PONE-D-22-27578Evaluation of near-infrared spectroscopy as a contactless method for health monitoring of coating materials applied to concrete surfacesPLOS ONE

Dear Dr. Watanabe,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. Please read the comments raised by the respected reviewers and address all of them systematically.

Please submit your revised manuscript by May 04 2023 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

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We look forward to receiving your revised manuscript.

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Khalil Abdelrazek Khalil, Ph.D.

Academic Editor

PLOS ONE

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Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: No

Reviewer #3: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: N/A

Reviewer #3: N/A

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: No

Reviewer #3: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: No

Reviewer #3: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: This article presents a good nondestructive method to track the deterioration of coatings applied to concrete surfaces. it would be of interest to many readers and i recommend accepting it after considering the following revisions:

- Lines 197-199: The authors mentioned “Given the annual amount of outdoor UV in the wavelength range of 300–400 nm, based on JIS 9110, these conditions produce deterioration equivalent to that produced by seven years of outdoor weathering”, please mention the JIS or the ASTM standards that the mentioned conditions are equivalent to “seven years of outdoor weathering”

- Line 238: please mention the JIS or the ASTM standards used with the “salt-water immersion test”.

- Lines 296-298: the authors mentioned “The reduction in the absorption intensity of the peak at 2345 nm is particularly stark compared to the peak at 2350 nm, indicating that the C-H bond is more easily broken by UV irradiation”. While in the FTIR section, lines 326-327, it is mentioned “Based on the location of these peaks, this decrease appears to indicate alkyl group cleavage”. I wonder if the results from NIR and FTIR support each others as the alkyl groups cleavage conclusion would reflect more of C-C bonds breakage rather than the C-H bonds cleavage reveled by the NIR. Please elaborate more on the results and explain more if the results from both techniques are supporting each others.

- Lines 426-427: The authors mentioned “These properties highlight the potential of NIRS as a simple, inexpensive method for inspection of surface coating materials.”. I wonder if the technique can be simply used by engineers in the filed without the need of sending some samples to labs for the SEM-EDX pictures. As it seems to me that the SEM-EDX results were also crucial to confirm the results from both the NIR and FTIR techniques, please comment on this part.

- I recommend the authors to conduct extended UV exposure beyond the 396 hours used herein as great extent of degradation might happen after 500 hours for example. Also, it would be better if the author can design a set up in which the samples get exposed to both salty water and UV simultaneously, as this combined effect might alter the coating greatly and it’s more meaningful and mimics exactly what would happen in real life, rather than the effect of UV or salt water alone.

Reviewer #2: This manuscript reports the results of an interesting research. However, I do not recommend accepting it in the present form due to various problems as described below.

The title and the short title indicate quite different contents. Judging from the title and abstract, the goal of this study is to prove that near-infrared spectroscopy can be used to evaluate the state of deterioration of coatings on concrete surfaces. However, no clear conclusion based on convincing evidence is presented. This is the main flaw of this manuscript.

Consideration on the following points is also needed.

(1) LL. 206-208: Please specify how the infrared spectrum was used to interpret the near-infrared spectrum. In this paper, near-infrared and infrared spectra are shown, respectively, in nm units and in cm-1 units, so their comparison is difficult. Use of the same units (cm-1) is recommended.

(2) LL. 281-283: Isn’t the spectrum of the underlying mortar observed not because the resin on the mortar is not even, but because the resin is so thin that near-infrared light is transmitted through it? Or was the uneven resin on the mortar concluded by the photos shown in Fig. 2?

(3) LL. 292-298: For all the spectra in Fig. 3, strong absorption of the substrate is observed suggesting that most of the coating has been lost for all samples. This is not consistent with the description in the previous paragraph.

The bands at 2345 and 2350 nm cannot be distinguished.

(4) LL. 298-301: Stating this leads that there is no basis for discussion.

(5) LL.319-320: What is the absorption at 2512 cm-1 assigned to? No significant absorption should be observed in this region usually. Is the absorption due to a component that does not change in the deterioration process and can be used for the standard?

(6) LL. 320-323: Please assign the bands clearly.

(7) LL.324-326: Please clarify which bands show similar changes by quantitative evidence.

(8) LL.327-329: Please indicate what kinds of reaction you expect.

(9) The descriptions in Sections 3.3 to 3.5 have little relation to the results of the near-infrared spectroscopy. Their relation to the main target of this manuscript cannot be understood.

(10) Only the obvious conclusion that needs no discussion is stated in section 3.6.

(11) Followings should also be revised.

･ There are many spelling mistakes, grammatical mistakes, and unnatural English expressions.

･ It is necessary to indicate what JIS is.

･ L.250: Since the SI system of units does not allow the use of M for molarity, it is recommended to use mol L-1.

･ Figs. 1, 3, 4, 9, and 10: Label for horizontal axis should be below the spectrum. It is easier to distinguish the spectra by not only distinguishing them by color, but also by adding symbols such as a, b, c, ･･･.

Reviewer #3: This paper reports the results of a study to demonstrate that NIR spectrometry can be used to inspect defects in protective coatings of concrete, including those due to ageing. The experimental design was properly set up and executed; the results are convincing and well discussed. I therefore recommend publication of this paper with some minor modifications:

- line 74: the authors mention pharmacy as a field of use of NIRS, whereas there are many others, such as synthetic chemistry (e.g. polymers), petrochemistry, food processing, etc. This passage should be amended accordingly.

- line 78: the authors write that each functional group absorbs at a unique wavelength, but this is not entirely true. True, the absorption peaks are quite sharp in the MIR, but they span several wavelengths.

- line 93: change stategic by strategic

- lines 281 - 285: the discussion suggests that the observed spectral mixing comes from lack of coverage of the protective agent. But the mixing may also be due to the fact that the light has passed through several layers of product. The few sentences in this passage could be changed in this sense, without changing the conclusion.

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Reviewer #1: Yes: Mohammad Hassan

Reviewer #2: No

Reviewer #3: Yes: Jean-Michel Roger

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PONE-D-22-27578R1Evaluation of near-infrared spectroscopy as a contactless method for health monitoring of coating materials applied to concrete surfacesPLOS ONE

Dear Dr. Watanabe,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Jun 24 2023 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Khalil Abdelrazek Khalil, Ph.D.

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #3: All comments have been addressed

Reviewer #4: (No Response)

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #3: (No Response)

Reviewer #4: Partly

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #3: (No Response)

Reviewer #4: I Don't Know

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4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #3: (No Response)

Reviewer #4: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #3: (No Response)

Reviewer #4: Yes

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #3: (No Response)

Reviewer #4: Manuscript Number: PONE-D-22-27578R1

Evaluation of near-infrared spectroscopy as a contactless method for health monitoring of coating materials applied to concrete surfaces

The work proposes using NIR spectroscopy for characterization of coating materials applied to concrete. I suggest the authors to present what are these materials (resin-based materials) in the abstract. Also, perhaps this can be added to the title, to clarify to the audience the materials investigated. This would be important, considering the general knowledge (and also what the authors mention in the introduction) about the signals in the NIR spectra that are related to organic material.

Material and methods

Section 2.1. Please clarify the total number of samples investigated. Also, please clarify the number of samples used for calibration and validation, as it is mandatory to have an external validation dataset.

Results and discussion

As the authors present, the main test for the degradation was the water-permeability, and water has a signal on NIR spectra. Hence, it seems that the main determination is actually the presence of water in the coatings. I suggest the authors to clarify this information, and enhance the discussion, considering this aspect.

Previous works have used NIRS to determine the mechanical properties of different materials. However, the mechanical properties are correlated to the composition of organic materials. Hence, I hereby list a few works on the subject (as a suggestion, the authors may find others) that may provide support for the discussion, stating that the main determination is actually the composition or presence of water, and it is correlated to the coating materials deterioration.

VIS–NIR spectroscopy as a process analytical technology for compositional characterization of film biopolymers and correlation with their mechanical properties - https://doi.org/10.1016/j.msec.2015.06.029

Application of VIS/NIR spectroscopy for estimating chemical, physical and mechanical properties of cork stoppers. Wood Sci Technol 48, 811–830 (2014). https://doi.org/10.1007/s00226-014-0642-3

Comparison of Methods for Estimating Mechanical Properties of Wood by NIR Spectroscopy - https://doi.org/10.1155/2018/4823285

I suggest to change the short title presented in line 4, page 1/58

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If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #3: Yes: Jean-Michel Roger

Reviewer #4: No

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[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Evaluation of near-infrared spectroscopy as a contactless method for health monitoring of resin-based coating materials applied to concrete surfaces

PONE-D-22-27578R2

Dear Dr. Watanabe,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Khalil Abdelrazek Khalil, Ph.D.

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #4: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #4: (No Response)

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #4: (No Response)

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4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #4: (No Response)

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #4: (No Response)

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #4: (No Response)

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #4: No

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