Project

Back to overview

Stable phase composition in novel cementitious systems: C-A-S-H

Applicant Lothenbach Barbara
Number 130419
Funding scheme Sinergia
Research institution Abteilung Beton / Bauchemie EMPA
Institution of higher education Swiss Federal Laboratories for Materials Science and Technology - EMPA
Main discipline Material Sciences
Start/End 01.11.2010 - 31.10.2014
Approved amount 919'148.00
Show all

All Disciplines (2)

Discipline
Material Sciences
Inorganic Chemistry

Keywords (6)

Cement; thermodynamic; C-S-H; supplementary cementitious materials; solubility; thermodynamic modelling

Lay Summary (English)

Lead
Lay summary
Concrete is the world's most durable, reliable and economical construction material, essential for the basic infrastructures that make our societies function smoothly. However, the production of cement, the key binding element in concrete, is responsible for roughly 5-8% of global man-made CO2, due to the very large use of concrete to build houses and infrastructures. For every tonne of Portland cement produced, 650-900 kg of CO2 is emitted amounting to more than 2 million tonnes worldwide The largest potential for CO2 reduction lies in (a) reducing the clinker content e.g. by the addition of limestone or (b) using supplementary cementitious materials (SCMs). The use of SCMs such as blast furnace slags resulting from steel production or fly ash from coal combustions, represent a viable al-ternative to Portland cements and are means to utilize by-products of industrial manufacturing proc-esses. The use of such SCMs is hindered by the fact that novel, low-CO2 cementitious materials will inevitably have different chemistry and will form different solids during hydration than Portland ce-ments and therefore perform and behave differently in concrete. The single most important phase in cements based on silica-rich SCMs is the calcium silicate hydrate phase (C-S-H). The C-S-H in such systems is dramatically different to C-S-H in Portland cements; it will exhibit a low Ca/Si ratio, will have different space filling properties and also show an increased incorporation of ions such as aluminum (C-A-S-H) or alkalis. This is critical for the mechanical properties and durability of the concrete. Our knowledge about the structure, composition and the properties of such a low Ca/Si C-A-S-H is insuffi-cient. This project aims to understand the change in properties of silica-rich C-S-H in presence of silica-rich supplementary cementitious materials. We will develop a thermodynamic model for C(-A)-S-H, N/K-A-S-H gel in cementitious systems based on i) the structural information and surface properties of C-(A)-S-H from atomistic simulations, ii) experimental data on solubility of C(-A)-S-H in the presence of al-kali, iii) experimental data on solubility of C(-A)-S-H in the presence of sulfate, carbonate and chlorides and iv) detailed spectroscopic characterization and investigation of the homogeneity of the solid phases.We will apply the thermodynamic model to predict the stable phase assemblage, its volume properties and porosity in cement. The development of such generic thermodynamic models is an indispensable step toward a better fundamental understanding of cementitious systems based on SCMs.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Calcium silicate hydrates: Solid and liquid phase composition
Lothenbach Barbara, Nonat André (2015), Calcium silicate hydrates: Solid and liquid phase composition, in Cement and Concrete Research, 78, 57-70.
Composition of C-S-H in pastes with increasing levels of silica fume addition
Rossen J. E., Lothenbach B., Scrivener K. L. (2015), Composition of C-S-H in pastes with increasing levels of silica fume addition, in CEMENT AND CONCRETE RESEARCH, 75, 14-22.
Composition-solubility-structure relationships in calcium (alkali) aluminosilicate hydrate (C-(N,K-)A-S-H)
Myers Rupert J., Myers Rupert J., L'Hôpital Emilie, Provis John L., Lothenbach Barbara (2015), Composition-solubility-structure relationships in calcium (alkali) aluminosilicate hydrate (C-(N,K-)A-S-H), in Dalton Transactions, 44(30), 13530-13544.
Effect of temperature and aluminium on calcium (alumino)silicate hydrate chemistry under equilibrium conditions
Myers Rupert J., L'Hopital Emilie, Provis John L., Lothenbach Barbara (2015), Effect of temperature and aluminium on calcium (alumino)silicate hydrate chemistry under equilibrium conditions, in Cement and Concrete Research, 68, 83-93.
From C–S–H to C–A–S–H: Experimental study and thermodynamic modelling
Haas Jeremy, Nonat André (2015), From C–S–H to C–A–S–H: Experimental study and thermodynamic modelling, in Cement and Concrete Research, 68, 124-138.
Incorporation of aluminium in calcium-silicate-hydrates
L'Hôpital E., Lothenbach B., Le Saout G., Kulik D., Scrivener K. (2015), Incorporation of aluminium in calcium-silicate-hydrates, in Cement and Concrete Research, 75, 91-103.
Magnesium and calcium silicate hydrates
Lothenbach B., Nied D., L'Hôpital E., Achiedo G., Dauzères A. (2015), Magnesium and calcium silicate hydrates, in Cement and Concrete Research, 77, 60-68.
Thermodynamic modelling of alkali-activated slag cements
Myers Rupert J., Lothenbach Barbara, Bernal Susan A., Provis John L. (2015), Thermodynamic modelling of alkali-activated slag cements, in Applied Geochemistry, 61, 233-247.
Intrinsic Acidity of Surface Sites in Calcium Silicate Hydrates and Its Implication to Their Electrokinetic Properties
Churakov Sergey V., Labbez Christophe, Pegado Luis, Sulpizi Marialore (2014), Intrinsic Acidity of Surface Sites in Calcium Silicate Hydrates and Its Implication to Their Electrokinetic Properties, in JOURNAL OF PHYSICAL CHEMISTRY C, 118(22), 11752-11762.
Mechanism of aluminium incorporation into C-S-H from ab initio calculations
Pegado Luis, Labbez Christophe, Churakov Sergey V. (2014), Mechanism of aluminium incorporation into C-S-H from ab initio calculations, in JOURNAL OF MATERIALS CHEMISTRY A, 2(10), 3477-3483.
Solvation and ion-pairing properties of the aqueous sulfate anion: explicit versus effective electronic polarization
Pegado Luis, Marsalek Ondrej, Jungwirth Pavel, Wernersson Erik (2012), Solvation and ion-pairing properties of the aqueous sulfate anion: explicit versus effective electronic polarization, in Phys. Chem. Chem. Phys., 14, 10248-10257.

Collaboration

Group / person Country
Types of collaboration
University of Aarhus Denmark (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel
University of Sheffield Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel
University of Leeds Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
CEA Marcoule France (Europe)
- in-depth/constructive exchanges on approaches, methods or results

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
34th Cement and Concrete Science Conference Talk given at a conference Magnesium and calcium silicate hydrates 14.09.2014 Sheffield, Great Britain and Northern Ireland Lothenbach Barbara; L'Hôpital Emilie;
NUWCEM 2nd International Symposium on Cement-Based Materials for Nuclear Wastes Talk given at a conference Calcium and magnesium silicate hydrates 03.06.2014 Avignon, France Lothenbach Barbara; L'Hôpital Emilie;
NUWCEM 2nd International Symposium on Cement-Based Materials for Nuclear Wastes Talk given at a conference Synthesis and characterisation of pure C(-A)-S-H phases 03.06.2014 Avignon, France Lothenbach Barbara; Scrivener Karen; L'Hôpital Emilie;
Workshop on Calcium Silicates Containing Aluminium: C-A-S-H Talk given at a conference Aluminium uptake in C-S-H and influence of alkali 05.05.2014 Dübendorf, Switzerland Scrivener Karen; L'Hôpital Emilie; Lothenbach Barbara;
Workshop on Calcium Silicates Containing Aluminium: C-A-S-H Talk given at a conference Free energy of C-S-H-ion interactions from ab initio simulations 05.05.2014 Dübendorf, Switzerland Churakov Sergey;
Workshop on Calcium Silicates Containing Aluminium: C-A-S-H Talk given at a conference Study of C-A-S-H by SEM-EDX and STEM in pastes of water/binder = 0.4. 05.05.2014 Dübendorf, Switzerland Scrivener Karen; Rossen John; Lothenbach Barbara;
Workshop on Calcium Silicates Containing Aluminium: C-A-S-H Talk given at a conference Effect of temperature on OPC-silica fume mixtures 05.05.2014 Dübendorf, Switzerland Lothenbach Barbara;
Workshop on Calcium Silicates Containing Aluminium: C-A-S-H Talk given at a conference Effect of temperature and aluminium on calcium aluminosilicate hydrate chemistry under equilibrium conditions 05.05.2014 Dübendorf, Switzerland Lothenbach Barbara; L'Hôpital Emilie;
Workshop on Calcium Silicates Containing Aluminium: C-A-S-H Talk given at a conference C-A-S-H: mechanism of Al incorporation and the road to multi-scale molecular modelling of ion sorption 05.05.2014 Dübendorf, Switzerland Pegado Luis;
Workshop on Calcium Silicates Containing Aluminium: C-A-S-H Talk given at a conference Anion uptake by C-(A-)S-H: experimental results and thermodynamic modelling 05.05.2014 Dübendorf, Switzerland Nonat Andre; Plusquellec Gilles;
Workshop on Calcium Silicates Containing Aluminium: C-A-S-H Talk given at a conference From C-S-H to C-A-S-H: experimental study and thermodynamic modelling 05.05.2014 Dübendorf, Switzerland Nonat Andre;
Transcend Conference Talk given at a conference Aluminium uptake in in calcium silicate hydrate 03.11.2013 Guilford, Great Britain and Northern Ireland L'Hôpital Emilie; Lothenbach Barbara; Scrivener Karen;
Transcend conference Poster Stability of C-A-S-H in blended cement pastes. 03.11.2013 Guilford, Great Britain and Northern Ireland Lothenbach Barbara; Scrivener Karen; Rossen John;
Transcend Conference Talk given at a conference Aluminium Substitution in C-S-H: ab initio Calculations 03.11.2013 Guilford, Great Britain and Northern Ireland Churakov Sergey; Pegado Luis;
Transcend conference Poster anions uptake by calcium silicate hydrates: influence of type of counter-ions and temperature 03.11.2013 Guilford, Great Britain and Northern Ireland Lothenbach Barbara; Nonat Andre; Plusquellec Gilles;
European Materials Research Society Meeting Poster Aluminium Substitution in C-S-H: ab initio Calculations 16.09.2013 Warsaw, Poland Churakov Sergey; Pegado Luis;
14th Euroseminar Applied to Building Materials (EMABM 2013) Individual talk Optimising the experimental conditions for analysing calcium silicate hydrates in a white Portland cement paste 10.06.2013 Helsingor, Denmark Scrivener Karen; Rossen John; Lothenbach Barbara;
XIVèmes journées de l’Ecole Doctoral Carnot-Pasteur Talk given at a conference Adsorption d’anions par le silicate de calcium hydraté 30.05.2013 Dijon, France Nonat Andre; Plusquellec Gilles;
3rd International Workshop on Mechanisms and Modelling of Waste/Cement Interactions Poster Aluminium and alkali uptake in in calcium silicate hydrate 06.05.2013 Gent, Belgium Lothenbach Barbara; L'Hôpital Emilie; Scrivener Karen;
3rd International Workshop on Mechanisms and modelling of waste/cement interactions Talk given at a conference Understanding ion adsorption by C-S-H: From ab initio simulations to thermodynamic equilibrium 06.05.2013 Ghent, Belgium Pegado Luis; Churakov Sergey;
32nd Cement and Concrete Science Conference Poster Anion uptake by calcium silicate hydrate 17.09.2012 Queen’s University Belfast, Great Britain and Northern Ireland Plusquellec Gilles; Nonat Andre;


Self-organised

Title Date Place
Molecular modelling workshop 20.02.2013 Univerity of Dijon, Dijon, France
C-S-H meso to atomistic structure 04.10.2011 Lausanne, Switzerland, Switzerland

Associated projects

Number Title Start Funding scheme
117605 The fate of iron during the hydration of cement 01.02.2008 Project funding (Div. I-III)
119957 Modelling and Experimental Study of Hydration, Early Age Shrinkage and Expansion in Cementitious Systems 01.04.2008 Project funding (Div. I-III)
139157 Nanoscale Mapping of Mechanical Properties (n-MPM) 01.11.2012 R'EQUIP
165548 Dissolution, growth and toxic ion uptake at phyllosilicate surfaces: Coupling atomistic interactions at the mineral-water interface with Kinetic Monte Carlo model. 01.01.2017 Project funding (Div. I-III)
132559 The fate of iron during the hydration of cement - II 01.02.2011 Project funding (Div. I-III)
150638 Empa/Eawag NMR Spektrometer, Aufrüstung mit einem Probenkopf des Typs Prodigy Cryo 01.04.2014 R'EQUIP
169014 Effect of aluminum on C-S-H structure, stability and solubility 01.03.2017 Project funding (Div. I-III)

Abstract

The production of cement is responsible for 5-8% of global man-made CO2. The replacement of Portland cement by supplementary cementitious materials (SCM) offers the highest potential to reduce these CO2 emissions. The industrial application of SCMs based materials is hindered by the fact that novel, low-CO2 cementitious materials have different chemical composition and will form other hydrates than Portland cements. In the presence of silica rich SCMs, such as blast furnace slag or fly ash, calcium silicate hydrate (C-S-H) with a low Ca/Si ratio is the most important hydrate that forms. However, reliable thermodynamic models and experimental data for C-S-H with low Ca/Si ratio are not available.This project aims to investigate the solubility, structure, and composition of C(-A)-S-H gel as a function of different parameters such as Ca/Si ratio, pH, aluminum, alkali and anion content. We will develop a thermodynamic model for C(-A)-S-H, N/K-A-S-H gel in cementitious systems based on 1.the structural information and surface properties of C-(A)-S-H from atomistic simulations; 2.experimental data on solubility of C(-A)-S-H in the presence of alkali 3.experimental data on solubility of C(-A)-S-H in the presence of anionic species such as sulfate, carbonate and chlorides4.detailed spectroscopic characterization and investigation of the homogeneity of the solid phasesNewly developed modeling tools provide a solid scientific background for predictions and testing of novel environmentally friendly and cost efficient cementitious materials. These modeling tools will enable us in the future to predict the kind, amount and volume of hydration products also in silica-rich cementitious systems. The ability to calculate the porosity of a specific system is a starting-point to assess the potential of this system. In addition, the coupling of thermodynamic modeling with microstructural modeling will allow to predict mechanical and transport properties of cementitious system. The cutting edge modeling expertise and experimental knowledge required for the project success are not available within a single research group or university. Therefore we embark on interdisciplinary collaboration between world recognized experimental and modeling research groups working in the field of cement chemistry. Molecular modeling groups in PSI and ICB will closely collaborate with experimentalist in EMPA, EPFL and ICB. Atomistic scale system understanding and experimental data will back up the geochemical modeling expertise at EMPA and PSI.
-