Sika is dedicated to advancing low-carbon materials in the concrete industry. As part of the federally funded "URBAN" initiative, supported by the German Federal Ministry for Economic Affairs and Climate Action (BMWK), Sika is actively engaged in research and development focused on upcycling concrete through a partnership between industry and academia.
Sika supports “URBAN” project: Upcycling of residual materials from concrete processing
The German-funded “URBAN” project (2022-2025) aims to conduct an industrial feasibility study on concrete recycling. Together with partners such as EHL, Kruft/Germany, Leibniz University Hannover, KIT, Karlsruhe, and Holcim Germany, Sika in Leimen is developing innovative processes for recycling used concrete. Although used concrete is mostly used today as bulk material or simple recycled aggregate, it is often downcycled.
URBAN aims to transform old concrete into new cement and high-quality aggregate. The process includes the crushing of old concrete, the separation of building materials and the reprocessing of the old concrete powder. The result is Belitzement, which offers similarly high final strengths to Portland cement, but with lower CO2 emissions, as calcium is extracted from waste concrete instead of limestone. An innovative step is the carbonation of the aggregate. By supplying CO2 in an autoclave, a gas-tight sealable pressure vessel used for the thermal treatment of materials in the overpressure range, a high-quality, carbonated aggregate is produced.
The result is CO2-neutral building materials of almost standard market quality. Sika develops specific additives such as superplasticizers (Sika ViscoCrete®), accelerators (SikaRapid®) and compaction aids (SikaPaver®). Thanks to the use of recycled materials and the saving of CO2 certificates, the recycled concretes could not only be offered in a more sustainble way, but also at a lower cost.
With the quantities of used concrete available in Germany each year, a significant proportion of the cement requirement could be covered. The project is complemented by Sika's reCO2ver process, which recovers natural aggregate in its original quality and absorbs more CO2 than it releases. The combination of both processes makes it possible to meet the highest requirements for concrete components.
