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Research article
I Rorig-Dalgaard
Technical University of Denmark, Department of Civil Engineering
Corresponding Author
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This work is licensed under a CC BY 4.0 License. Read Full License
Accelerated salt-induced deterioration occurs by frequent changes across the equilibrium relative humidity (RH eq ). Therefore, knowledge of the actual RH eq of a salt mixture has a major impact on preventive conservation to ensure that the relative humidity (RH) does not cause a salt phase transition and in situ desalination as the dissolution of salt is the essential criterion to enable transport of salt (ions) in materials.
For decades, it has been possible to determine the RH eq in salt mixtures with the user-friendly, thermodynamic-based ECOS-Runsalt software. However, the ECOS-Runsalt model is challenged by the influence of kinetics along with some limitations in regard to possible ion types and combinations.
A dynamic vapor sorption (DVS) instrument is used for the direct measurement of RH eq and to deduce knowledge on the physicochemical nonequilibrium process related to the phase changes in salt mixtures. The experimentally measured RH eq values in this study of NaCl-Na 2 SO 4 -NaNO3, NaNO 3 -Na 2 SO 4 , NaCl-NaNO 3 , NaCl-Na 2 SO 4 , and (NH 4 ) 2 SO 4 -Na 2 SO 4 are in agreement with values from the literature. A comparison with thermodynamically calculated results makes it probable that the phase transition for some salts is significantly influenced by nonequilibrium conditions.
The present work bridges some of the existing gaps in regard to accuracy, including the effects of kinetics and the possible ions and combinations that may be found in situ. The proposed method makes it possible to determine a more representative RH eq in relation to real conditions for the improved treatment of salt-infected constructs.
Keywords
Equilibrium relative humidity, salt mixtures, dynamic vapor sorption instrument, metastable phases
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A new preprint design is coming!
We have improved readability, clarity, accessibility, and opportunities for engagement.
This is a preprint, a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Research article
I Rorig-Dalgaard
Technical University of Denmark, Department of Civil Engineering
Corresponding Author
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
History
CURRENT STATUS: Posted
Version 1
Posted 18 Jan, 2021
No community comments so far
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Accelerated salt-induced deterioration occurs by frequent changes across the equilibrium relative humidity (RH eq ). Therefore, knowledge of the actual RH eq of a salt mixture has a major impact on preventive conservation to ensure that the relative humidity (RH) does not cause a salt phase transition and in situ desalination as the dissolution of salt is the essential criterion to enable transport of salt (ions) in materials.
For decades, it has been possible to determine the RH eq in salt mixtures with the user-friendly, thermodynamic-based ECOS-Runsalt software. However, the ECOS-Runsalt model is challenged by the influence of kinetics along with some limitations in regard to possible ion types and combinations.
A dynamic vapor sorption (DVS) instrument is used for the direct measurement of RH eq and to deduce knowledge on the physicochemical nonequilibrium process related to the phase changes in salt mixtures. The experimentally measured RH eq values in this study of NaCl-Na 2 SO 4 -NaNO3, NaNO 3 -Na 2 SO 4 , NaCl-NaNO 3 , NaCl-Na 2 SO 4 , and (NH 4 ) 2 SO 4 -Na 2 SO 4 are in agreement with values from the literature. A comparison with thermodynamically calculated results makes it probable that the phase transition for some salts is significantly influenced by nonequilibrium conditions.
The present work bridges some of the existing gaps in regard to accuracy, including the effects of kinetics and the possible ions and combinations that may be found in situ. The proposed method makes it possible to determine a more representative RH eq in relation to real conditions for the improved treatment of salt-infected constructs.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
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