Recycling Potential of Cellular Lightweight Concrete Insulation as Supplementary Cementitious Material

Buildings are responsible for 40% of the total energy consumption annually in Europe, along with the respective greenhouse gas emissions. To mitigate these impacts, intensive research is ongoing in the sector of Nearly Zero-Energy Buildings (NZEBs). Within EU-funded project iClimaBuilt, RISE is developing and improving the formulation of cellular lightweight concrete insulation (CLC) as a sustainable and recyclable alternative for organic insulation materials (ex. Expanded polystyrene (EPS)). Compared to EPS, this material is non-combustible and achieves similar performance as existing insulation materials (thermal conductivity of 40 mW/(mK)) while economically more attractive (EPS 60 EUR/m3, CLC 50 EUR/m3). In addition, the material is easily recyclable since it is 100% mineral based. It is also similar or lighter in weight than traditional EPS (around 80 kg/m3). At these ultra-low densities as for concrete, the material integrity was ensured by adding polypropylene micro-fibres. To further improve the thermal conductivity of CLC, granulated silica aerogels were implemented in the mix. The CLC was implemented in a lightweight sandwich-panel in form of a prefabricated block similar to currently used EPS-sheets. The recyclability of the material as an SCM for new cement production is being evaluated by a reactivity study of grinded and reheated (recalcined) material. The panel prototypes will be tested in a laboratory and validated in the living labs – real-life test and experimentation buildings in different climate zones in Europe.