Fracture toughness of calcium–silicate–hydrate from molecular dynamics simulations

Bauchy, Mathieu; Laubie, Hadrien; Qomi, Mohammad Javad Abdolhosseini; Hoover, Christian G.; Ulm, Franz Josef; Pellenq, Roland

doi:10.1016/j.jnoncrysol.2015.03.031

Cited by 172 publications

(131 citation statements)

References 56 publications

Supporting

Mentioning

112

Contrasting

Order By: Relevance

“…It follows from theoretical works (e.g. Ghebrab and Soroushian [11]) that CH crystal pull-out raises the values of pure C-S-H to much higher values, 16.9-283 J/m 2 , which is in relation to our findings, whereas the pure C-S-H fracture energy ranges only between 0.38-2.85 J/m 2 [11,12].…”

Section: Fracture Energy and Fracture Toughnesssupporting

confidence: 91%

Combined investigation of Low-scale Fracture in Hydrated Cement and metal alloys Assessed by Nanoindentation and FIB

Němeček¹,

Hrbek²,

Polívka³

et al. 2016

Proceedings of the 9th International Conference on Fracture Mechanics of Concrete and Concrete Structures

View full text Add to dashboard Cite

This paper deals with an assessment of fracture properties of micro-level components of hydrated cement paste. Fracture energy and fracture toughness are studied by means of several experimental techniques at the micrometer scale. Nanoindentation is used as a primary tool for the material characterization. The work includes analysis of fracture mechanisms under the sharp indenter using focused ion beam (FIB) technology combined with scanning electron microscopy (SEM). Usual microscale approaches used in brittle solids are based on the observation of cracks from surface view after indentation. In this work, an energetic approach and decomposition of work of indentation into plastic and other parts is used instead. Based on cross sectioning of indents via FIB, several assumptions are done on the fracture area under the tip and semi-quantitative estimates of the low-scale fracture energy are performed for the cement paste components. Statistical deconvolution is applied to sort out the individual phase fracture properties.

show abstract

Section: Fracture Energy and Fracture Toughnesssupporting

confidence: 91%

Combined investigation of Low-scale Fracture in Hydrated Cement and metal alloys Assessed by Nanoindentation and FIB

Němeček¹,

Hrbek²,

Polívka³

et al. 2016

Proceedings of the 9th International Conference on Fracture Mechanics of Concrete and Concrete Structures

View full text Add to dashboard Cite

show abstract

“…Therefore, the homogenized thermal conductivity of cement paste can be implicitly expressed in terms of hydration degree and the thermal-conductivity values of individual phases (Table II) through Eq. (22). Figure 8(b) presents the thermal conductivity as a function of hydration degree for resulting cement pastes produced from the hydration of pure C 2 S and C 3 S clinkers at different w=c ratios (w=c ¼ 0.3 and 0.5) for saturated meso-and micropores compared with experimental measurements of Bentz [7] for cement of varying w=c ratio and curing conditions.…”

Section: Macroscale Thermal Propertiesmentioning

confidence: 99%

“…We have previously studied mechanical properties [18][19][20][21][22][23] and diffusion dynamics [24] of cement paste at the molecular level. In this paper, we focus on understanding the physical origins of macroscopic thermal properties of cement paste, starting from the atomic scale.…”

Section: Introductionmentioning

confidence: 99%

Physical Origins of Thermal Properties of Cement Paste

2015

View full text Add to dashboard Cite

Despite the ever-increasing interest in multiscale porous materials, the chemophysical origin of their thermal properties at the nanoscale and its connection to the macroscale properties still remain rather obscure. In this paper, we link the atomic-and macroscopic-level thermal properties by combining tools of statistical physics and mean-field homogenization theory. We begin with analyzing the vibrational density of states of several calcium-silicate materials in the cement paste. Unlike crystalline phases, we indicate that calcium silicate hydrates (CSH) exhibit extra vibrational states at low frequencies (< 2 THz) compared to the vibrational states predicted by the Debye model. This anomaly is commonly referred to as the boson peak in glass physics. In addition, the specific-heat capacity of CSH in both dry and saturated states scales linearly with the calcium-to-silicon ratio. We show that the nanoscale-confining environment of CSH decreases the apparent heat capacity of water by a factor of 4. Furthermore, full thermal conductivity tensors for all phases are calculated via the Green-Kubo formalism. We estimate the mean free path of phonons in calcium silicates to be on the order of interatomic bonds. This satisfies the scale separability condition and justifies the use of mean-field homogenization theories for upscaling purposes. Upscaling schemes yield a good estimate of the macroscopic specific-heat capacity and thermal conductivity of cement paste during the hydration process, independent of fitting parameters.

show abstract

“…For instance, increasing cement's porosity lowers its thermal conductivity, while this significantly decreases its mechanical properties. In a community driven by interest in superior strength and stiffness, [2][3][4][5] it is imperative to seek solutions that reduce the thermal conductivity of the construction material without decreasing its mechanical properties. In the glass community, researchers [6][7][8][9][10][11][12][13] have shown that both phonon-like propagating modes (propagons) and diffusive modes (diffusons) contribute significantly to the thermal conductivity.…”

mentioning

confidence: 99%

The contribution of propagons and diffusons in heat transport through calcium-silicate-hydrates

Zhou

Morshedifard

Lee

et al. 2017

Applied Physics Letters

View full text Add to dashboard Cite

Whether it is glass, ceramics, cement, or concrete, minimizing thermal conduction through disordered materials is a determining factor when it comes to reducing the energy consumption of cities. In this work, we explore underlying physical processes involved in thermal conduction through the disordered glue of cement, calcium-silicate-hydrates (CSH). We find that at 300 K, phonon-like propagating modes in accordance with the Boltzmann transport theory, propagons, account for more than 30% of the total thermal conductivity, while diffusons, described via the Allen-Feldman theory, contribute to the remainder. The cumulative thermal conductivity proves to be close to both equilibrium molecular dynamics calculations and experimental values. These findings help us establish different strategies, such as localization schemes (to weaken diffusons) and scattering mechanisms (to constrain propagons), for reduction of thermal conductivity of CSH without sacrificing its mechanical properties.

show abstract

Fracture toughness of calcium–silicate–hydrate from molecular dynamics simulations

Cited by 172 publications

References 56 publications

Combined investigation of Low-scale Fracture in Hydrated Cement and metal alloys Assessed by Nanoindentation and FIB

Combined investigation of Low-scale Fracture in Hydrated Cement and metal alloys Assessed by Nanoindentation and FIB

Physical Origins of Thermal Properties of Cement Paste

The contribution of propagons and diffusons in heat transport through calcium-silicate-hydrates

Contact Info

Product

Resources

About