticipated lifetime of a new structure. “We can prove that much of this concrete is safe for another full service life,” says Dervishaj. “It’s a positive ‘re-discovery’ of a material we already have.”
To facilitate re-use, the history of concrete components will need to be tracked in an organized way. Ground-truthing of the researchers’ rubric is also necessary: “We now need to monitor real-world projects with reused concrete to see how it performs under changing exposures,” says Dervishaj.
“We are currently working on the first comprehensive standard for precast concrete reuse in Sweden—and arguably the first of its kind in Europe,” Dervishaj says. The researchers hope their approach will eventually lead to Europe-wide and perhaps even international standards for concrete reuse.
Source: Dervishaj A. et al. “From durability to circularity: ensuring service life and enabling reuse of concrete in circular construction.” Materials and Structures 2026.
Image: ©Anthropocene Magazine
