Temperature Effects on Tensile and Compressive Mechanical Behaviors of C-S-H Structure via Atomic Simulation

Xin, Hao; Lin, Wenjun; Fu, Jia; Li, Wu; Wang, Zhihua

doi:10.1155/2017/8476258

Cited by 26 publications

(7 citation statements)

References 14 publications

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“…In peculiar, the C-S-H gel showed heavy bi-modulus behavior [ 67 ]. The differences among the moduli in different directions were well aligned with the previous uniaxial MD simulation results [ 32 , 39 , 68 ]. The bi-modulus behavior when tested in the z-direction was mainly caused by the layout of the C-S-H layers.…”

Section: Resultssupporting

confidence: 89%

Nanoindentation Study of Calcium-Silicate-Hydrate Gel via Molecular Dynamics Simulations

Yin,

Wang,

Qin

et al. 2023

Nanomaterials

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The mechanical properties of calcium-silicate-hydrate (C-S-H) gels in cementitious materials are mainly realized by nanoindentation experiments. There is limited research on the dynamic response of the molecular structure of C-S-H under nanoindentation conditions. This study simulated the nanoindentation on the C-S-H gel samples by the molecular dynamics method considering the essential factors of modeling and loading process. The results demonstrate that the averaged elastic moduli we obtained had slight differences from those by experiments. In contrast to the experimental results, the gels showed bi-modulus and transverse isotropic with the material principal direction perpendicular to the C-S-H layers. The modulus in a direction increased with the loading speed, which indicates that C-S-H behaves viscous due to the water motion in the sample and the propagation of stress wave. The saturation of water influenced the moduli differently because more water in C-S-H will reduce the polymerization of silicon chains and then weaken the local stiffness. The conclusions provide a deeper understanding of the mechanism on the unique mechanical response of C-S-H gels.

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Section: Resultssupporting

confidence: 89%

Nanoindentation Study of Calcium-Silicate-Hydrate Gel via Molecular Dynamics Simulations

Yin,

Wang,

Qin

et al. 2023

Nanomaterials

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“…The RDF of an amorphous system has a wave peak only in the proximity, and tends toward 1 as the radius increases [30]. Given that the ClayFF force field employed different potential energy parameters for the interlayer calcium (Ca h ) and intralayer calcium (Ca o ) in the C-S-H [31], the Ca h dominated the motion of Ca 2+ ions within the model. Therefore, the RDF was analyzed in this paper by counting the Ca h .…”

Section: Analysis Of Interaction Mechanismsmentioning

confidence: 99%

“…Sci. 2023, 13, x FOR PEER REVIEW 7 of 12 energy parameters for the interlayer calcium (Cah) and intralayer calcium (Cao) in the C-S-H [31], the Cah dominated the motion of Ca 2+ ions within the model. Therefore, the RDF was analyzed in this paper by the Cah.…”

Section: Analysis Of Interaction Mechanismsmentioning

confidence: 99%

Influence Mechanism of the Interfacial Water Content on Adhesive Behavior in Calcium Silicate Hydrate−Silicon Dioxide Systems: Molecular Dynamics Simulations

Huang

Yang

2023

Applied Sciences

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The performance indicators of concrete are mainly determined by the interface characteristics between cement hydration slurry and aggregates. In this study, molecular dynamics technology was used to evaluate the effect of the interfacial water content on the evolution of the interface structure, interaction energy, and mechanical properties of calcium silicate hydrate (C-S-H) and silicon dioxide (SiO2) systems, and the weakening mechanism of the C-S-H/SiO2 interface in a humid environment was revealed. The results showed that all stress–strain curves of C-S-H/SiO2 were divided into the elastic stage and the failure stage. As the interfacial water layer thickened, the molecular weight of the water invading the C-S-H gradually increased, and the desorption of Ca2+ ions in the surface region became significant, while the amount of Ca2+ ions entering the water-layer region increased. The interaction energy of the C-S-H/SiO2 progressively became larger, and the energy ratio (ER) significantly decreased; the tensile strength σc and residual strength σr of C-S-H/SiO2 both showed a downward trend. In summary, a lower water content had a limited impact on the interfacial bonding strength, while the weakening effect enhanced with an increase in the interfacial water content. This phenomenon was also demonstrated in concrete interfacial bond strength experiments.

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“…Hou et al (2014a) investigated the mechanical and structural character of C-S-H with different interlayer water content, and they found that lower water content can result in a higher strength and modulus. In addition, the decomposition of the hydroxyl group and water evaporation induced by high temperature can considerably influence the mechanical property of the C-S-H grain (Zhang et al, 2020a(Zhang et al, , 2021a(Zhang et al, , 2021b, and the interlayer water has a primary effect on the cohesive force between solid C-S-H grains and the mechanical property of the C-S-H grain-both at ambient (Hou et al, 2014a(Hou et al, , 2014bManzano et al, 2009;Rivas Murillo et al, 2017;Xin et al, 2017;Zhou and Liang, 2019) and high temperature levels (Bonnaud et al, 2013;DeJong and Ulm, 2007;Li et al, 2017). Furthermore, Yang et al (2021) investigated the effect of the dehydration and dihydroxylation on the evolution of mechanical properties of C-S-H.…”

Section: Introductionmentioning

confidence: 99%

Insights into the effect of high temperature on the shear behavior of the calcium silicate hydrate by reactive molecular dynamics simulations

Zhang

Chen

et al. 2022

International Journal of Damage Mechanics

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When subjected to fires, cementitious composites can be seriously damaged. However, the mechanical behavior of nanoscale calcium silicate hydrate (C–S–H) grains, which are the main binder of cementitious composites, exposed to elevated temperatures under shear deformations remain poorly investigated. In this paper, considering different calcium/silicate (C/S) molar ratios (i.e., C/S = 1.10, 1.33, and 1.64), the shear behavior of the C–S–H grain after exposure to different high-temperature levels (i.e., 300 K, 500 K, 700 K, 900 K, and 1000 K) is studied by conducting series of reactive molecular dynamics simulations. Results reveal that the C–S–H grain exhibits good plasticity under shear deformation. Furthermore, the shear modulus of the C–S–H grain is between 14 GPa and 17 GPa and exhibits a decrease with the calcium/silicon (C/S) molar ratio at ambient temperature. While the shear strength is around 1.0 GPa and reaches the lowest value at C/S = 1.64. Interestingly, we report that heating can lead to the increase of the shear modulus and shear strength due to the sevaporation of the interlayer water which generally acts as the lubricant. Additionally, we show that heating has no clear influence on the shear strain corresponding to the onset of yielding when the C/S ratio is high but can indeed improve the shear strain corresponding to the shear strength. Furthermore, the yielding area of the C–S–H grain under the shear deformation can be enlarged. Finally, factors affecting the strength degradation of cementitious composites after being heated to different temperature levels are further discussed based on the simulation results.

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Temperature Effects on Tensile and Compressive Mechanical Behaviors of C-S-H Structure via Atomic Simulation

Cited by 26 publications

References 14 publications

Nanoindentation Study of Calcium-Silicate-Hydrate Gel via Molecular Dynamics Simulations

Nanoindentation Study of Calcium-Silicate-Hydrate Gel via Molecular Dynamics Simulations

Influence Mechanism of the Interfacial Water Content on Adhesive Behavior in Calcium Silicate Hydrate−Silicon Dioxide Systems: Molecular Dynamics Simulations

Insights into the effect of high temperature on the shear behavior of the calcium silicate hydrate by reactive molecular dynamics simulations

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