Mechanical properties of calcium silicate hydrate under uniaxial and biaxial strain conditions: A molecular dynamics study

2021 ◽  
Author(s):  
Yongming Tu ◽  
Pan Shi ◽  
Dongyun Liu ◽  
Rongjia Wen ◽  
Qian Yu ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Hydration Product ◽  
Cementitious Materials ◽  
Complex Stress ◽  
Biaxial Strain ◽  
Practical Applications ◽  
Reactive Molecular Dynamics ◽  
Molecular Dynamics Methods

Calcium silicate hydrate (C-S-H) is the main hydration product of cementitious materials, often experiencing complex stress conditions in practical applications. Therefore, reactive molecular dynamics methods were used to investigate the...

Xonotlite and Hillebrandite as Model Compounds for Calcium Silicate Hydrate Seeding in Cementitious Materials

2020 ◽  
pp. 036119812094320
Author(s):  
Elisabeth John ◽  
Christian Lehmann ◽  
Dietmar Stephan
Keyword(s):  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Model Compound ◽  
Hydration Product ◽  
Cementitious Materials ◽  
Nucleation Site ◽  
Hydration Products ◽  
Sem Images ◽  
Pit Formation ◽  
Nanoparticle Additives

The demand for more environmentally friendly cement with no disadvantages in relation to hydration activity has led to the development of various additives to accelerate cement hydration. As calcium silicate hydrate (C-S-H) is the major hydration product of cement and is responsible for its mechanical properties, it plays an outstanding role in the discussion of nanoparticle additives. Nevertheless, the investigation of its mechanism of action is complicated by the similarity of its properties to those of the C-S-H that forms as an initial hydration product. Crystalline C-S-H phases, on the other hand, can be easily distinguished from the original hydration products, which makes them a valuable model compound for studying the mechanisms of nucleation seeding in cementitious materials. In this paper, the effect of crystalline types of C-S-H as nucleation seeds are presented. Xonotlite and hillebrandite were thoroughly characterized using nuclear magnetic resonance, X-ray diffractometry (XRD), scanning electron microscopy (SEM), and infrared spectroscopy (IR) and were then used as an admixture for alite pastes. Low-vacuum SEM images of the hydrated pastes revealed that xonotlite can significantly promote the visible etch pit formation on C3S clinker particles, which was not found to be true for hillebrandite. Whether the phases act as a nucleation site is assumed to be strongly dependent on the mineralogy: hillebrandite appeared to be heavily overgrown, but xonotlite did not show any hydration products on its surfaces after the same hydration time of up to 24 h. The diverse effect of the minerals was confirmed by the accelerating behavior in isothermal heat flow calorimetry and by XRD.

scholarly journals Effect of Water on the Dynamic Tensile Mechanical Properties of Calcium Silicate Hydrate: Based on Molecular Dynamics Simulation

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2837 ◽  
Author(s):  
Jikai Zhou ◽  
Yuanzhi Liang
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Water Content ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Cementitious Materials ◽  
Constitutive Relationship ◽  
Degree Of Saturation ◽  
Strain Rates ◽  
Effect Of Water

To study the effect of water on the dynamic mechanical properties of calcium silicate hydrate (C–S–H) at the atomic scale, the molecular dynamics simulations were performed in uniaxial tension with different strain rates for C–S–H with a degree of saturation from 0% to 100%. Our calculations demonstrate that the dynamic tensile mechanical properties of C–S–H decrease with increasing water content and increase with increasing strain rates. With an increase in the degree of saturation, the strain rate sensitivity of C–S–H tends to increase. According to Morse potential function, the tensile stress-strain relationship curves of C–S–H are decomposed and fitted, and the dynamic tensile constitutive relationship of C–S–H considering the effect of water content is proposed. This reveals the strain rate effect of the cementitious materials with different water content from molecular insights, and the dynamic constitutive relationship obtained in this paper is necessary to the modelling of cementitious materials at the meso-scale.

Molecular Dynamics Study of the Interaction of C-S-H and Chloride Ions

2016 ◽  
Vol 711 ◽  
pp. 1061-1068
Author(s):  
Yang Zhou ◽  
Guo Dong Xu
Keyword(s):  
Molecular Dynamics ◽  
Calcium Silicate Hydrate ◽  
Chloride Concentration ◽  
Sorption Isotherms ◽  
Hydration Product ◽  
Chloride Ions ◽  
Dynamics Modeling ◽  
Solution Interface ◽  
Molecular Dynamics Modeling ◽  
Cement Based Materials

Molecular Dynamics was employed to investigate the interaction of calcium silicate hydrate (C-S-H), the primary hydration product of cement based materials, and chloride, causing severe durable problems of concrete. The 11Å tobermorite structure was chosen to describe the C-S-H structure and the CLAYFF force field was used. It is observed in the simulation that there are no bound chlorides at 303K, while a fraction of chlorides appear in the adsorption district of tobermorite/solution interface at 323K indicating the temperature increase can improve chloride sorption capacity of C-S-H. The formation of Ca-Cl cluster is found on the surface of tobermorite, which is assumed to promote the chloride sorption. The experimental results of sorption isotherms of C-S-H in CaCl2 and NaCl aqueous solutions with the same chloride concentration have proved this point. Other researchers have made the same conclusion by means of molecular dynamics modeling, NMR tests or zeta potential experiments.

Heterogeneous Nature of Calcium Silicate Hydrate (C-S-H) Gel: A Molecular Dynamics Study

2020 ◽  
Vol 35 (2) ◽  
pp. 435-440
Author(s):  
Shucheng Jin ◽  
Jinhui Li ◽  
Wenyuan Xu ◽  
Qingjun Ding
Keyword(s):  
Molecular Dynamics ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Heterogeneous Nature

Molecular dynamics study on calcium silicate hydrate subjected to tension loading and water attack: structural evolution, dynamics degradation and reactivity mechanism

2018 ◽  
Vol 20 (16) ◽  
pp. 11130-11144 ◽  
Author(s):  
Dongshuai Hou ◽  
Jiao Yu ◽  
Zuquan Jin ◽  
Asad Hanif
Keyword(s):  
Molecular Dynamics ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Structural Evolution ◽  
Hydrolytic Reaction ◽  
Evolution Dynamics ◽  
Tension Loading

The water invasion and hydrolytic reaction further weakens the tensioned C–S–H structure.

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