Reusing concrete in circular construction can now extend a building element’s lifespan by 50 to 100 years, thanks to a new assessment framework developed by researchers at KTH Royal Institute of Technology in Sweden and Tampere University in Finland.
Reusing concrete in circular construction has long made sense on paper. Concrete is the most widely used building material in the world, and its production accounts for roughly 8-9% of global carbon dioxide (CO2) emissions, about the same share as the entire aviation industry. The problem has been knowing whether used concrete is actually safe to reuse. Existing rules were written for new concrete, not for elements that have already spent decades in service, and that gap has kept reusing concrete in circular construction from becoming a mainstream practice.
A study published in January in the journal Materials and Structures directly tackles this. Researchers developed a performance-based probabilistic framework, a prediction system grounded in real-world measurements rather than generic rules. It calculates how much useful life a concrete element has left and what conditions will affect that life going forward.
The framework centers on carbonation, which happens when CO2 from the air reacts with concrete over time, slowly reducing its internal alkalinity, which is the chemical state that protects the embedded steel reinforcing bars (rebar) from corrosion. Once carbonation reaches the rebar and moisture is present, rust forms, expands, and cracks the structure.
Previous methods treated the moment carbonation reached the rebar as the end of usable life. This research models both phases: initiation, when carbonation advances toward the rebar, and propagation, the period between when corrosion starts and when it causes structural damage. Including propagation can add five to eight years or more of usable life, making reusing concrete in circular construction far more viable than older models suggested.
The researchers ran thousands of computer simulations using Monte Carlo analysis, a technique that tests a problem across many possible combinations of variables to map the range of likely outcomes. The simulations drew on data from two real precast concrete buildings in Sweden and Finland, both of which had been dismantled.
Precast concrete refers to structural elements cast in a factory and assembled on site, including hollow-core floor slabs, beams, columns, walls, and stairs. These are the primary candidates for reuse because they can be carefully removed and transported without being destroyed.
The study also examined how storage between deconstruction and reuse affects the condition of concrete. Moving an element from a dry indoor setting to a humid outdoor one accelerates carbonation, and the framework accounts for it.
One of the most practical findings involves surface treatments. Applying water-repellent coatings, such as silicone-based treatments, can cut corrosion rates by up to 70%. Targeted intervention, not wholesale replacement, can extend structural life by decades and confirms that reusing concrete in circular construction does not require perfect elements, just informed ones.
The ReCreate project, which contributed data to this research, ran a live demonstration at a 2022 expo in Helsingborg, Sweden. Researchers built a pavilion from salvaged precast elements taken from a demolished building on the same site. The pavilion consisted of 99% recycled material, and researchers calculated that reusing concrete in circular construction at that scale produced a carbon footprint 96% lower than using newly produced concrete.
Both lead authors serve on the Swedish Standards Institute committee developing national standards for the reuse of precast concrete products. Standards give builders, engineers, and project owners a shared language and a legal basis for decisions. Without them, reusing concrete in circular construction remains a niche choice. With them, it can become a default option.
The framework also challenges a widely used European standard, EN 16757, which rates carbonation aggressively enough that most precast elements would appear unfit for reuse. When real measurements from the ReCreate project replaced EN 16757’s conservative estimates, all elements assessed had sufficient remaining life. Being overly conservative wastes usable material. Being accurate preserves it.
The researchers also found that CO2 absorbed by concrete through natural carbonation over its full lifecycle accounts for less than 6% of the emissions produced during original manufacture. That means the climate benefits of reusing concrete vastly outweigh any other factor. Researchers are also finding ways to improve the material before it enters service, with studies showing that used coffee grounds can strengthen concrete while diverting organic waste from landfills.
The EU generates an estimated 450 to 500 million tons of construction and demolition waste each year, of which roughly a third is concrete. Reusing concrete in circular construction, guided by reliable science, enables far more to be made from what has already been made. The path toward lower-carbon construction does not always require new technology. Sometimes it requires looking carefully at what is already there.
