Research article

An overview of hydrophobic treatments and their application with Internal Wall Insulation

Authors
  • Toby Cambray orcid logo (Institute for Environmental Design and Engineering, University College London)
  • Valentina Marincioni orcid logo (Institute for Environmental Design and Engineering, University College London)
  • Hector Altamirano orcid logo (Institute for Environmental Design and Engineering, University College London)

This article is a preprint and is currently undergoing peer review by UCL Open: Environment.

Abstract

Hydrophobic (or water-repellent) treatments have been proposed to mitigate moisture risks associated with Internal Wall Insulation when applied to solid masonry walls. This can reduce risks associated with moisture accumulation within the structure such as mould growth or the deterioration of joist ends and other embedded timber. However, such treatments slow down drying processes, and therefore may result in a net increase in moisture if the treatment is bypassed by e.g. cracks. Furthermore, such treatments have been linked with damage to external masonry surfaces. Freeze-thaw and salt crystallisation are the two main causes. Hygrothermal simulations may give some indication of risks but techniques to assess surface damage are either simplistic, impractical outside of the research environment, or both.

Keywords: Hygrothermal, Sustainability in architecture and the built environment, Solid Wall Insulation, Water repellent, Energy and climate, Hydrophobic, Internal Wall Insulation

Preprint Under Review

 Open peer review from Nathan Van Den Bossche

Reviewer: Nathan Van Den Bossche
ORCID: orcid logo https://orcid.org/http://orcid.org/0000-0002-8738-7249
DOI: 10.14293/S2199-1006.1.SOR-MATSCI.A9TQXW.v1.RNJYGE
Date Completed: 2022-06-03

Review

Review information

DOI:: 10.14293/S2199-1006.1.SOR-MATSCI.A9TQXW.v1.RNJYGE
License:
This work has been published open access under Creative Commons Attribution License CC BY 4.0 , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Conditions, terms of use and publishing policy can be found at www.scienceopen.com .

ScienceOpen disciplines: Materials technology , Engineering , Architecture
Keywords: Water repellent , Internal Wall Insulation , Solid Wall Insulation , Energy and climate , Hygrothermal , Sustainability in architecture and the built environment , Hydrophobic

Review text

A very comprehensive piece of work indeed. Worth while reading. It compiles a range of relevant aspects and gives insights in the challenges at hand. It reads like an introductory chapter in a textbook and I would happily recommend it to a lot of people. However, it does not provide a complete state of the art literature review with adequate detail for what has been done before, and it does not add new data to the field. In that respect I would consider it as a very good conference paper, but it would not qualify for a high-ranked scientific journal.

I have no major remarks, just some minor editorial remarks and little points of discussion:

Section 3.1, the last sentence is just “Lubelli”, whereas a reference to literature was probably intended here?

Section 4.1.1 typo error in the first word.

Section 4.1.2 Reason 4: Although I agree with the processes that may affect capillary absorption tests, the impact of these phenomena should not be overestimated. Ideally, this section would also comprise a quantitative discussion on the topic to put these effects in the right perspective.

Section 4.1.2 Reason 5: it should be noted that in cup test measurements there can be some liquid moisture transfer, but that does not compromise the validity of the measurement (in contrast to reason 4). It only highlights the artificial separation of liquid and vapor transfer. Next to that, this entails that the typical decrease in water vapor resistance of materials at higher moisture contents may be less evident for materials with HPT.

Section 4.2.1 In the first sentence there is a single “ which is confusing.

Section 4.2.1, page 9, 4 th paragraph. “In the capillary tube experiment” = Karsten tube?

Section 4.2.2 2 nd paragraph. The last sentence states that the impact of surface roughness “contradicts the previous statement”. However, it is not clear which aspects contradict each other.

Section 4.2.2 Last paragraph: some materials do not display the first drying phase. It would be relevant to provide practical examples.

Section 5. 3 rd paragraph: “the wall is generally direr” => drier

Section 5. 3 rd paragraph: last sentence is incomplete

Section 6. 4 th paragraph, 1 sentence: ad > and

Section 6.2 It seems rather obvious that out of the three modelling approaches, the one in which different material properties are adopted for the thickness of the treated layer is most reliable. The paper seems to accept the approach where the whole masonry is assumed to be hydrophobic.

Section 7. 6 th paragraph. “The risk of frost damage can indicated by” > be indicated by



License: Creative Commons Attribution 4.0

Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. No additional restrictions — You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits.

Note:
This review refers to round 1 of peer review and may pertain to an earlier version of the document.

 Open peer review from Ernst Jan de Place Hansen

Reviewer: Ernst Jan de Place Hansen
ORCID: orcid logo https://orcid.org/http://orcid.org/0000-0002-6906-3793
DOI: 10.14293/S2199-1006.1.SOR-MATSCI.AVVBCL.v1.RJDOYP
Date Completed: 2022-10-09

Review

Review information

DOI:: 10.14293/S2199-1006.1.SOR-MATSCI.AVVBCL.v1.RJDOYP
License:
This work has been published open access under Creative Commons Attribution License CC BY 4.0 , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Conditions, terms of use and publishing policy can be found at www.scienceopen.com .

ScienceOpen disciplines: Materials technology , Engineering , Architecture
Keywords: Water repellent , Internal Wall Insulation , Solid Wall Insulation , Energy and climate , Hygrothermal , Sustainability in architecture and the built environment , Hydrophobic

Review text

On one hand an interesting overview on hydrophobic treatment of internally insulated walls, that could be a good introduction if you are not familiar with the topic. Written in a way that makes it easy to read. On the other hand, it is not clear to me what the purpose of the paper is and what it adds to the present literature on hydrophobic treatment. The paper covers too many subjects which means that it does not go deep into any of them. Like Nathan, I would therefore consider it as a good conference paper, but it would not qualify for a high-ranked scientific journal.

My specific comments are split in two parts; the first part contains suggestions to improve the content of the paper, while the second part contains some editorial comments.

Suggestions to improve the paper:

Section 3.2 – 3.5 should be rewritten; I suggest to use the references as a support to your main story (which I have not identified, cf. my introductory comment). The present setup presents a lot of details without bringing these into an overall story.

Section 3.3, concerning timing of interventions: please add https://doi.org/10.1016/j.buildenv.2020.107410 as reference.

Switch order of 4.1 and 4.2.

Section 4.1.2 is quite detailed compared with other sections of this paper; consider to rewrite the section and refer the different theories to each other, i.e. including your own opinion, not only referring previous studies (referring also to my comment regarding section 3.2-3.5).

Section 4.2.2: Why do you present the two-stage process in such a detail? This should be common knowledge.

Section 4.3.2, last paragraph, last sentence: To my knowledge nobody relate breathability to include liquid transport. Consider to rewrite.

Section 4.3.3, 2 nd paragraph, last sentence: add ‘or reduction of liquid absorption (Soulios et al, 2020)’.

Section 5, 4 th paragraph, 1 st line: Why do you write ‘perhaps’; explain why these mechanisms are the most important. i.e. why you focus on these in section 5 (this could be explained in the introduction, explaining the structure of the paper).

Section 5.2: According to the headline this is about cryptofloresence, however this is not defined until the last part of second paragraph, after defining another important parameter. Please frontload the definition of cryptofloresence or reconsider the title of this section. In section 5.1, it is labelled ‘damage due to the expansion of salt crystals’.

Section 6, 6 th paragraph: Also Soulios has modelled a hydrophobized brick; refer to 10.1016/j.buildenv.2020.107410 (Soulios, de Place Hansen and Peuhkuri, 2021) and (Soulios 2021) Hygrothermal Performance of Hydrophobized Brick and Mortar: Energy Renovation Through Internal Insulation - Can Hydrophobization Improve the Moisture Safety? Phd. Thesis, Aalborg University 10.54337/aau459966346

Section 6.1-6.3 should be supported by more references to support your statements / discussions.

Section 6.3, last sentence: What you state here as a need was studied by Soulios in the two references mentioned above.

Section 7: Please make this section shorter and less detailed. It should focus on the main findings, not repeating the discussions in previous sections. And add a paragraph indicating the next step; what do you suggest to study further?

Section 5.1, 4 th paragraph:

This paragraph should be expanded, as several authors have studied freezing mechanism over the years, e.g. (Powers & Helmuth, 1953), (Litvan, 1972) and (Setzer, 1977). Also, a reference to thresholds values for frost damage expressed by the critical degree of saturation developed by Fagerlund (1977) would be relevant to add. Critical degree of saturation is shown to be strongly related to porosity and pore size distribution, e.g. (Maage, 1984). Also note that not only the freezing point but also the freeze-thaw behaviour / mechanism is affected by the presence of salts, see e.g. (Springenschmid, 1969, 1972), (Jungwirth, Bayer & Grübl, 1986).

References:

Fagerlund, G. (1977). The critical degree of starvation method of assessing the free/thaw resistance of concrete. Materials and Structures , vol. 10, no. 58, pp. 217-253.

Jungwirth D., Beyer, E., & Grübl, P. (1986). Dauerhafte Betonbauwerke. Substanzerhaltung und Schadensvermeidung in Forschung und Praksis . Beton-Verlag, Düsseldorf.

Litvan, G.G. (1972). Phase transitions of adsorbates: III, Heat effects and dimensional changes in nonequilibrium temperature cycles. J. Colloid Interface Science , vol. 38, no. 1, pp. 75-83.

Maage, M. (1984). Frost resistance and pore size distribution in bricks. Materials and Structures , vol. 17, no. 101, pp. 345-350.

Powers, T.C. & Helmuth, R.A. (1953). Theory of volume changes in hydrated Portland cement paste during freezing. Proc. Highway Research Board , vol. 32, pp. 285-297.

Setzer, M.J. (1977). Einfluss des Wassergehaltes auf die Eigenschaften des erhärteten Betons. Deutsche Ausschuss für Stahlbeton, Heft 280 , Berlin.

Springenschmid, R. (1969). Grundlagen und Praxis der Herstellung und Überwachung von Luftporenbeton. Zement und Beton , vol. 15, pp. 19-25.

Springenschmid, R. (1972). Erfahrungen bei der Verwendung von Luftporenbildern im Strassenbau. Betonwerk + Fertigteil-Technik , vol. 38, no. 8, 587-593.

I am not familiar with (Künzel, 1995) and (Sedbauer and Künzel, 2000) referred in the paper and whether they refer to the different theories on frost degradation etc., covered by the above-mentioned references, included in my PhD-thesis in frost resistance (published in 1996, in Danish unfortunately).

Further, I could suggest to study section 4.3 in report D2.2 from the RIBuild project on internal insulation of historic buildings (look for the Knowledge Base -> Research at https://www.ribuild.eu/knowledge-base/#research )

Editorial remarks not already covered by a previous review by Nathan Van Den Bossche:

When listing several references to support a statement: Consider listing references with the newest first. And be careful not to list too many references, as in the last paragraph of Section 3.4.

Section 3.1, 2 nd paragraph: Check the used of ‘(SPAB,1995)’ in first line.

Section 3.2:
Is ‘the treatments was usually missing’ referring to van Hees?
Is the phrase ‘The research presented’ referring to the three references already mentioned? In the same sentence, something is missing between ‘hygrothermal performance’ and ‘consumption rate’. And replace ‘are’ with ‘is’ after ‘impregnation’.

Section 3.3: Check the grammar in 2 nd sentence.

Section 3.4: replace ‘depth’ with ‘Depth’ in 3 rd line.

Section 4.1.1, 2 nd paragraph:
Is ‘This means’ referring to hydrophobic or hydrophilic? And please check the grammar of this sentence.
The text in the parenthesis in 2 nd sentence is superfluous.
In the last sentence please add ‘with water repellants’ after ‘treatment’.

Section 4.1.2, last sentence: Is ‘small amount of residual absorption’ referring to absorption still being present or that it is reduced heavily?

Section 4.2.1,1 st sentence after the bullet lists, 5 th line: Should ‘where’ be replaced by ‘whether’?

Section 4.2.1, 2 nd paragraph after the bullet lists:  replace ‘(Krus, 1998)’ to the end of the sentence.

Section 4.2.1, 3 rd paragraph after the bullet lists, 4 th line: delete ‘the’ in front of ‘moisture’.

Section 4.2.1, 5 th paragraph after the bullet lists, 4 th line: Delete ‘).’
Do. Last sentence: what is ‘this type’ referring to? Please specify.

Section 4.2.1, last paragraph: Be more specific than simply referring to ‘below’.

Section 4.2.2, 1 st paragraph: Delete 2 nd sentence as you refer to this study in the following paragraphs.

Section 4.3.2, last paragraph, 5 th line: ‘only a small impact’; do you mean that the treatment does not affect breathability significantly?

Section 4.3.3, 2 nd paragraph, 3 rd line: delete ‘is’ after ’50mm)’.

Section 4.3.3, 2 nd paragraph the sentence starting at 5 th line: Please replace ‘because’ with ‘as this is directly linked with’, and delete ‘is directly linked’.

Section 5: Add a level 2 headline (5.1) right after the level 1 headline (5).

Section 5, 4 th paragraph, 1 st line: ‘to the external surfaces of masonry’ => surface.

Section 5.1: Merge the two (or three) first paragraphs.

Section 5.1, 5 th paragraph: Which mechanism do you refer to in the last sentence?

Section 5.2: Please use either ‘efflorescense’ or ‘effloresence’. At present, both are used. Similar with ‘cryptofloresence’.

Section 6: Add a level 2 headline (6.1) right after the level 1 headline (6).

Section 6, 1 st paragraph, 5 th line: Please specify which techniques you refer to.

Section 6.2, 1 st paragraph: What does ‘Alle three approaches’ refer to?

Section 6.2, 3 rd paragraph, 4 th line: delete ‘is’ after the parenthesis.

Section 7, 7 th section: This should be placed earlier in section 7.

References: Please use ‘de Place Hansen, E.J.’ in the three references with Soulios as first author, and in (Hansen, Hansen and Soulios, 2021).



License: Creative Commons Attribution 4.0

Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. No additional restrictions — You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits.

Note:
This review refers to round 1 of peer review and may pertain to an earlier version of the document.

 Open peer review from Nathan Van Den Bossche

Reviewer: Nathan Van Den Bossche
ORCID: orcid logo https://orcid.org/http://orcid.org/0000-0002-8738-7249
DOI: 10.14293/S2199-1006.1.SOR-MATSCI.AAHGOX.v1.RPVVTB
Date Completed: 2022-12-20

Review

Review information

DOI:: 10.14293/S2199-1006.1.SOR-MATSCI.AAHGOX.v1.RPVVTB
License:
This work has been published open access under Creative Commons Attribution License CC BY 4.0 , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Conditions, terms of use and publishing policy can be found at www.scienceopen.com .

ScienceOpen disciplines: Materials technology , Engineering , Architecture
Keywords: Water repellent , Internal Wall Insulation , Solid Wall Insulation , Energy and climate , Hygrothermal , Sustainability in architecture and the built environment , Hydrophobic

Review text

In general, the same comments apply compared to the previous version. It is an well-written paper that gives a good introduction to HPT. However, it does not add to the state of the art because no new information is provided, and level of literature review is insufficient to derive important new conclusions from that. Hence, this paper would not qualify for a high-impact scientific journal. Given that the concept of UCL open is a bit unclear to me, I leave it up to the editor to decide whether this aligns with the goals of the journal.

The title is slightly misleading, as one might expect “an overview of hydrophobic treatments”, which is not the case. The paper does not focus on the different types of treatments that are used, so I would be inclined to rephrase the title.

Section 3: the first sentence comprises “summarizes” twice, and as well, is a bit problematic. “briefly summarizes some key literature, grouped in a series of topics”. Given that the abstract explicitly states that this paper provides a state-of-the-art, there seems to be a mismatch between the ambition formulated there, and the “briefly”, “some”. As indicated in the first review, this paper is worth while reading and provides a good introduction in the topic, but does not qualify as a lasting contribution to the state-of-the-art.

Section 4.1.1 This section is rather qualitative in nature, and lacks quantitative underpinning. This is mainly because rather generic concepts are introduced which should be known to the majority of the readers. May I refer to e.g. following paper: DOI: 10.1177/17442591211009937. The section on hydrophobic treatments investigates the impact of rain water leakage into the construction, and how that affects freeze-thaw risks and mould for a wall with HPT.

Section 4.3.2, 3 rd paragraph: the last sentence is incomplete “The role of the depth of penetration on wetting and drying”.

Section 6.3: note that the 1% rule is a bit outdated, and several publications have been filed that provide an overview of more realistic infiltration rate, e.g.

https://doi.org/10.1016/j.buildenv.2022.109213



License: Creative Commons Attribution 4.0

Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. No additional restrictions — You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits.

Note:
This review refers to round 2 of peer review and may pertain to an earlier version of the document.