Dehydration and dehydroxylation of C-S-H phases synthesized on silicon wafers

Giraudo, Nicolas; Bergdolt, Samuel; Laye, Fabrice; Krolla, Peter; Lahann, Joerg; Thissen, Peter

doi:10.1016/j.apsusc.2017.10.039

Cited by 23 publications

(19 citation statements)

References 48 publications

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“…As it can be seen in Figure B, the FT-IR spectra of the CSH phases shown beside the vibration modes associated with the presence of silicates are also ones related to carbonates (in ν as (C–O) with a maximum at 1487 cm –1 and δ(O–C–O) at 875 cm –1 ) . Furthermore, vibration modes corresponding to ν(Si–O) and δ(O–Si–O) were observed, which evidence the formation of the CSH phases . These phases are the starting point for all techniques applied in this work to passivate the surfaces.…”

Section: Resultsmentioning

confidence: 84%

“…17−19 As it can be seen in Figure 3B, the FT-IR spectra of the CSH phases shown beside the vibration modes associated with the presence of silicates are also ones related to carbonates (in ν as (C−O) with a maximum at 1487 cm −1 and δ(O−C−O) at 875 cm −1 ). 17 20 These phases are the starting point for all techniques applied in this work to passivate the surfaces. In the past, it has already been proposed that carbonates do not stop the corrosion of CSH phases.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Hydrophobic Properties of Calcium-Silicate Hydrates Doped with Rare-Earth Elements

Burek

Krause

Schwotzer

et al. 2018

ACS Sustainable Chem. Eng.

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In this study, the apparent relationship between the transport process and the surface chemistry of the Calcium-Silicate Hydrate (CSH) phases was investigated. For this purpose, a method was developed to synthesize ultrathin CSH phases to be used as a model substrate with the specific modification of their structure by introducing europium (Eu(III)). The structural and chemical changes during this Eu(III)-doping were observed by means of infrared spectroscopy (IR), Xray photoelectron spectroscopy (XPS), and time-resolved laser fluorescence spectroscopy (TRLFS). These alterations of the CSH phases led to significant changes in the surface chemistry and consequently to considerable variations in the interaction with water, as evidenced by measurements of the contact angles on the modified model substrates. Our results provide the basis for a more profound molecular understanding of reactive transport processes in cement-based systems. Furthermore, these results broaden the perspective of improving the stability of cement-based materials, which are subjected to the impact of aggressive aqueous environments through targeted modifications of the CSH phases.

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Section: Resultsmentioning

confidence: 84%

Section: ■ Results and Discussionmentioning

confidence: 99%

Hydrophobic Properties of Calcium-Silicate Hydrates Doped with Rare-Earth Elements

Burek

Krause

Schwotzer

et al. 2018

ACS Sustainable Chem. Eng.

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“…The peaks at 1266 cm −1 and 1187 cm −1 are attributed to the antisymmetric stretching vibration of Si−O−Si. 37 The sharp peak at 1582 cm −1 and a weak peak at 870 cm −1 can be correlated to the asymmetric and bending vibration of the C−O of the CO 3 2– group presented in the calcium silicate carbonate phase, respectively. 37,38 Since the damage process of the material always starts with the weakest parts, the first mechanism of energy absorption is observed during stretching of C−O bonds.…”

Section: Resultsmentioning

confidence: 99%

Effect of polymer-coated silica particles in a Portland cement matrix via in-situ infrared spectroscopy

Hafshejani

Feng

Wohlgemuth

et al. 2020

Journal of Composite Materials

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It is often of great importance in engineering to know precisely the properties of a material used with regard to its strength, its plasticity or its brittleness, its elasticity, and some other properties. For this purpose, material samples are tested in a tensile test by clamping the sample with a known starting cross-section in a tensile testing machine and loading it with a tensile force F. The force is then graphically displayed over the length change ΔL caused. This curve is called the force-extension diagram. In this study, a new measurement method enables for the first time, depending on the applied uniaxial stress, an insight at the atomic level into various energy dissipation processes at cement-based materials with the help of infrared spectroscopy. The samples are modified by adding SiO2 particles, which are coated by a polymer (PEG-MDI-DMPA) of different PEG molecular weights. Results show that elongating and breakage of [Formula: see text] and [Formula: see text] bonds play an essential role in the strain energy dissipation. Compared to the pure cement, the modified samples are affected more by elongating and breakage of [Formula: see text] as the admixture can effectively reduce the energy barrier of the hydrolytic reaction. The incorporating of particles into the cement matrix induces new mechanisms for energy dissipation by stretching of [Formula: see text] bending vibrations. Stretching vibration of the [Formula: see text] group indicates that part of the energy is dissipated by breakage of hydrogen bonding between the carboxyl group and PEG chains. Besides, a higher value of the ultimate fracture force following an increase in the molecular weight of PEG shows stronger bonding between particles and the cement matrix. As the chain-length of PEG is increased, less energy is absorbed through the other processes (especially at a higher level of strain). Thus, there is a balance between the whole deformation (toughness) and the strength of samples with the increase of the PEG molecular weight.

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“…The spectrum shows other vibration modes after the synthesis, corresponding to the Si–O (ν(Si–O) with a maximum at 976 cm –1 and δ(O–Si–O) at 660 and 460 cm –1 ), which is some evidence of the formation of the C–S–H phases. Additionally, the thickness was investigated by scanning electron microscopy and was measured around 400 nm; the surface of the layer shows a high roughness and a needlelike appearance . These phases are the starting point for all techniques that are applied in this work to passivate the surfaces.…”

Section: Resultsmentioning

confidence: 99%

“…The synthesis of calcium silicates on silicon wafers was described before as a versatile tool for atomic understanding. , In this paper, these ultrathin layers are the key substrates to investigating the passivation techniques with different molecules. As was mentioned before, the carbonate’s termination impedes the reaction of many molecules with the surface.…”

Section: Introductionmentioning

confidence: 99%

Passivation of Hydrated Cement

Giraudo

Wohlgemuth

Bergdolt

et al. 2017

ACS Sustainable Chem. Eng.

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Interface phenomena are the starting point for every corrosion reaction. In this work, the corrosion of calcium−silicate−hydrate (C−S−H) phases by water is investigated by implementing silicon wafers as substrates. The carbonation of these phases was avoided by synthesizing the samples in a controlled atmosphere. The passivation of these mineral surfaces is a significant step for materials sustainability. The coating of the surfaces with four different molecules is presented here: carbonation, sodium silicate layers, tetraethyl orthosilicates (TEOS), and octadecylphosphonic acid (ODPA) monolayers. The performance of every technique against corrosion by water is evaluated by infrared spectroscopy, inductively coupled plasma optical emission spectroscopy, water contact angle, and pH measurements. Since the concentration of protons in water is the relevant parameter in this corrosion process, three different values were analyzed at the experiments. After comparing the passivation techniques, the results obtained by coating with ODPA are the most promising ones, and it is, therefore, applied to a more realistic model: hydrated cement. The passivation by ODPA is then analyzed to unravel the mechanism of hydrophobization, finding its dependence with the Ca/Si ratio of the surfaces, supported by first-principles calculations. The passivation by applying this kind of molecule is very promising because of its efficiency against water corrosion and due to the easiness of preparation of the surface before its application.

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Dehydration and dehydroxylation of C-S-H phases synthesized on silicon wafers

Cited by 23 publications

References 48 publications

Hydrophobic Properties of Calcium-Silicate Hydrates Doped with Rare-Earth Elements

Hydrophobic Properties of Calcium-Silicate Hydrates Doped with Rare-Earth Elements

Effect of polymer-coated silica particles in a Portland cement matrix via in-situ infrared spectroscopy

Passivation of Hydrated Cement

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