Molecular dynamics simulation to assess the effect of temperature on diffusion coefficients of different ions and water molecules in C-S-H

Zehtab, Behnam; Tarighat, Amir

doi:10.1007/s11043-017-9368-6

Cited by 22 publications

(5 citation statements)

References 57 publications

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“…The models need a limited number of input parameters: elastic properties of cement phases for the mechanical model and diffusion coefficients of cement phases for the transport model. While in this research these have been based on literature data, in principle lower scale models [such as molecular dynamics (Pellenq et al 2009;Zehtab and Tarighat 2018)] can be used to determine the input parameters. First, the validity of the models has been shown by comparing the results with data available from the literature.…”

Section: Discussionmentioning

confidence: 99%

Assessing Hydrated Cement Paste Properties Using Experimentally Informed Discrete Models

Šavija

Zhang

Schlangen

2019

J. Mater. Civ. Eng.

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Properties of concrete are, to a large extent, dependent on the properties of its binding constituent, hydrated cement paste. Therefore, knowledge of properties of hydrated cement paste is crucial for predicting concrete behavior. This paper presents an experimentally informed approach for modeling elastic and transport properties of cement paste. The models used realistic microstructural informationobtained by X-ray computed tomography-as input for property determination. The properties were then determined using discrete numerical models, namely, models based on a lattice approach. Modeling results were compared with literature data, showing excellent correlations. Furthermore, dependence of properties of cement paste on the total porosity, based on the modeling results, was explored. Finally, a correlation between elastic and transport properties for the explored range of portland cement pastes was established. It is seen that the models can be used for property prediction, but also for exploring correlations between different parameters.

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Section: Discussionmentioning

confidence: 99%

Assessing Hydrated Cement Paste Properties Using Experimentally Informed Discrete Models

Šavija

Zhang

Schlangen

2019

J. Mater. Civ. Eng.

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“…Thus, many phenomena related to the field of cementitious materials were found to be well described by the activation/rate theory. For instance, hydration (Bazant et al 2004), permeability (Powers 1979), moisture diffusion (Hughes et al 1966;Hancox 1968), diffusion of ions (Nakashima 1995;Otsuki et al 2009;Zehtab and Tarighat 2018), creep (Klug and Wittmann 1969;Day and Gamble 1983;Bazant 1988), and even aging of cracked concrete (Pertué et al 2013) have already been analyzed through this approach. In this study, the activation energy related to the rate of exchange between large and fine pores during the water uptake process will be calculated.…”

Section: Activation Energy Of the Rate Of Exchange Between Large And ...mentioning

confidence: 99%

Cement and Concrete for Nuclear Waste Management

Nakarai¹,

Kosakowski²

2022

ACT

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The safe management and disposal of radioactive wastes are of critical importance for maintaining a sustainable society. In nuclear waste management, cement and concrete are commonly used to immobilize radioactive waste. Cementation is a common technique used for conditioning low-level and intermediate-level radioactive wastes, which should ensure safe interim storage of waste packages, and act as a first long-term barrier during waste disposal. In addition, cement-based materials are utilized for construction and barrier materials in surface disposals for very low-level to low-level waste and deep geological disposals for low-level, intermediate-level, and high-level wastes.Furthermore, recovery from the nuclear disaster at the Fukushima Daiichi Nuclear Power Station (F1NPS) is an important and urgent issue in Japan. To solve the difficult problems associated with radioactive contaminated materials in the plant and in the environment, contributions of cement and concrete technologies are highly expected.The understanding end prediction of the long-term evolution of cement materials interacting with wastes and other barrier materials during interim and final storage is indispensable and needs to be studied by experts from different scientific and engineering disciplines. The very long times associated with the safe disposal of radioactive waste, which are well beyond the lifetime of ordinal engineered structures and therefore not experimentally accessible, make this task even more demanding.In the first part of this special issue, three technical contributions summarize research and development projects for nuclear waste management with cement and concrete technologies in Japan. and Ichikawa and Hamamoto (19-1275) give general overviews on the use of cement-based materials for low-level radioactive waste (LLW) and for high-level radioactive waste (HLW), respectively. Furthermore, Abe and Iida (20-236) present a comparative discussion of approaches used for LLW in Japan and Belgium.In the second part, the contributions concentrate on processes and applications related to the performance assessment of cement and concrete for nuclear waste management. The scientific papers describe sorption experiments with Cl, I, HTO, and C by Nedyalkova et al. (19-811), diffusion experiments with NaCl of leached cement paste by Kurmisawa et al. (19-426), leaching experiments of cement paste with quick setting admixture by Yokozeki et al. (19-1173), immersion experiments of cement-bentonite samples by Nakarai et al. (19-433, 19-447), and chemo-mechanical modelling of degraded concrete by Oda et al. (19-1075).Finally, the third part contains contributions that investigate, in a broad sense, how cement and concrete technologies can be used to deal with the aftermath of the F1NPS nuclear disaster. At first, a technical paper by summarizes the outcome of a research initiative that aimed at identifying the cause and extent of radioactive contamination of concrete at the F1NPS.A set of scientific contributions is related to water abso...

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“…The coexistence of 14‐Å tobermorite–jennite was identified by high‐resolution transmission electron microscopy (HRTEM)/electron diffraction as nanocrystalline regions with structural elements of both CSH phases 54 . Significant sings of progress using simulation models of (11 and 14 Å) tobermorite and jennite C–S–H structures provide information about the effect of different factors 64–67 …”

Section: Introductionmentioning

confidence: 99%

“…54 Significant sings of progress using simulation models of (11 and 14 Å) tobermorite and jennite C-S-H structures provide information about the effect of different factors. [64][65][66][67] Unlike the extensive progress on these C-S-H phases, there is insufficient knowledge about afwillite, its growth F I G U R E 1 Crystal models calculated for (A) monoclinic afwillite, 44 (B) triclinic afwillite, 59 (C) tobermorite 11 Å, 61 (D) tobermorite 14 Å, 63 (E) jennite. 52 Source: Reference data taken from AMCSD.…”

Section: Introductionmentioning

confidence: 99%

Evolution of C–S–H in lime mortars with nanoparticles: Nanostructural analysis of afwillite growth mechanisms by HRTEM

et al. 2022

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This work studies the formation of calcium–silicate–hydrates (C–S–H) in lime mortars prepared with additions of nano‐Ca(OH)2 and nano‐SiO2 at 23.3°C. Mineral identification was carried out by X‐ray diffraction after 10, 30, 90, and 120 days of curing. The nanoscale study starts from the generation of amorphous phases until the development of crystalline phases. Observations of binder mortar made by transmission electron microscopy (low magnification and high resolution TEM) after 30 and 110 days of curing showed the formation of two types of C–S–H with different degrees of crystallinity depending on the curing time. The development of short‐range order C–S–H globular phases was visible after 30 days. C–S–H evolved into lamellar crystalline phases visible after 110 days of curing. The crystalline phase corresponds to the C–S–H known as afwillite (Ca3(SiO3OH)2·2H2O), first reported to affect cement and concrete's mechanical and hydration properties. It appears as isolated fibers, growing epitaxially along the edges of the calcite (product of the carbonation of Ca(OH)2), and advancing inward aided by atomic defects (grain boundaries, stacking faults). In addition, high‐resolution transmission electron microscopy tools and electron diffraction simulation confirmed a monoclinic symmetry for afwillite crystals. These results contribute to analyzing the presence of crystalline/amorphous C–S–H in lime mortars, providing information on the structure of afwillite and its possible effects on the binder materials.

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Molecular dynamics simulation to assess the effect of temperature on diffusion coefficients of different ions and water molecules in C-S-H

Cited by 22 publications

References 57 publications

Assessing Hydrated Cement Paste Properties Using Experimentally Informed Discrete Models

Assessing Hydrated Cement Paste Properties Using Experimentally Informed Discrete Models

Cement and Concrete for Nuclear Waste Management

Evolution of C–S–H in lime mortars with nanoparticles: Nanostructural analysis of afwillite growth mechanisms by HRTEM

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