Chloride sorption by C-S-H quantified by SEM-EDX image analysis

Georget, Fabien; Bénier, Calixe; Wilson, William; Scrivener, Karen

doi:10.1016/j.cemconres.2021.106656

Cited by 32 publications

(11 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Steps were taken during the compaction process to ensure that maximum theoretical density could be reached for the samples without resulting in damage to the die press. Due to the larger particle size of the SiO 2 powder, the predicted theoretical densification for compaction of the pellets leveled out at ∼70% fractional volume 43 . Pressureless sintering was carried out at 1800°C for 5 h, and the finished samples were later cast into epoxy to support the samples during subsequent polishing and indentation.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

On the role of continuity in statistical nanoindentation of composite microstructures

2022

View full text Add to dashboard Cite

The validity of the statistical nanoindentation (SNI) technique for cementitious materials has been questioned by numerous researchers; however, it is still a commonly used method in literature. This study revisits assumptions pertaining to continuum mechanics of the method by using a well-established selective SNI method to evaluate continuity in the mechanical response of each indent. Ordinary portland cement (OPC) was investigated alongside a two-phase aluminosilicate ceramic (Al-Si). Filtering for continuity of indents eliminated a majority of indents in each sample. The indents meeting continuity requirements in the OPC sample had moduli values in the range of documented calcium silicate hydrates and portlandite-the predominant hydration phases in OPC. In the Al-Si sample, 73% of continuous indents were assigned to a mullite phase, although the chemical analysis showed only 42% mullite. This was attributed to the embedded morphology of the mullite phase, which made it more susceptible to structural compliance. These observations suggest that SNI may be ineffective for measuring the mechanical properties of individual phases in a microstructure if they are not prolific enough to exhibit a continuous indent response. Discontinuous indents due to microstructural interaction between phases were also shown to have a potential influence on the number of clusters (i.e., phases) suggested by the deconvolution algorithms.

show abstract

Section: Methodsmentioning

confidence: 99%

“…This is consistent with other polishing procedures for cement microscopy, which include frequent sample rinsing. 42 The recommended mirror finish for nanoindentation 41 was obtained from the procedure.…”

Section: Preparation Of Opc Samplementioning

confidence: 99%

On the role of continuity in statistical nanoindentation of composite microstructures

2022

View full text Add to dashboard Cite

show abstract

“…However, these phases are also difficult to quantify by SEM-EDS due to the intrinsic resolution limitations. 3,5,22,40 Nevertheless, it is important to note that SEM-EDS could be one of the only methods able to identify, and quantify the fraction of low-density (LD) and high-density (HD) C-S-H in complex microstructures 12,41,42 as the use of adsorption techniques is limited when other mesoporous SCMs are available (such as metakaolin). However, these C-S-H 'types' can be identified by EDS image analysis.…”

Section: Morphology and Microstructure Descriptorsmentioning

confidence: 99%

“…29 The binding of contaminants is also crucial for the investigation of chloride ingress. Chloride can bind both on the C-S-H 23,42 and the AFm, 58,59 and quantifying the binding is crucial to properly validate reactive transport models for chloride. Although other methods exist, none are very precise, and SEM-EDS can be used as a cross-validation.…”

Section: Quantification Of the Stoichiometry Of Solid Phasesmentioning

confidence: 99%

A critical catalogue of SEM‐EDS multispectral maps analysis methods and their application to hydrated cementitious materials

Georget,

Schmatz,

Wellmann

et al. 2023

Journal of Microscopy

Self Cite

View full text Add to dashboard Cite

Many methods have been proposed to analyse SEM‐EDS hypermaps of hydrated cementitious materials but none can fit all purposes. In this presentation, we review existing methods for phase identification, stoichiometry quantification, and microstructure quantification in cementitious materials and related materials. We first discuss the unique contribution of SEM‐EDS with respect to the outstanding scientific challenges towards sustainable construction materials. We then compare the SEM‐EDS and image analysis techniques which contribute to answering these challenges. Convergence and divergence in current methods and workflows, and knowledge gaps are highlighted in terms of the specificities of the material (phase assemblage complexity, grain sizes, mixtures, etc.). The discussion is weighted by the required expert knowledge for the sample preparation, microscope operation, and data analysis. We conclude by discussing how microscopy and image analysis integrate into the overall experimental toolkit to investigate and improve cementitious materials.

show abstract

“…-With respect to the bound and free chlorides, in [35] is studied several cases of chloride isotherms, resulting that a solid solution is found between the Friedel's salt and hemicarboaluminate, together with the known fact that chlorides are adsorbed on the calcium silicate gel, pointing out that the method of measurement of the free and bound chlorides are a key aspect for the correct quantification. Authors in [36] also studied the effect of the testing condition defining that the isotherms have been studied in a diluted solution which affects the equilibrium of free/bound chlorides and also modifies the pH of the solution.…”

Section: Introductionmentioning

confidence: 99%

Finite Boundary Conditions Due to the Bar Presence in the Model of Chloride Penetration

Tavares

Andrade

2022

Materials

View full text Add to dashboard Cite

The chloride penetration is usually modelled through the application of a solution of Fick’s second law of diffusion, based on the assumption of semi-infinite boundary conditions. However, the presence of the bars, on whose surface the chlorides accumulate, makes this assumption incorrect. As the time progresses, the chlorides in the steel/concrete interface increase in concentration more than the chlorides overpassing the bar position without obstacles. This circumstance, although previously studied, has not been introduced in common practice, in spite of it supposes early reaching of the chloride threshold. The study in this paper shows a deterministic analysis of the chloride diffusion process by the finite element method (FEM) which numerically solves Fick’s second law, taking into account the accumulation of the chlorides on the bar surface. Several examples are calculated and factors between the finite/semi-infinite solutions are given. These factors depend on the cover depth and the diffusion coefficient, and with less importance, on the diameter of the bar, which make it unfeasible to propose a general trend.

show abstract

Chloride sorption by C-S-H quantified by SEM-EDX image analysis

Cited by 32 publications

References 30 publications

On the role of continuity in statistical nanoindentation of composite microstructures

On the role of continuity in statistical nanoindentation of composite microstructures

A critical catalogue of SEM‐EDS multispectral maps analysis methods and their application to hydrated cementitious materials

Finite Boundary Conditions Due to the Bar Presence in the Model of Chloride Penetration

Contact Info

Product

Resources

About