Potential for use of activated clays in concrete in Sweden – Roadmap

The Swedish construction industry is generating a save and affordable built environment for transport, work and living but it is faced with a huge challenge: drastic reduction of greenhouse gases and an increase of circularity in their production cycles. One material, which has inherently embodied CO2, is limestone, which is needed for the production of Portland cement, the essential ingredient in concrete. The CO2 emission during cement production can be drastically compensated by so called supplementary cementitious materials (SCM), which replace cement components causing CO2 emissions. SCM can be used by incorporating them into Portland cement or can be used directly by mixing into concrete. However, traditionally used SCM such as ground granulated blast furnace slag or fly ash are only available in limited amounts in Sweden, not matching the domestic cement production. An alternative to those more traditional SCM is activated or calcined clay, which reacts similar to blast furnace slag or fly ash. Calcined clay is created from natural clays by heating up to 700 ° - 800 °C, where it become very reactive. In this roadmap the state-of-the-art about activated clays is shown from a Swedish perspective. It also shows challenges and needs that have been formulated for a future implementation of activated clays as a component of low carbon concrete