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Concept

Silicate

Publications associées (31)

New tools for phase segmentation and denoising of analytical STEM data for enhanced chemical sensitivity, applied to Earth mantle research

Hui Chen, Hui Chen

This thesis is dedicated to developing innovative methodologies that improve elemental quantification in scanning transmission electron microscopy (STEM) using energy-dispersive X-ray spectroscopy (EDXS). The primary motivation stems from a geochemistry pr ...

EPFL2023

Atomistic modeling of C-S-H: bulk and surface

Ziga Casar

By replacing part of Portland cement with so-called supplementary cementitious materials (SCMs) it is possible to reduce the CO2 footprint of the cement industry. These SCMs are commonly limestone, calcined clay, slag and fly ash. While doing so the early ...

EPFL2023

The role of Zn in C-S-H atomic structure, nucleation and growth

Anna Morales Melgares

The most promising solution towards cementitious materials with a lower carbon footprint is the partial substitution of the clinker by supplementary cementitious materials (SCMs) such as fly ash, blast furnace slag, limestone and calcined clays. The produc ...

EPFL2023

Atomic-Level and Surface Structure of Calcium Silicate Hydrate Nanofoils

Karen Scrivener, Paul Bowen, Ziga Casar, Aslam Kunhi Mohamed

Deciphering the calcium silicate hydrate (C-S-H) surface is crucial for unraveling the mechanisms of cement hydration and property development. Experimental observations of C-S-H in cement systems suggest a surface termination which is fundamentally differ ...

AMER CHEMICAL SOC2023

Effect of alkali, aluminium and equilibration time on calcium-silicate-hydrates

Yu Yan, Yiru Yan

Calcium silicate hydrate (C-S-H) is the main hydration product in Portland and blended cements, and greatly affects durability and mechanical properties of the hydrated cement. In the presence of Al-rich supplementary cementitious materials (SCMs), C-(A-)S ...

EPFL2022

Effect of alkali hydroxide on calcium silicate hydrate (C-S-H)

Karen Scrivener, Émilie Michèle L'Hôpital, Yu Yan

This paper investigates the effect of KOH and NaOH on C-S-H structure and solubility. Both KOH and NaOH have a similar effect, they increase pH values and silicon concentrations, and decrease calcium concentrations. At higher alkali hydroxide concentration ...

Pergamon-Elsevier Science Ltd2022

Al uptake in calcium silicate hydrate and the effect of alkali hydroxide

Karen Scrivener, Yan Yan

The effect of Al and of pH on the structure of calcium silicate hydrate (C-S-H), the most important hydration product in Portland and blended cement, was studied at Ca/Si similar to 1.0. The presence of Al led to higher amounts of secondary phases, larger ...

Pergamon-Elsevier Science Ltd2022

Two-dimensional atomically bridged nanoporous silicate-based membranes for gas separation

Mostapha Dakhchoune

The synthesis of molecular-sieving two-dimensional zeolitic membranes by the assembly of crystalline building blocks without resorting to the secondary growth process is highly desirable. The precise pore size for molecular sieving, ultrathin thickness, an ...

EPFL2021

Reactive dicalcium silicate binders: Microstructure and transport properties

Adrian-Alexandru Pîrvan

The calcium silicate hydrates (C-S-H) are without doubt one of the most important hydration products in a hardened cement paste. Giving the complexity of the microstructure that forms by hydration of ordinary Portland cement (OPC) and the more recently use ...

EPFL2022

Towards implementing new isotopes for environmental research:Redetermination of the 32Si half-life

Mario Aaron Veicht

The predicted climate changes on Earth will significantly impact the environment and human society. The climate patterns observed during the past centuries led to a better understanding of the driving forces for such changes. However, more studies using ne ...

EPFL2022

A long-term study on structural changes in calcium aluminate silicate hydrates

Christian Ludwig, Sonya Barzgar, Yu Yan

Production of blended cements in which Portland cement is combined with supplementary cementitious materials (SCM) is an effective strategy for reducing the CO2 emissions during cement manufacturing and achieving sustainable concrete production. However, t ...

SPRINGER2022

The effect of alkali hydroxides and equilibration time on Al uptake by calcium silicate hydrates (C-S-H)

Sonya Barzgar

Cement production accounts for approximately 8% of man-made CO2 emissions. Lowering these CO2 emissions is currently one of the most important and urgent research topics within the cement community. To reduce these emissions, the Portland cement (PC) is pa ...

EPFL2021

Multi-scale investigation on mechanical behavior and microstructural alteration of C-S-H in carbonated Alite paste

Karen Scrivener

Carbonation treatment is a promising option to enhance recycled concrete aggregate (RCA) quality and eventually improve concrete performance. This study investigated the multi-scale mechanical properties of calcium silicate hydrates (C-S-H) in a mature ali ...

Pergamon-Elsevier Science Ltd2021

Iron incorporation in synthetic precipitated calcium silicate hydrates

David Lyndon Emsley, Paul Bowen, Brennan James Walder, Jirawan Siramanont

Effect of Fe3+ on the precipitation of synthetic calcium silicate hydrates (C-S-H) under controlled conditions has been evaluated. Using extremely basic either initial calcium nitrate or sodium silicate solutions (pH > 11), incipient formation of ferrihydr ...

Pergamon-Elsevier Science Ltd2021

Structure-Property Relationships in Complex Materials by Combining Supervised and Unsupervised Machine Learning

Benjamin Aaron Helfrecht

The work presented in this thesis combines supervised and unsupervised machine learning to examine structure-property relationships in databases of materials. While either supervised learning or unsupervised learning alone can be a powerful tool for assess ...

EPFL2021

Strength-promoting mechanism of alkanolamines on limestone-calcined clay cement and the role of sulfate

Karen Scrivener, François Henri Avet, Xuerun Li, Wilasinee Hanpongpun, Hong Huang

This paper reports the strength-promoting mechanism of alkanolamines on limestone-calcined clay cement (LC3). The hydration kinetics, phase formation and microstructure of LC3 with triethanolamine (TEA) or triisopropanolamine (TIPA) were investigated. TEA ...

Pergamon-Elsevier Science Ltd2021

The effect of sodium hydroxide on Al uptake by calcium silicate hydrates (C S H)

Christian Ludwig, Sonya Barzgar

To reduce the CO2 emissions from cement production, Portland cement (PC) is partially replaced by supplementary cementitious materials (SCM). Reactions of SCM with PC during hydration leads to the formation of CSH with more silicon and aluminum than in PC, ...

2020

Porous granules by freeze granulation of Pickering emulsions stabilized with halloysite particles

Paul Bowen

Pickering emulsions stabilized with a natural silicate mineral, halloysite, were dried by freeze granulation in order to prepare porous granules. Different formulations were studied, by varying the pH of the suspension, the ionic strength and with the addi ...

ELSEVIER2020

Advanced Computational Methods for NMR Crystallography

Albert Hofstetter

Knowledge of the atomic-level structure is key to understanding and predicting properties of materials. X-ray diffraction (XRD) is the methods of choice for structures containing well-defined long-range order. However, many materials contain various degree ...

EPFL2019

Advances in understanding cement hydration mechanisms

Karen Scrivener, Alexandre Reda Constantin William Caleb Ouzia, Aslam Kunhi Mohamed

Progress in understanding hydration mechanisms of alite and Portland cement is reviewed. Up to the end of the induction period, dissolution rates determined by the undersaturation of the solution dominate the reaction, but, better understanding is needed a ...

Pergamon-Elsevier Science Ltd2019