Bottom‐Up: From Atoms to Concrete Structures

15The atomic structure of calcium-silicate-hydrate (C1,67-S-Hx) has been investigated by 16 theoretical methods in order to establish a better insight into its structure. Three models for C-17 S-H all derived from tobermorite are proposed and a large number of structures were created 18 within each model by making a random distribution of silica oligomers of different size 19 within each structure. These structures were subjected to structural relaxation by geometry 20 optimization and molecular dynamics steps. That resulted in a set of energies within each 21 model. Despite an energy distribution between individual structures within each model, 22 significant energy differences are observed between the three models. The C-S-H model 1 related to the lowest energy is considered as the most probable. It turns out to be characterized 2 by the distribution of dimeric and pentameric silicate and the absence of monomers. This 3 model has mass density which is the closest to the experimental one. 4 5

show abstract

“…The determination of the exact C-S-H structure remains an important issue because of its importance in other meso-and macroscopic models [54,55]…”

Section: Introductionmentioning

confidence: 99%

Atomistic modeling of crystal structure of Ca 1.67 SiH x

Kovačević

Persson

Nicoleau³

et al. 2015

Cement and Concrete Research

View full text Add to dashboard Cite

show abstract

“…Cement paste binds the coarse/fine aggregates and any other fiber reinforcement to form a structural unit, after hydration (Chandler et al, 2010(Chandler et al, , 2012(Chandler et al, , 2013Garboczi and Bentz, 1996;Jennings et al, 2005;Mehta and Monteiro, 2006;Powers and Brownyard, 1948;Richardson, 2002;Taylor, 1997;Ulm et al, 2010). Cement paste has been found to play a central role in the development of the mechanical properties of the cementitious materials (Powers and Brownyard, 1948).…”

Section: Introductionmentioning

confidence: 99%

“…The characteristics and properties of the CSH gel are thought to be key dominant factors in the behavior of the cement paste under loading (Bernard et al, 2003;Garboczi and Bentz, 1996;Taylor, 1997). Researchers believe CSH gel is responsible for the strength and the deformation behavior of the material at all the different length scales (Jennings et al, 2005;Ulm et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Computational modeling of shear deformation and failure of nanoscale hydrated calcium silicate hydrate in cement paste: Calcium silicate hydrate Jennite

Murillo

Mohamed

Hodo³

et al. 2015

International Journal of Damage Mechanics

View full text Add to dashboard Cite

Calcium silicate hydrate Jennite is a molecular structure commonly accepted as a representation of the complex calcium silicate hydrate gel formed during the hydration of typical Portland cement. In this paper, the behavior of nanoscale calcium silicate hydrate Jennite under shear deformation was investigated using molecular dynamics simulations. Computational samples representing the nanoscale structure of calcium silicate hydrate Jennite were subjected to shear deformation in order to investigate not only their mechanical properties but also their deformation behavior. The simulation results indicated that the nanoscale calcium silicate hydrate Jennite under shear deformation displays a linear elastic behavior up to shear stress of approximately 1.0 GPa, and shear deformation of about 0.08 radians, after which point yielding and plastic deformation occurs. The shear modulus determined from the simulations was 11.2 ± 0.7 GPa. The deformation-induced displacements in molecular structures were analyzed dividing the system in regions representing calcium oxide layers. The displacement/deformation of the layers of calcium oxide forming the structure of nanoscale calcium silicate hydrate Jennite was analyzed. The non-linear stress–strain behavior in the molecular structure was attributed to a non-linear increase in the displacement due to sliding of the calcium oxide layers on top of each other with higher shearing. These results support the idea that by controlling the chemical reactions, the tailored morphologies can be used to increase the interlinking between the calcium oxide layers, thus minimizing the shearing of the layers and leading to molecular structures that can withstand larger deformation and have improved failure behavior.

show abstract

“…Dabei werden insbesondere auch "Bottom-up"-Verfahren angestrebt. Ziel ist es, die Eigenschaften von Beton aus seinen Grundbestandteilen (Atome) in makroskopischen Strukturen "aufzubauen", [107] zum Beispiel um plastische Verformungen zu minimieren. [108] Es bedarf jedoch noch erheblichen Aufwands, um die richtigen Moleküle oder Additive für die Bildung einer Zementstruktur im Nanobereich mit den gewünschten verbesserten Eigenschaften zu entwerfen.…”

Section: Industrielle Bedeutung -Nutzung Der Vorläuferstrukturenunclassified

Die Bildung von Nanopartikeln und Nanostrukturen – CaCO₃, Zement und Polymere aus Sicht der Industrie

Rieger

Kellermeier

Nicoleau³

2014

Angewandte Chemie

View full text Add to dashboard Cite

Nanotechnologie ermöglicht die Herstellung von Materialien mit hervorragenden Leistungscharakteristika. Ein Schlüsselelement der Nanotechnologie ist die Fähigkeit, Materie auf der Nanoskala zu manipulieren und zu steuern, um einen gewünschten Mix aus spezifischen Eigenschaften zu erhalten. Hier stellen wir jüngste Erkenntnisse zu den Bildungsmechanismen von anorganischen Nanopartikeln im Rahmen von Fällungsreaktionen vor. Am Beispiel von Calciumcarbonat beschreiben wir die verschiedenen Zwischenstufen, die auf dem Weg von den gelösten Ionen bis zu stabilen Makrokristallen auftreten können – einschließlich gelöster Ionencluster, flüssiger Phasen, amorpher Zustände und Nanopartikeln. Die Rolle von Polymeren bei der Nukleation, Templatierung, Stabilisierung und/oder Verhinderung dieser Strukturen wird skizziert. Als Beispiel für angewandte Nanotechnologie diskutieren wir die Eigenschaften von Zement, die durch die Bildung und das Ineinandergreifen von Calcium‐Silikat‐Hydrat‐Nanoplättchen festgelegt werden. Die Aggregation dieser Plättchen hin zu mesoskaligen Gebilden kann mithilfe von Polymeren gesteuert werden.

show abstract

Bottom‐Up: From Atoms to Concrete Structures

Cited by 3 publications

References 16 publications

Atomistic modeling of crystal structure of Ca 1.67 SiH x

Atomistic modeling of crystal structure of Ca 1.67 SiH x

Computational modeling of shear deformation and failure of nanoscale hydrated calcium silicate hydrate in cement paste: Calcium silicate hydrate Jennite

Die Bildung von Nanopartikeln und Nanostrukturen – CaCO₃, Zement und Polymere aus Sicht der Industrie

Contact Info

Product

Resources

About

Bottom‐Up: From Atoms to Concrete Structures

Cited by 3 publications

References 16 publications

Atomistic modeling of crystal structure of Ca 1.67 SiH x

Atomistic modeling of crystal structure of Ca 1.67 SiH x

Computational modeling of shear deformation and failure of nanoscale hydrated calcium silicate hydrate in cement paste: Calcium silicate hydrate Jennite

Die Bildung von Nanopartikeln und Nanostrukturen – CaCO3, Zement und Polymere aus Sicht der Industrie

Contact Info

Product

Resources

About

Die Bildung von Nanopartikeln und Nanostrukturen – CaCO₃, Zement und Polymere aus Sicht der Industrie