A favorable carbon footprint for the construction industry

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A Swiss startup is turning concrete rubble into high-quality limestone that also stores carbon dioxide

Concrete largely consists of cement, whose production accounts for around seven percent of global greenhouse gas emissions. The Swiss startup Neustark has now greatly improved the poor CO₂ balance of this ubiquitous construction material. The team headed by Johannes Tiefenthaler and Valentin Gutknecht has developed a technology that extracts carbon dioxide from the atmosphere and locks it up in concrete rubble, which is primarily created by the demolition of buildings. When CO₂ reacts with the calcium hydroxide in concrete, it results in new high-quality limestone that can replace newly produced cement in the production of fresh concrete. This technique enabled the company, which was outsourced from the Swiss Federal Institute of Technology (ETH) in Zürich three years ago, to improve the climate performance of fresh concrete by 10 percent. Neustark’s next plan is to make climate-neutral concrete a reality by 2025.