Sika announces funding award for new concrete-recycling technology that stores carbon

SPECIALTY  chemicals company, Sika, has announced that its reCO2ver technology is now receiving targeted support from Switzerland’s Climate Cent Foundation. The novel concrete-recycling process allows old concrete to be entirely reused while also locking in a significant amount of carbon dioxide. According to Sika, the climate protection programme is guaranteeing the purchase of CO2 certificates for an initial amount of CHF10m (US£11.2m). 

The construction and building sector is responsible for about 39% of global energy-related carbon emissions, 11% of which comes from materials and construction – in large part due to the vast amount of concrete produced each year. Currently about 30bn t/y is produced, but as the world’s population approaches 10bn, the global building stock is expected to double in size.  

The problem is further compounded, as the vast majority of the concrete demolition waste generated worldwide every year ends up in landfills. 

Finding ways to decarbonise the sector and reuse materials is, therefore, key to helping achieve climate targets. Sika’s reCO2ver technology claims to help solve both these problems.  

The technology has already been tested at a pilot plant facility in Switzerland. During its test phase, the plant processed up to 5 t/h of pre-crushed concrete demolition waste containing aggregates and cement stone. 

The system works by filling a hopper with demolition waste and then sending it to a rotating chamber where it comes into contact with CO2. The rotation separates the now carbonated cement stone from the aggregates, and additives are added to the mixture to clean the aggregates. Fine particles of the removed, carbonated cement stone are filtered out and collected, while the cleaned aggregates are separated into 0–4 mm, 4–8 mm, 8–16 mm, and 16–32 mm sizes in a sieving unit. 

Not only does the technology save on natural resources by completely recycling demolished concrete, but the process can also reduce water consumption by 40%, the firm said. 

Sika said that previously, attempts to recycle old concrete have led to rather low recycling rates, and only 30% of primary material can be substituted by these recycled materials in structural concrete. 

However, comparative testing of the Sika reCO2ver process has demonstrated that new concrete containing recycled content performs similarly to an all-new product. “Thanks to additionally developed chemical additives, other process optimisations can be achieved, such as the flexibility to tailor specific concrete functionalities,” the firm said. 

Sika added that by the end of 2030, the aim is to have stored approximately 17,000 t of CO2 in concrete demolition waste. And, in order to be able to document the climate-added-value benefits of the reCO2ver facilities on a standardised basis, it is working with climate consultancy firm South Pole on the development of a climate protection programme aligned with the requirements of the Swiss Federal Office for the Environment (FOEN).  

Philippe Jost, head of construction at Sika, said: “Thanks to our innovative strength and sustainable technologies, we enable our customers in the construction and automotive sectors to reduce their ecological footprint. This drives the transformation toward greater sustainability. We are delighted that the reCO2ver technology is being recognised through targeted support, and we are convinced that we are delivering significant added value to the construction industry, the environment, and future generations.”