Quantification methods for chloride binding in Portland cement and limestone systems

Sui, Shiyu; Wilson, William; Georget, Fabien; Maraghechi, Hamed; Kazemi-Kamyab, Hadi; Sun, Wei; Scrivener, Karen

doi:10.1016/j.cemconres.2019.105864

Cited by 82 publications

(18 citation statements)

References 36 publications

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“…This can be done by SEM-EDS [28,30]. Alternatively, one could use the promising approach described in Maraghechi et al [7], Sui et al [31], and Avet et al [32], where they use Rietveld refinement X-ray diffraction (XRD-Rietveld) to both quantify the Friedel's salt and determine its Cl/Al ratio.…”

Section: Left)mentioning

confidence: 99%

“…XRD-Rietveld has been used by Sui et al [31] to quantify the amount of chloride-containing AFm and determine its composition as a solid solution of hemicarbonate and Friedel's salt. However, XRD-Rietveld analysis of AFm phases is very challenging because they are unstable during measurement, which leads to evaporation and/or carbonation.…”

Section: Afmmentioning

confidence: 99%

“…The chloride content in C(-A)-S-H in hydrated cement paste can be directly measured by determining the Cl/Ca or Cl/Si ratio of the C(-A)-S-H in polished sections using SEM-EDS [17,31,[58][59][60][61][62]. These ratios, combined with the quantification of the C(-A)-S-H content obtained by mass balance, for example, give the contribution of the chloride uptake by C(-A)-S-H to the total chloride content, which agrees well with the chloride taken up by C(-A)-S-H obtained with the above-mentioned elimination method [31,32].…”

Section: Chloride Adsorption In C(-a)-s-hmentioning

confidence: 99%

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Chloride binding in concrete: recent investigations and recognised knowledge gaps: RILEM Robert L’Hermite Medal Paper 2021

Weerdt

2021

Mater Struct

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A theoretical understanding of chloride binding is urgently needed if we are to use the new low-CO2 composite cements in reinforced concrete structures exposed to chloride-loaded environments. The empirical models and “deemed-to-satisfy” rules currently in use will not help in the face of the wide variety of new SCMs now being proposed. Engineers need generic chloride ingress models that can handle the variations in binder chemistry and exposure conditions. This paper reviews a selection of recent investigations by a team of NTNU researchers and international collaborators on various Portland composite cements using a combination of equilibrium chloride-binding experiments and thermodynamic modelling. One of our main findings is that “leaching” simulated by varying the pH and the calcium concentration has a dominant effect on chloride binding. However, challenges regarding the quantification and characterization of the chloride binding phases have yet to be overcome. To advance in this field we need additional crucial thermodynamic data for chloride-binding hydrates formed by low-CO2 cements containing SCMs, and we need to overcome some experimental challenges. A major break-through would come from understanding the interactions between chlorides and C(-A)-S-H. Part of the answer might be found at the atomic level. Finally, mechanistic numerical models are needed to upscale the findings from chloride binding to chloride ingress models. We conclude by showing the significance of such theoretical work on chloride binding for engineers tasked with the construction and maintenance of the reinforced concrete structures that are so vital a part of modern infrastructure.

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Section: Left)mentioning

confidence: 99%

Section: Afmmentioning

confidence: 99%

Section: Chloride Adsorption In C(-a)-s-hmentioning

confidence: 99%

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Chloride binding in concrete: recent investigations and recognised knowledge gaps: RILEM Robert L’Hermite Medal Paper 2021

Weerdt

2021

Mater Struct

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“…Limestone may react with calcium aluminate hydrates (C-A-H) in SCM blends to form carboaluminate hydrates, (monocarboaluminate (Mc, Ca4Al2(CO3)(OH)12•5H2O) and hemicarboaluminate (Hc, Ca4Al2(CO3)0.5(OH)13•5.5H2O) [106]). Ms, Mc, and Hc are all part of the monosulfate (AFm) family and can chemically bind chloride ions to form Friedel's salt (Fs, Ca4Al2Cl2(OH)12•4H2O) [106][107][108]. Ipavec et al [109] found that the chloride binding capacity of limestone cements is strongly dependent on the external solution's pH.…”

Section: Limestone In Chloride Bindingmentioning

confidence: 99%

CALTRANS: Impact of the Use of Portland-Limestone Cement on Concrete Performance as Plain or Reinforced Material

Bharawadj¹,

Chopperla²,

Choudhary³

et al. 2021

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“…[2Cl -, 4H 2 O]) (Grishchenko et al, 2013 (Bizzozero, 2014;Taylor, 1997). Friedel's salt, as a chloride-containing AFm phase, can be formed by the chemical reaction between chloride and some AFm phases like monosulfoaluminate, monocarboaluminate and hemicarboaluminate (Sui et al, 2019). In addition, AFm phases also belong to the lamellar double hydroxide family exhibiting typical hexagonal platelets morphology, and previous works also confirmed that Friedel's salt crystallizes in a hexagonal manner with a particle size of several microns (Birnin-Yauri and Glasser, 1998;Li et al, 2017a;Talero and Trusilewicz, 2012).…”

mentioning

confidence: 99%

Mechanism of strength evolution of seawater OPC pastes

Zhang

Sun

Zheng

et al. 2021

Advances in Structural Engineering

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This work investigated the strength degradation mechanisms of seawater ordinary Portland cement (OPC) pastes. Two types of specimens were prepared ((i) OSD sample (i.e. OPC was mixed with seawater, and then cured in deionized (DI) water) and (ii) ODD sample (i.e. OPC was mixed with DI water, and then cured in DI water, as the reference system)). The use of seawater in preparing OPC pastes effectively increased the hydration rate and early-age mechanical strength, but lowered the mechanical strength at the later age. The higher hydration degree and larger amounts of carbonates with a smaller crystal size enabled the seawater OPC pastes to exhibit a higher early-age mechanical strength, increasing by 13.0%–17.0% compared with the DI water OPC pastes. While the formation of Friedel’s salt and the formation of calcium-silicate-hydrate (C-S-H) gel with a lower polymerization degree and mean molecular chain length resulted in the deterioration of the pore structure and negatively affected the later-age strength development of the seawater OPC paste, decreasing by 5.8%–11.9% compared with the DI water OPC pastes.

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Quantification methods for chloride binding in Portland cement and limestone systems

Cited by 82 publications

References 36 publications

Chloride binding in concrete: recent investigations and recognised knowledge gaps: RILEM Robert L’Hermite Medal Paper 2021

Chloride binding in concrete: recent investigations and recognised knowledge gaps: RILEM Robert L’Hermite Medal Paper 2021

CALTRANS: Impact of the Use of Portland-Limestone Cement on Concrete Performance as Plain or Reinforced Material

Mechanism of strength evolution of seawater OPC pastes

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