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Xin Z, Zhang Y, Hou D, Sun H, Ding Z, Wang P, Wang M, Wang X, Xu Q, Guan J, Yang J, Liu Y, Zhang L. Atomic Insights into the Relationship between Molecular Structure and Dispersion Performance of Phenyl Polymer on Graphene Oxide. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:413-425. [PMID: 38133590 DOI: 10.1021/acs.langmuir.3c02648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
The adsorption of organic polymers onto the surface of graphene oxide is known to improve its dispersibility in cement-based materials. However, the mechanism of this improvement at the atomic level is not yet fully understood. In this study, we employ a combination of DFT static calculation and umbrella sampling to explore the reactivity of polymers and investigate the effects of varying amounts of phenyl groups on their adsorption capacity on the surface of graphene oxide. Quantitative analysis is utilized to study the structural reconstruction and charge transfer caused by polymers from multiple perspectives. The interfacial reaction between the polymer and graphene oxide surface is further clarified, indicating that the adsorption process is promoted by hydrogen bond interactions and π-π stacking effects. This study sheds light on the adsorption mechanism of polymer-graphene oxide systems and has important implications for the design of more effective graphene oxide dispersants at the atomic level.
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Affiliation(s)
- Zhaorui Xin
- Department of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China
| | - Yue Zhang
- Department of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China
| | - Dongshuai Hou
- Department of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China
| | - Huiwen Sun
- Department of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China
| | - Zhiheng Ding
- Department of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China
| | - Pan Wang
- Department of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China
| | - Muhan Wang
- Department of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China
| | - Xinpeng Wang
- Department of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China
| | - Qingqing Xu
- Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Jing Guan
- School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao 266033, China
| | - Jiayi Yang
- College of Materials Design and Engineering, Beijing Institute of Fashion and Technology, Beijing 100029, China
| | - Yingchun Liu
- College of Materials Design and Engineering, Beijing Institute of Fashion and Technology, Beijing 100029, China
| | - Liran Zhang
- College of Materials Design and Engineering, Beijing Institute of Fashion and Technology, Beijing 100029, China
- Department of Chemical Engineering, China University of Mining & Technology, Beijing 100083, China
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2
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Yang F, Cui Y, She A, Hai R, Zhu Z. Molecular Dynamics Simulation of Silane Inserted CSH Nanostructure. MATERIALS (BASEL, SWITZERLAND) 2023; 17:149. [PMID: 38204002 PMCID: PMC10780238 DOI: 10.3390/ma17010149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 12/21/2023] [Accepted: 12/25/2023] [Indexed: 01/12/2024]
Abstract
Herein, the toughening mechanism and effects of 3-(aminopropyl)triethoxysilane (3-APTES) intercalation in calcium-silicate-hydrate (CSH) structures were investigated through molecular dynamics simulations. CSH established a model using 11 Å-tobermorite to simulate the tensile properties, toughness, adsorption energy, average orientation displacement and radial distribution function of 3-APTES intercalation at different Ca/Si ratios under conditions of a CVFF force field, an NVT system, and 298 K temperature. Simulation results demonstrate that 3-APTES alters the fracture process of CSH and effectively enhances its tensile properties and toughness. The presence of 3-APTES molecules increases the energy required to destroy CSH, thereby increasing the adsorption energy of CSH crystals. Furthermore, 3-APTES molecules effectively increase the atom density within the CSH structure. As the Ca/Si ratio increases, Ca-O bond formation is enhanced, with noticeable aggregation occurring because of modification by 3-APTES within the CSH structure. This study found that 3-APTES organic compounds can effectively improve the tensile, toughness, adsorption and other properties of the CSH structure, and further improve the microstructure of CSH.
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Affiliation(s)
- Fei Yang
- School of Architectural and Civil Engineering, Zhongyuan University of Technology, Zhengzhou 450007, China; (Y.C.); (R.H.)
| | - Yangyang Cui
- School of Architectural and Civil Engineering, Zhongyuan University of Technology, Zhengzhou 450007, China; (Y.C.); (R.H.)
| | - Anming She
- Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, School of Materials Science and Engineering, Tongji University, Shanghai 201804, China;
| | - Ran Hai
- School of Architectural and Civil Engineering, Zhongyuan University of Technology, Zhengzhou 450007, China; (Y.C.); (R.H.)
| | - Zheyu Zhu
- School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng 224051, China;
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3
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Li X, Zhang H, Zhan H, Tang Y. Structural and Mechanical Properties of Doped Tobermorite. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2279. [PMID: 37630864 PMCID: PMC10459530 DOI: 10.3390/nano13162279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 07/29/2023] [Accepted: 08/02/2023] [Indexed: 08/27/2023]
Abstract
As calcium silicate hydrate (C-S-H) is the main binding phase in concrete, understanding the doping behavior of impurity elements in it is important for optimizing the structure of cementitious materials. However, most of the current studies focus on cement clinker, and the doping mechanism of impurity elements in hydrated calcium silicate is not yet fully understood. The hydrated calcium silicate component is complex, and its structure is very similar to that of the tobermorite mineral family. In this study, the effects of three different dopants (Mg, Sr and Ba) on a representing structure of C-S-H-tobermorite-was systematically explored using densify functional theory (DFT) calculations. The calculations show that Mg doping leads to a decrease in lattice volume and causes obvious structure and coordination changes of magnesium-oxygen polyhedra. This may be the reason why high formation energy is required for the Mg-doped tobermorite. Meanwhile, doping only increases the volume of the Sr- and Ba-centered oxygen polyhedra. Specifically, the Mg-doped structure exhibits higher chemical stability and shorter interatomic bonding. In addition, although Mg doping distorts the structure, the stronger chemical bonding between Mg-O atoms also improves the compressive (~1.99% on average) and shear resistance (~2.74% on average) of tobermorillonite according to the elastic modulus and has less effect on the anisotropy of the Young's modulus. Our results suggest that Mg doping is a promising strategy for the optimized structural design of C-S-H.
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Affiliation(s)
- Xiaopeng Li
- School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang 621010, China;
| | - Hongping Zhang
- School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang 621010, China;
- School of Mechanical Engineering, Institute for Advanced Study, Chengdu University, Chengdu 610106, China
| | - Haifei Zhan
- College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China;
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology (QUT), Brisbane 4001, Australia
| | - Youhong Tang
- Institute for NanoScale Science and Technology, College of Science and Engineering, Flinders University, Adelaide 5042, Australia
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4
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Kai MF, Li G, Yin BB, Akbar A. Aluminum-induced structure evolution and mechanical strengthening of calcium silicate hydrates: an atomistic insight. CONSTRUCTION AND BUILDING MATERIALS 2023; 393:132120. [DOI: 10.1016/j.conbuildmat.2023.132120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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5
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Geng G, Shi Z, Leemann A, Glazyrin K, Kleppe A, Daisenberger D, Churakov S, Lothenbach B, Wieland E, Dähn R. Mechanical behavior and phase change of alkali-silica reaction products under hydrostatic compression. ACTA CRYSTALLOGRAPHICA SECTION B, STRUCTURAL SCIENCE, CRYSTAL ENGINEERING AND MATERIALS 2020; 76:674-682. [PMID: 32831286 DOI: 10.1107/s205252062000846x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 06/24/2020] [Indexed: 06/11/2023]
Abstract
Alkali-silica reaction (ASR) causes severe degradation of concrete. The mechanical property of the ASR product is fundamental to the multiscale modeling of concrete behavior over the long term. Despite years of study, there is a lack of consensus regarding the structure and elastic modulus of the ASR product. Here, ASR products from both degraded field infrastructures and laboratory synthesis were investigated using high-pressure X-ray diffraction. The results unveiled the multiphase and metastable nature of ASR products from the field. The dominant phase undergoes permanent phase change via collapsing of the interlayer region and in-planar glide of the main layer, under pressure >2 GPa. The bulk moduli of the low- and high-pressure polymorphs are 27±3 and 46±3 GPa, respectively. The laboratory-synthesized sample and the minor phase in the field samples undergo no changes of phase during compression. Their bulk moduli are 35±2 and 76±4 GPa, respectively. The results provide the first atomistic-scale measurement of the mechanical property of crystalline ASR products.
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Affiliation(s)
- Guoqing Geng
- Laboratory of Waste Management, Paul Scherrer Institut, OHLD/004, Villigen, Aargau 5232, Switzerland
| | - Zhenguo Shi
- Laboratory for Concrete and Construction Chemistry, Swiss Federal Laboratories for Materials Science and Technology (Empa), Dübendorf, 8600, Switzerland
| | - Andreas Leemann
- Laboratory for Concrete and Construction Chemistry, Swiss Federal Laboratories for Materials Science and Technology (Empa), Dübendorf, 8600, Switzerland
| | - Konstantin Glazyrin
- Photon Sciences, Deutsches Elektronen-Synchrotron (DESY), Hamburg, D-22603, Germany
| | - Annette Kleppe
- Diamond Light Source, Harwell Science and Innovation Campus, Fermi Ave, Didcot, OX11 0DE, United Kingdom
| | - Dominik Daisenberger
- Diamond Light Source, Harwell Science and Innovation Campus, Fermi Ave, Didcot, OX11 0DE, United Kingdom
| | - Sergey Churakov
- Laboratory of Waste Management, Paul Scherrer Institut, OHLD/004, Villigen, Aargau 5232, Switzerland
| | - Barbara Lothenbach
- Laboratory for Concrete and Construction Chemistry, Swiss Federal Laboratories for Materials Science and Technology (Empa), Dübendorf, 8600, Switzerland
| | - Erich Wieland
- Laboratory of Waste Management, Paul Scherrer Institut, OHLD/004, Villigen, Aargau 5232, Switzerland
| | - Rainer Dähn
- Laboratory of Waste Management, Paul Scherrer Institut, OHLD/004, Villigen, Aargau 5232, Switzerland
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6
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Kunhi Mohamed A, Moutzouri P, Berruyer P, Walder BJ, Siramanont J, Harris M, Negroni M, Galmarini SC, Parker SC, Scrivener KL, Emsley L, Bowen P. The Atomic-Level Structure of Cementitious Calcium Aluminate Silicate Hydrate. J Am Chem Soc 2020; 142:11060-11071. [PMID: 32406680 DOI: 10.1021/jacs.0c02988] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Despite use of blended cements containing significant amounts of aluminum for over 30 years, the structural nature of aluminum in the main hydration product, calcium aluminate silicate hydrate (C-A-S-H), remains elusive. Using first-principles calculations, we predict that aluminum is incorporated into the bridging sites of the linear silicate chains and that at high Ca:Si and H2O ratios, the stable coordination number of aluminum is six. Specifically, we predict that silicate-bridging [AlO2(OH)4]5- complexes are favored, stabilized by hydroxyl ligands and charge balancing calcium ions in the interlayer space. This structure is then confirmed experimentally by one- and two-dimensional dynamic nuclear polarization enhanced 27Al and 29Si solid-state NMR experiments. We notably assign a narrow 27Al NMR signal at 5 ppm to the silicate-bridging [AlO2(OH)4]5- sites and show that this signal correlates to 29Si NMR signals from silicates in C-A-S-H, conflicting with its conventional assignment to a "third aluminate hydrate" (TAH) phase. We therefore conclude that TAH does not exist. This resolves a long-standing dilemma about the location and nature of the six-fold-coordinated aluminum observed by 27Al NMR in C-A-S-H samples.
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Affiliation(s)
- Aslam Kunhi Mohamed
- Laboratory of Construction Materials, Institut des Matériaux, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.,Institute for Building Materials, Department of Civil, Environmental and Geomatic Engineering, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Pinelopi Moutzouri
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Pierrick Berruyer
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Brennan J Walder
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Jirawan Siramanont
- Laboratory of Construction Materials, Institut des Matériaux, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.,SCG CEMENT Co., Ltd., Saraburi 18260, Thailand
| | - Maya Harris
- Laboratory of Construction Materials, Institut des Matériaux, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Mattia Negroni
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Sandra C Galmarini
- Building Energy Materials and Components, EMPA, CH-8600 Dübendorf, Switzerland
| | - Stephen C Parker
- Computational Solid State Chemistry Group, Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K
| | - Karen L Scrivener
- Laboratory of Construction Materials, Institut des Matériaux, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Lyndon Emsley
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Paul Bowen
- Laboratory of Construction Materials, Institut des Matériaux, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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7
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Pan SY, Lai B, Ren Y. Mechanistic insight into mineral carbonation and utilization in cement-based materials at solid-liquid interfaces. RSC Adv 2019; 9:31052-31061. [PMID: 35529403 PMCID: PMC9072294 DOI: 10.1039/c9ra06118e] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 09/25/2019] [Indexed: 11/24/2022] Open
Abstract
In order to ensure the viability of CO2 mineralization and utilization using alkaline solid waste, a mechanistic understanding of reactions at mineral–water interfaces was required to control the reaction pathways and kinetics. In this study, we provided new information for understanding the reactions of CO2 mineralization and utilization at mineral–water interfaces. Here we have carried out high-energy synchrotron X-ray analyses to characterize the changes of mineral phases in petroleum coke fly ash during CO2 mineralization and their subsequent utilization as supplementary cementitious materials in cement mortars. The 2-D synchrotron patterns were converted to 1-D diffraction patterns and the results were then interpreted via the Rietveld refinement. The results indicated that there was a continuous source of calcium ions mainly due to the dissolution of CaO and Ca(OH)2 in fly ash. This would actually enhance the driving force of saturation index at the solid–fluid interfacial layer, and then could eventually result in the nucleation and growth of calcium carbonate (calcite) at the interface. A small quantity of CaSO4 (anhydrite) in fly ash was also dissolved and simultaneously converted into calcite. In addition, the calcium sulfate in fly ash would effectively prevent the early hydration of tricalcium aluminate in blended cement, and thus could avoid the negative impact on its strength development. The proposed reaction mechanisms were also qualitatively verified by X-ray fluorescence mapping and electron microscopy. These results would help to design efficient reactors and cost-effective processes for CO2 mineralization and utilization in the future. Synchrotron-based X-ray analyses for understanding the reactions at mineral–water interfaces for CO2 mineralization and utilization using petroleum coke fly ash.![]()
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Affiliation(s)
- Shu-Yuan Pan
- Department of Bioenvironmental Systems Engineering, National Taiwan University Taipei City 10617 Taiwan
| | - Barry Lai
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory Argonne IL 60439 USA
| | - Yang Ren
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory Argonne IL 60439 USA
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8
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Cuesta A, De la Torre ÁG, Santacruz I, Diaz A, Trtik P, Holler M, Lothenbach B, Aranda MAG. Quantitative disentanglement of nanocrystalline phases in cement pastes by synchrotron ptychographic X-ray tomography. IUCRJ 2019; 6:473-491. [PMID: 31098028 PMCID: PMC6503921 DOI: 10.1107/s2052252519003774] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 03/19/2019] [Indexed: 05/25/2023]
Abstract
Mortars and concretes are ubiquitous materials with very complex hierarchical microstructures. To fully understand their main properties and to decrease their CO2 footprint, a sound description of their spatially resolved mineralogy is necessary. Developing this knowledge is very challenging as about half of the volume of hydrated cement is a nanocrystalline component, calcium silicate hydrate (C-S-H) gel. Furthermore, other poorly crystalline phases (e.g. iron siliceous hydrogarnet or silica oxide) may coexist, which are even more difficult to characterize. Traditional spatially resolved techniques such as electron microscopy involve complex sample preparation steps that often lead to artefacts (e.g. dehydration and microstructural changes). Here, synchrotron ptychographic tomography has been used to obtain spatially resolved information on three unaltered representative samples: neat Portland paste, Portland-calcite and Portland-fly-ash blend pastes with a spatial resolution below 100 nm in samples with a volume of up to 5 × 104 µm3. For the neat Portland paste, the ptychotomographic study gave densities of 2.11 and 2.52 g cm-3 and a content of 41.1 and 6.4 vol% for nanocrystalline C-S-H gel and poorly crystalline iron siliceous hydrogarnet, respectively. Furthermore, the spatially resolved volumetric mass-density information has allowed characterization of inner-product and outer-product C-S-H gels. The average density of the inner-product C-S-H is smaller than that of the outer product and its variability is larger. Full characterization of the pastes, including segmentation of the different components, is reported and the contents are compared with the results obtained by thermodynamic modelling.
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Affiliation(s)
- Ana Cuesta
- Departamento de Química Inorgánica, Cristalografía y Mineralogía, Universidad de Málaga, 29071-Malaga, Spain
| | - Ángeles G. De la Torre
- Departamento de Química Inorgánica, Cristalografía y Mineralogía, Universidad de Málaga, 29071-Malaga, Spain
| | - Isabel Santacruz
- Departamento de Química Inorgánica, Cristalografía y Mineralogía, Universidad de Málaga, 29071-Malaga, Spain
| | - Ana Diaz
- Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Pavel Trtik
- Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
- Faculty of Civil Engineering, Czech Technical University in Prague, 166 29 Prague, Czech Republic
| | - Mirko Holler
- Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Barbara Lothenbach
- EMPA, Laboratory for Concrete and Construction Chemistry, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland
| | - Miguel A. G. Aranda
- Departamento de Química Inorgánica, Cristalografía y Mineralogía, Universidad de Málaga, 29071-Malaga, Spain
- ALBA Synchrotron, Carrer de la Llum 2-26, E-08290 Cerdanyola del Vallès, Barcelona, Spain
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9
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Jiang J, Yan Y, Hou D, Yu J. Understanding the deformation mechanism and mechanical characteristics of cementitious mineral analogues from first principles and reactive force field molecular dynamics. Phys Chem Chem Phys 2018; 20:13920-13933. [PMID: 29744517 DOI: 10.1039/c7cp08640g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this paper, first principles and reactive force field molecular dynamics were utilized to study the mechanical properties of tobermorite 9 Å, tobermorite 11 Å and jennite. These are essential minerals in cement chemistry. The mechanical properties calculated by the first-principle method match well with previous experimental results, pointing to the introduction of vdW dispersion-type forces as able to improve the precision. The calculated elastic constants of the three minerals confirm anisotropic mechanical behavior of the layered structures. The crystals jennite and tobermorite 9 demonstrate stronger mechanical behavior in the ab plane than the interlayer direction due to the presence of stable covalent "dreierketten" silicate chains. For tobermorite 11 Å, the Q3 silicate tetrahedrons bridging the neighboring calcium silicate sheets heal the weak interlayer structure and enhance the c-direction stiffness and cohesive strength. Furthermore, analysis of uniaxial tension by reactive force MD elucidated the chemical and mechanical responses of the atomic structures in loading resistance. The stress-strain relation of the layered mineral tensioned along b direction, showing the "strain hardening" region, where stress continues to increase past the yield stage. The strain hardening and ductility enhancement for the minerals is largely due to the ability of the silicate chains to first de-polymerize into short chains or separate tetrahedrons before the broken Q species re-polymerize to form branched networks and ring structures which are able to resist loading. For all three minerals, protons transfer to oxygen and water, resulting in the formation of Si-OH and Ca-OH groups during the strain hardening stage as Si-O-Si or Si-O-Ca bonds start to break and the calcium atoms and silicate morphology is rearranged. Hydrolysis therefore accelerates structural damage and contributes to weakening of mechanical properties in the interlayer direction. Increased tensile stress level in the tobermorite 11 Å can contribute to a greater extent of water damage.
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10
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Zhou Y, Hou D, Geng G, Feng P, Yu J, Jiang J. Insights into the interfacial strengthening mechanisms of calcium-silicate-hydrate/polymer nanocomposites. Phys Chem Chem Phys 2018. [PMID: 29528060 DOI: 10.1039/c8cp00328a] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The mechanical properties of organic/inorganic composites can be highly dependent on the interfacial interactions. In this work, with organic polymers intercalated into the interlayer of inorganic calcium silicate hydrate (C-S-H), the primary binding phase of Portland cement, great ductility improvement is obtained for the nanocomposites. Employing reactive molecular dynamics, the simulation results indicate that strong interfacial interactions between the polymers and the substrate contribute greatly to strengthening the materials, when C-S-H/poly ethylene glycol (PEG), C-S-H/poly acrylic acid (PAA), and C-S-H/poly vinyl alcohol (PVA) were subject to uniaxial tension along different lattice directions. In the x and z direction tensile processes, the Si-OCa bonds of the C-S-H gel, which were elongated and broken to form Si-OH and Ca-OH, play a critical role in loading resistance, while the incorporation of polymers bridged the neighboring silicate sheets, and activated more the hydrolytic reactions at the interfaces to avoid strain localization, thus increasing the tensile strength and postponing the fracture. On the other hand, Si-O-Si bonds of C-S-H mainly take the load when tension was applied along the y direction. During the post-yield stage, rearrangements of silicate tetrahedra occurred to prevent rapid damage. The polymer intercalation further elongates this post-yield period by forming interfacial Si-O-C bonds, which promote rearrangements and improve the connectivity of the defective silicate morphology, significantly improving the ductility. Among the polymers, PEG exhibits the strongest interaction with C-S-H, and thus C-S-H/PEG possesses the highest ductility. We expect that the molecular-scale mechanisms interpreted here will shed new light on the stress-activated chemical interactions at the organic/inorganic interfaces, and help eliminate the brittleness of cement-based materials on a genetic level.
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Affiliation(s)
- Yang Zhou
- Jiangsu Key Laboratory of Construction Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189, China and Department of Civil and Environmental Engineering, University of California, Berkeley, California 94720, USA and State Key Laboratory of High Performance Civil Engineering Materials, Jiangsu Research Institute of Building Science Co., Nanjing 211103, China
| | - Dongshuai Hou
- Department of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China.
| | - Guoqing Geng
- Department of Civil and Environmental Engineering, University of California, Berkeley, California 94720, USA and Laboratory for Waste Management, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Pan Feng
- Jiangsu Key Laboratory of Construction Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
| | - Jiao Yu
- Department of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China.
| | - Jinyang Jiang
- Jiangsu Key Laboratory of Construction Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
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11
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Zhou Y, Hou D, Manzano H, Orozco CA, Geng G, Monteiro PJM, Liu J. Interfacial Connection Mechanisms in Calcium-Silicate-Hydrates/Polymer Nanocomposites: A Molecular Dynamics Study. ACS APPLIED MATERIALS & INTERFACES 2017; 9:41014-41025. [PMID: 29076343 DOI: 10.1021/acsami.7b12795] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Properties of organic/inorganic composites can be highly dependent on the interfacial connections. In this work, molecular dynamics, using pair-potential-based force fields, was employed to investigate the structure, dynamics, and stability of interfacial connections between calcium-silicate-hydrates (C-S-H) and organic functional groups of three different polymer species. The calculation results suggest that the affinity between C-S-H and polymers is influenced by the polarity of the functional groups and the diffusivity and aggregation tendency of the polymers. In the interfaces, the calcium counterions from C-S-H act as the coordination atoms in bridging the double-bonded oxygen atoms in the carboxyl groups (-COOH), and the Ca-O connection plays a dominant role in binding poly(acrylic acid) (PAA) due to the high bond strength defined by time-correlated function. The defective calcium-silicate chains provide significant numbers of nonbridging oxygen sites to accept H-bonds from -COOH groups. As compared with PAA, the interfacial interactions are much weaker between C-S-H and poly(vinyl alcohol) (PVA) or poly(ethylene glycol) (PEG). Predominate percentage of the -OH groups in the PVA form H-bonds with inter- and intramolecule, which results in the polymer intertwining and reduces the probability of H-bond connections between PVA and C-S-H. On the other hand, the inert functional groups (C-O-C) in poly(ethylene glycol) (PEG) make this polymer exhibit unfolded configurations and move freely with little restrictions. The interaction mechanisms interpreted in this organic-inorganic interface can give fundamental insights into the polymer modification of C-S-H and further implications to improving cement-based materials from the genetic level.
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Affiliation(s)
- Yang Zhou
- School of Materials Science and Engineering, Southeast University , Nanjing 211189, China
- Department of Civil and Environmental Engineering, University of California , Berkeley, California 94720, United States
- State Key Laboratory of High Performance Civil Engineering Materials, Jiangsu Research Institute of Building Science Co. , Nanjing 211103, China
| | - Dongshuai Hou
- School of Civil Engineering, Qingdao Technological University , Qingdao 266033, China
| | - Hegoi Manzano
- Department of Condensed Matter Physics, University of the Basque Country UPV/EHU , Barrio Sarriena s/n, 48960 Leioa, Spain
| | - Carlos A Orozco
- Department of Civil and Environmental Engineering, University of California , Berkeley, California 94720, United States
| | - Guoqing Geng
- Department of Civil and Environmental Engineering, University of California , Berkeley, California 94720, United States
| | - Paulo J M Monteiro
- Department of Civil and Environmental Engineering, University of California , Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Jiaping Liu
- School of Materials Science and Engineering, Southeast University , Nanjing 211189, China
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Geng G, Myers RJ, Qomi MJA, Monteiro PJM. Densification of the interlayer spacing governs the nanomechanical properties of calcium-silicate-hydrate. Sci Rep 2017; 7:10986. [PMID: 28887517 PMCID: PMC5591233 DOI: 10.1038/s41598-017-11146-8] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 08/18/2017] [Indexed: 11/20/2022] Open
Abstract
Calciuam-silicate-hydrate (C-S-H) is the principal binding phase in modern concrete. Molecular simulations imply that its nanoscale stiffness is ‘defect-driven’, i.e., dominated by crystallographic defects such as bridging site vacancies in its silicate chains. However, experimental validation of this result is difficult due to the hierarchically porous nature of C-S-H down to nanometers. Here, we integrate high pressure X-ray diffraction and atomistic simulations to correlate the anisotropic deformation of nanocrystalline C-S-H to its atomic-scale structure, which is changed by varying the Ca-to-Si molar ratio. Contrary to the ‘defect-driven’ hypothesis, we clearly observe stiffening of C-S-H with increasing Ca/Si in the range 0.8 ≤ Ca/Si ≤ 1.3, despite increasing numbers of vacancies in its silicate chains. The deformation of these chains along the b-axis occurs mainly through tilting of the Si-O-Si dihedral angle rather than shortening of the Si-O bond, and consequently there is no correlation between the incompressibilities of the a- and b-axes and the Ca/Si. On the contrary, the intrinsic stiffness of C-S-H solid is inversely correlated with the thickness of its interlayer space. This work provides direct experimental evidence to conduct more realistic modelling of C-S-H-based cementitious material.
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Affiliation(s)
- Guoqing Geng
- Department of Civil and Environmental Engineering, University of California, Berkeley, California, 94720, United States.
| | - Rupert J Myers
- Department of Civil and Environmental Engineering, University of California, Berkeley, California, 94720, United States.,School of Forestry & Environmental Studies, Yale University, New Haven, Connecticut, 06511, United States
| | | | - Paulo J M Monteiro
- Department of Civil and Environmental Engineering, University of California, Berkeley, California, 94720, United States. .,Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, United States.
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Ortaboy S, Li J, Geng G, Myers RJ, Monteiro PJM, Maboudian R, Carraro C. Effects of CO2 and temperature on the structure and chemistry of C–(A–)S–H investigated by Raman spectroscopy. RSC Adv 2017. [DOI: 10.1039/c7ra07266j] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Calcium (alumino)silicate hydrate (C–(A–)S–H) is the critical binding phase in modern Portland cement-based concrete, yet the relationship between its structure and stoichiometry is not completely understood.
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Affiliation(s)
- Sinem Ortaboy
- Department of Chemical and Biomolecular Engineering
- University of California
- Berkeley
- USA
- Chemistry Department
| | - Jiaqi Li
- Department of Civil and Environmental Engineering
- University of California
- Berkeley
- USA
| | - Guoqing Geng
- Department of Civil and Environmental Engineering
- University of California
- Berkeley
- USA
| | - Rupert J. Myers
- Department of Civil and Environmental Engineering
- University of California
- Berkeley
- USA
- School of Engineering
| | - Paulo J. M. Monteiro
- Department of Civil and Environmental Engineering
- University of California
- Berkeley
- USA
| | - Roya Maboudian
- Department of Chemical and Biomolecular Engineering
- University of California
- Berkeley
- USA
| | - Carlo Carraro
- Department of Chemical and Biomolecular Engineering
- University of California
- Berkeley
- USA
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