Robert J. Flatt is Professor for Physical Chemistry of Building Materials at ETH Zürich since 2010. Before that he was Principal Scientist at Sika Technology AG for 8.5 years and postdoctoral researcher at the Princeton University for 2.5 years. He owns a master in Chemical Engineering and a PhD from EPFL (Switzerland). His main research topic is the working mechanisms of chemical admixtures, which can be considered as the “spices” of concrete. Hi interests lay in the molecular design of such admixtures to achieve targeted improvements of macroscopic properties, in particular for reducing the environmental footprint of concrete. This work naturally feeds into research on digital fabrication with concrete, which is developed within the Swiss National Competence Centre on Digital Fabrication in Architecture. Another topic of interest is the preservation of stone in built cultural heritage. Recently, Robert co-edited the book “Science and Technology of Concrete Admixtures” with Prof. Pierre-Claude Aïticn. He has also received several awards including the RILEM Medal as well as the Ross Coffin Purdy and the Stephen Brunauer awards from the American Ceramic Society.
Chemical Admixtures: Basic Principles and Blended Cements
This presentation will begin by reviewing basic principles about the working mechanism and mutual interactions between chemical admixtures. It will then examine how such principles may be applied to blended cements, discussing implications on dispersion efficiency and flow retention in particular. Further to this, we will examine interactions between superplasticizers and accelerators as these are increasingly seen as a solution for cements with particularly low the clinker content. Another important issue for such cements concerns particle packing limitations. To this end recent results highlighting rheological behaviour at high volume fractions will be highlighted, providing a link to rheological questions covered in another keynote lecture.