Séminaire Navier : Roland Pellenq (CNRS-MIT-AMU)

New-electron conducting carbon-based cement electrodes

 

Abstract: Concrete is the most produced synthetic material on Earth and the second most consumed product after water. It consists in solid aggregates embedded in hydrated cement paste in which the cement plays the role of a glue, and provides a cheap and efficient way to build long-lasting solid structures. In that regard, cement has no equivalent to meet our societies’ needs for housing, shelter and infrastructure. Nevertheless, cement has a major ecological footprint that amounts to 5-10% of the worldwide CO2 emission, which needs to be significantly reduced or compensated by giving cement additional properties other than pure mechanical strength. A promising way to do so would be to expand the functionality of cement paste towards energy storage. To achieve this goal, one needs first to turn hardened cement paste, which is an oxide and therefore behaves as an electrical insulator, into a conductive material. In the present work, we report on the effect of adding carbon nanoparticles to cement. We show that the presence of such conductive filler allows us to turn hardened cement paste into a conductive material, with an electrical resistivity as low as a few. By means of statistical nano- and micro-indentation experiments, we demonstrate that the mechanical properties of carbon-loaded cement samples, remain comparable to that of pure cement, while adsorption experiments provides insights into their porosity at the nanoscale. Our results show that embedding conductive nanoparticles in cement paste is a viable approach for diversifying concrete properties, thus paving the way for engineering cement-based energy storage devices.

Short Bio: Roland Pellenq is Director of Research at CNRS, the French Government Agency for Scientific Research and a MIT Senior Research Scientist. He is a computational materials scientist with a strong interest in the physics and mechanics of micro- and nanoporous materials and confined fluids. He graduated in 1994 with a PhD in Chemical Physics from Imperial College London (UK) and received his Habilitation degree from the University of Orléans (France) in 2000. R. Pellenq’s research is dedicated to the development of bottom-up simulation approaches (starting at an atomistic level of description) for a large variety of critical problems in energy and environment, ranging from hydrogen and CH₄storage, CO₂ sequestration/fracking in shale gas to the stability of nuclear fuels and fundamentals of cement and concrete research. More recently R. Pellenq’s moved into the field of Urban Physics with the idea of applying atomistic concepts imported from Statistical Physics to cities and understand heat and flow at the city-scale and their link to city texture in the context of urban resilience to climate change. R. Pellenq is the author or co-author of 220+ papers published in major peer reviewed scientific journals. He is the co-founders and lead scientist of the Concrete Sustainability Hub, CSH@MIT, opened in 2009, an interdisciplinary research center dedicated to the reduction of the environmental footprint of the cement and concrete industry. He was hired as a MIT Senior Research Scientist in November 2011 and is the head of the MIT-CNRS-AMU joint laboratory “Multi-Scale Material Science for Energy and Environment” located on the MIT campus.