Research Seminar - June 2021
Friday, June 11, 2021
Time: 1:00 pm
Presentation title: Reduction of CO2 emissions by means of calcined clays – a challenge for concrete technology?
Calcined clays offer the opportunity to fulfil environmental requirements, to counteract the shortage of resources and to provide the global market with high-performance binders, in synergy with other composite materials. Clays that are of future interest do hardly release carbon dioxide during their thermal activation (calcination) due to low carbonate content or calcination temperatures below decarbonation. Clay deposits are available worldwide in sufficient quantities. A suitable calcination process in technical facilities is urgently required for a pozzolanic contribution of the clays, especially of their phyllosilicates, in concrete. Their properties differ significantly from those of glassy materials and require a fundamental knowledge regarding workability and durability issues.
It is commonly known that the workability of fresh concrete is reduced with the addition of calcined clays due to their high specific surface area and an increased water demand. Heterogeneous or strongly negatively charged surfaces, as can be found in clays with complex compositions, face concrete technologists with a huge challenge when selecting appropriate superplasticizers. A further problem is rapid slump loss that has been observed for calcined clay blended cements with conventional superplasticizers. This lecture will provide possible approaches to face these problems in future.
Ricarda Sposito was doctoral candidate and research associate at the Institute for Construction Materials, University of the Bundeswehr in Munich, Germany. She received her B.Eng. in civil engineering from University of Applied Sciences Munich in 2013 and her M.Sc. in civil engineering from Technical University of Munich (TUM), Germany in 2015. Her research interests include concrete technology, especially the formation of the interfacial transition zone, as well as calcined clays as supplementary cementitious materials and their interaction with superplasticizers in cementitious systems.