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Thomas Young Centre Soiree:Katerina Ioannidou (Montpellier) / Tulio Honofrio de Faria (Paris) - “Multiscale modelling of cementitious materials”

Date(s): 23 May 2019
Time: 16:00 - 19:30
Location: Arts One Lecture Theatre, Mile End Campus, Queen Mary University of London
Details:
Katerina Ioannidou
Katerina Ioannidou
On Thursday 23rd May we will have a Thomas Young Centre soiree at QMUL on Cementitious Materials, with two world-leading modellers working in this area, Dr. Katerina Ioannidou (University of Montpellier) and Prof. Tulio Honofrio de Faria (École Normale Supérieure Paris-Saclay).

They will present their recent work on multiscale modelling of cementitious materials (title of the talk and abstract below).

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TYC SOIREE

Multiscale modelling of cementitious materials


SPEAKERS

Dr. Katerina Ioannidou, University of Montpellier

Prof. Tulio Honofrio de Faria, École Normale Supérieure Paris-Saclay

Followed by a reception

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Dr. Katerina Ioannidou

“Multiscale modeling of cement paste: texture, mechanics, durability and new functionalities”

Cement is a multiscale porous material, widely produced, more than any other synthetic material on Earth. In this talk, I will present a multiscale bottom-up approach for cement and specifically for calcium-silicate hydrate (C-S-H) that is the most abundant phase of cement. During cement hydration C-S-H nano-scale particles precipitate in the pore solution and form a cohesive gel that is the main binding agent in cement and concrete, crucial for the strength and the long-term evolution of the material. Even more than the molecular structure of C-S-H particles, the C-S-H mesoscale texture over hundreds of nanometers plays a crucial role for material properties. We use a statistical physics framework for aggregating nanoparticles and numerical simulations to obtain a first, to our knowledge, quantitative model for such a complex amorphous material. Our approach is based on precipitation of colloidal particles interacting with effective potentials associated to the chemical environment. The effective potential can be calculated from atomistic models of C-S-H and are corroborated by experiments. This multiscale informed modelling approach generates realistic micron scale textures in terms of pore size distributions and solid volume fractions and allows to calculate mechanical properties. The extensive comparison with experiments ranging from small-angle neutron scattering, EM imaging, adsorption/desorption of N2, and water to nano-indentation provides new fundamental insights into the microscopic origin of the cement properties measured. Our results provide a quantitative insight into how the heterogeneities developed during the early stages of hydration persist in the structure of C-S-H and impact the mechanical performance of the hardened cement paste. Moreover, this approach allowed to address durability issues on cement such as freeze-thaw and alkali-silica reaction damage leading to the formation of cracks and fractures. If time permits, I will discuss our recent results on turning cement into a capacitor for energy storage.

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Professor Tulio Honorio

“Water in cement-based materials”

Cement-based materials are complex ageing materials in which hydrates (i.e. the phases resulting from cement hydration processes) function as a glue, making a complex fluid (fresh paste or fresh concrete) turn into a solid, resistant material.

The interactions of hydrates with water are at the heart of critical features of cement-based material behavior such as its strength, durability, volume stability and confining capacity, as well as behaviors such as autogenous shrinkage, hysteresis and creep.

In this talk, recent results of ongoing projects on

i. the volume stability and elastic properties of hydrates (C-S-H and AF-phases),
ii. the pore solution and electromagnetic properties of cement-based materials

are presented in a multiscale modelling approach informed by the molecular scale. The results are used to reduce the empirism of model predicting concrete behavior and give insights on how to design cement-based materials with performance specifications.
Contact: Devis Di Tommaso
Email: d.ditommaso@qmul.ac.uk

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