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Liberto T, Nenning A, Bellotto M, Dalconi MC, Dworschak D, Kalchgruber L, Robisson A, Valtiner M, Dziadkowiec J. Detecting Early-Stage Cohesion Due to Calcium Silicate Hydration with Rheology and Surface Force Apparatus. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:14988-15000. [PMID: 36426749 PMCID: PMC9730907 DOI: 10.1021/acs.langmuir.2c02783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 11/13/2022] [Indexed: 06/16/2023]
Abstract
Extremely robust cohesion triggered by calcium silicate hydrate (C-S-H) precipitation during cement hardening makes concrete one of the most commonly used man-made materials. Here, in this proof-of-concept study, we seek an additional nanoscale understanding of early-stage cohesive forces acting between hydrating model tricalcium silicate (C3S) surfaces by combining rheological and surface force measurements. We first used time-resolved small oscillatory rheology measurements (SAOSs) to characterize the early-stage evolution of the cohesive properties of a C3S paste and a C-S-H gel. SAOS revealed the reactive and viscoelastic nature of C3S pastes, in contrast with the nonreactive but still viscoelastic nature of the C-S-H gel, which proves a temporal variation in the cohesion during microstructural physicochemical rearrangements in the C3S paste. We further prepared thin films of C3S by plasma laser deposition (PLD) and demonstrated that these films are suitable for force measurements in the surface force apparatus (SFA). We measured surface forces acting between two thin C3S films exposed to water and subsequent in situ calcium silicate hydrate precipitation. With the SFA and SFA-coupled interferometric measurements, we resolved that C3S surface reprecipitation in water was associated with both increasing film thickness and progressively stronger adhesion (pull-off force). The lasting adhesion developing between the growing surfaces depended on the applied load, pull-off rate, and time in contact. These properties indicated the viscoelastic character of the soft, gel-like reprecipitated layer, pointing to the formation of C-S-H. Our findings confirm the strong cohesive properties of hydrated calcium silicate surfaces that, based on our preliminary SFA measurements, are attributed to sharp changes in the surface microstructure. In contact with water, the brittle and rough C3S surfaces with little contact area weather into soft, gel-like C-S-H nanoparticles with a much larger surface area available for forming direct contacts between interacting surfaces.
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Affiliation(s)
- Teresa Liberto
- Institute
of Materials Technology, Building Physics and Construction Ecology,
Faculty of Civil Engineering, Vienna University
of Technology, 1040 Vienna, Austria
| | - Andreas Nenning
- Institute
of Chemical Technologies and Analytics, Vienna Institute of Technology, 1060 Wien, Austria
| | | | - Maria Chiara Dalconi
- Department
of Geoscience and CIRCe Center, University
of Padua, 35131 Padova, Italy
| | - Dominik Dworschak
- Institute
of Applied Physics, Vienna Institute of
Technology, 1040 Wien, Austria
| | - Lukas Kalchgruber
- Institute
of Applied Physics, Vienna Institute of
Technology, 1040 Wien, Austria
| | - Agathe Robisson
- Institute
of Materials Technology, Building Physics and Construction Ecology,
Faculty of Civil Engineering, Vienna University
of Technology, 1040 Vienna, Austria
| | - Markus Valtiner
- Institute
of Applied Physics, Vienna Institute of
Technology, 1040 Wien, Austria
| | - Joanna Dziadkowiec
- Institute
of Applied Physics, Vienna Institute of
Technology, 1040 Wien, Austria
- NJORD Centre,
Department of Physics, University of Oslo, P.O. Box 1048, Oslo 0316, Norway
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Microstructure and Properties of C–S–H Synthesized in the Presence of Polycarboxylate Superplasticizer. ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2022. [DOI: 10.1007/s13369-022-07344-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Investigation of mechanisms of radiolytic H2 production in C-S-H: Influence of water content and radiation induced defects. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2021.109865] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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An Atomistic Model Describing the Structure and Morphology of Cu-Doped C-S-H Hardening Accelerator Nanoparticles. NANOMATERIALS 2022; 12:nano12030342. [PMID: 35159685 PMCID: PMC8839642 DOI: 10.3390/nano12030342] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 01/13/2022] [Accepted: 01/17/2022] [Indexed: 02/04/2023]
Abstract
Calcium silicate hydrate (C-S-H) is the main binding phase in Portland cement. The addition of C-S-H nanoparticles as nucleation seeds has successfully been used to accelerate the hydration process and the precipitation of binding phases either in conventional Portland cement or in alternative binders. Indeed, the modulation of the hydration kinetics during the early-stage dissolution-precipitation reactions, by acting on the nucleation and growth of binding phases, improves the early strength development. The fine-tuning of concrete properties in terms of compressive strength and durability by designed structural modifications can be achieved through the detailed description of the reaction products at the atomic scale. The nano-sized, chemically complex and structurally disordered nature of these phases hamper their thorough structural characterization. To this aim, we implement a novel multi-scale approach by combining forefront small-angle X-ray scattering (SAXS) and synchrotron wide-angle X-ray total scattering (WAXTS) analyses for the characterization of Cu-doped C-S-H nanoparticles dispersed in a colloidal suspension, used as hardening accelerator. SAXS and WAXTS data were analyzed under a unified modeling approach by developing suitable atomistic models for C-S-H nanoparticles to be used to simulate the experimental X-ray scattering pattern through the Debye scattering equation. The optimization of atomistic models against the experimental pattern, together with complementary information on the structural local order from 29Si solid-state nuclear magnetic resonance and X-ray absorption spectroscopy, provided a comprehensive description of the structure, size and morphology of C-S-H nanoparticles from the atomic to the nanometer scale. C-S-H nanoparticles were modeled as an assembly of layers composed of 7-fold coordinated Ca atoms and decorated by silicate dimers and chains. The structural layers are a few tens of nanometers in length and width, with a crystal structure resembling that of a defective tobermorite, but lacking any ordering between stacking layers.
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Çevirim-Papaioannou N, Androniuk I, Han S, Mouheb NA, Gaboreau S, Um W, Gaona X, Altmaier M. Sorption of beryllium in cementitious systems relevant for nuclear waste disposal: Quantitative description and mechanistic understanding. CHEMOSPHERE 2021; 282:131094. [PMID: 34470157 DOI: 10.1016/j.chemosphere.2021.131094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 05/28/2021] [Accepted: 06/01/2021] [Indexed: 06/13/2023]
Abstract
Beryllium has applications in fission and fusion reactors, and it is present in specific streams of radioactive waste. Accordingly, the environmental mobility of beryllium needs to be assessed in the context of repositories for nuclear waste. Although cement is widely used in these facilities, Be(II) uptake by cementitious materials was not previously investigated and was hence assumed negligible. Sorption experiments were performed under Ar-atmosphere. Ordinary Portland cement, low pH cement, calcium silicate hydrated (C-S-H) phases and the model system TiO2 were investigated. Sorption kinetics, sorption isotherms and distribution ratios (Rd, in kg⋅L-1) were determined for these systems. Molecular dynamics were used to characterize the surface processes driving Be(II) uptake. A strong uptake (5 ≤ log Rd ≤ 7) is quantified for all investigated cementitious systems. Linear sorption isotherms are observed over three orders of magnitude in [Be(II)]aq, confirming that the uptake is controlled by sorption processes and that solubility phenomena is not relevant within the investigated conditions. The analogous behaviour observed for cement and C-S-H support that the latter are the main sink of beryllium. The two step sorption kinetics is explained by a fast surface complexation process, followed by the slow incorporation of Be(II) in C-S-H. Molecular dynamics indicate that Be(OH)3- and Be(OH)42- are sorbed to the C-S-H surface through Ca-bridges. This work provides a comprehensive quantitative and mechanistic description of Be(II) uptake by cementitious materials, whose retention properties can be now reliably assessed for a wide range of boundary conditions of relevance in nuclear waste disposal.
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Affiliation(s)
- N Çevirim-Papaioannou
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.
| | - I Androniuk
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - S Han
- Division of Advanced Nuclear Engineering (DANE), Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, South Korea
| | - N Ait Mouheb
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - S Gaboreau
- BRGM Bureau de Recherches Géologiques et Minières, Orleans, France
| | - W Um
- Division of Advanced Nuclear Engineering (DANE), Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, South Korea
| | - X Gaona
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.
| | - M Altmaier
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
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Diaz Caselles L, Roosz C, Hot J, Blotevogel S, Cyr M. Immobilization of molybdenum by alternative cementitious binders and synthetic C-S-H: An experimental and numerical study. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 789:148069. [PMID: 34323832 DOI: 10.1016/j.scitotenv.2021.148069] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 05/09/2021] [Accepted: 05/23/2021] [Indexed: 06/13/2023]
Abstract
Excavation operations during construction produce millions of tons of soil sometimes with high leachable molybdenum (Mo) contents, that can lead to risks for both human health and the environment. It is therefore necessary to immobilize the Mo in excavated soils to reduce pollution and lower the costs of soil disposal. This paper studies the immobilization of Mo by three cementitious binders. To this end, one Ordinary Portland cement (OPC), one binder composed of 90% ground granulated blast furnace slag (GGBS) and 10% OPC, and one supersulfated GGBS binder were spiked with sodium molybdate at six different Mo concentrations from 0.005 wt% to 10 wt% before curing. In addition, to gain mechanistic insights, the capacity of synthetic calcium silicate hydrates (C-S-H) to immobilize Mo was studied. This study was completed by thermodynamic modeling to predict the immobilization of Mo at low Mo concentrations (<0.005 wt%). Paste leaching tests results showed that more than 74% of the initial Mo spike was immobilized by the three binders. The supersulfated GGBS binder consistently showed the highest retention levels (92.0 to 99.7%). The precipitation of powellite (CaMoO4) was the dominant mechanism of Mo retention in all binders and most leaching solutions were oversaturated with respect to powellite. Also, in C-S-H syntheses, Mo was largely immobilized (>95%) by the coprecipitation of powellite. Thermodynamic modeling was in good agreement with measured values when the equilibrium constant of powellite was modified to LogK = -7.2. This suggested that powellite is less stable in cementitious environments than would be expected from thermodynamic databases. Moreover, modeling showed that, for a solution at equilibrium with portlandite or C-S-H, the Mo concentration is limited to 1.7 mg/L by powellite precipitation. In contrast, for a solution saturated with respect to ettringite, the threshold concentration for powellite precipitation is 6.5 mg/L.
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Affiliation(s)
- Laura Diaz Caselles
- LMDC, INSA/UPS Génie Civil, 135 Avenue de Rangueil, 31077 Toulouse cedex 04, France.
| | - Cédric Roosz
- LMDC, INSA/UPS Génie Civil, 135 Avenue de Rangueil, 31077 Toulouse cedex 04, France
| | - Julie Hot
- LMDC, INSA/UPS Génie Civil, 135 Avenue de Rangueil, 31077 Toulouse cedex 04, France
| | - Simon Blotevogel
- LMDC, INSA/UPS Génie Civil, 135 Avenue de Rangueil, 31077 Toulouse cedex 04, France
| | - Martin Cyr
- LMDC, INSA/UPS Génie Civil, 135 Avenue de Rangueil, 31077 Toulouse cedex 04, France
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