Revolutionizing Construction Safety with Geopolymer Composites: Unveiling Advanced Techniques in Manufacturing Sandwich Steel Structures Using Formwork-Free Spray Technology

Round 1

Reviewer 1 Report (Previous Reviewer 2)

The authors study two geopolymer composites (solid and foam) as fire barriere coatings for steel constructions. The manuscript has greatly improved since last submission, however I still have some comments as listed below.

General comments:

Why is only two samples prepared? I believe it would be of interest to either studey effect of porosity (foam vs solid) or somehow change composition to optimize properties.

How was the composition of alkali-activated samples (Table 2) chosen?

Please comment on the crystallinity of the samples (table 4). What is the degree of crystallinity? Silica fumes consist of 51.1 % SiO2, however, the total SiO2 content almost 99 %, thus, these fumes must exhibit a high degree of disorder (amorphous structure).

How does the compressive strength of the GCs compare against the current solutions, e.g., Portland cement?

Why is the thermal conductivity considered worse for the foamed sample? I agree it is lower, but is a low thermal conductivity not a good thing in case of fire barriere?

The authors state in lines 362-363 that the fire resistance is affected by coating thickness. Where is that studied? Or is that based on a reference that is not cited? Otherwise, this would be of interest to study how thick a coating layer is necessary to obtain a certain fire barriere.

The conclusion should be corrected. The setting time has not been studied in this manuscript.

Specific comments:

GC should be introduced in line 35-

In lines 98-99, the thermal conductivity of basalt fibers are stated. I doubt the fiber itself after chopping has such low thermal conductivity.

Text related to Fig 1 and Tables 1 and 2 as well as table and figures should be moved to results as results are not to be discussed in experimental part.

All tables should include standard deviations for all determined values.

What is the unit of composition calculations in Table 2? This table is very unclear.

In section 2.2.1, no where it is stated that XRD is used, however, I assume it is XRD. Please clarify.

References 2 and 19 is the same.

Author Response

Dear Editor, Dear Reviewers,

Thank you for your prompt and detailed feedback. We have diligently revised our manuscript in line with the reviewers' comments. Our team is confident that these revisions have enhanced the quality of our work and aligned it with the standards of Coatings journal.

We trust that the updated manuscript is now ready for publication, and we eagerly await your final decision. Your guidance throughout this process has been invaluable, and we appreciate the opportunity to contribute to your esteemed publication.

Best regards,

Le Van Su

Author Response File: Author Response.pdf

Reviewer 2 Report (New Reviewer)

All abbreviations have to be expanded.

All company names must be added as references.

The significance of many sections such as particle size, chemical composition, XRD, etc must be explained. I do not see the need for these sections if you do not explain how this information will be used to explain the results.

The composition of Al is 100% alumina. Please check.

 Fig.7 is unclear. Where is the debonding area?

#3.4 is unclear. What does this statement mean " ..while the steel plate without the coating layer withstood only 3.78 minutes". 

Author Response

Dear Editor, Dear Reviewers,

Thank you for your prompt and detailed feedback. We have diligently revised our manuscript in line with the reviewers' comments. Our team is confident that these revisions have enhanced the quality of our work and aligned it with the standards of the Coatings journal.

We trust that the updated manuscript is now ready for publication, and we eagerly await your final decision. Your guidance throughout this process has been invaluable, and we appreciate the opportunity to contribute to your esteemed publication.

Best regards,

Le Van Su

Author Response File: Author Response.pdf

Reviewer 3 Report (New Reviewer)

This paper investigates the fabrication of geopolymer composites (GC) via spraying. The microstructure was examined by XRF and SEM, and comprehensive evaluation of the performance of GCs in the solid and foam forms as protection coating for steels was performed. The manuscript is well written and easy to read. The experimental methods were designed properly. The manuscript can be accepted after a minor question is address.

Although the authors have given sufficient scientific background in the introduction section, it will add in the strength of the paper if the authors can compare the performance of the obtained GCs with one or two mostly used protection coatings for steels, either using the data from the literature or from the authors’ experiments. This will allow the audience to better assess the potentials of GCs as a protection coating material.

Author Response

Dear Editor, Dear Reviewers,

Thank you for your prompt and detailed feedback. We have diligently revised our manuscript in line with the reviewers' comments. Our team is confident that these revisions have enhanced the quality of our work and aligned it with the standards of Coatings magazine.

We trust that the updated manuscript is now ready for publication, and we eagerly await your final decision. Your guidance throughout this process has been invaluable, and we appreciate the opportunity to contribute to your esteemed publication.

Best regards,

Le Van Su

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report (Previous Reviewer 2)

The authors replied well to my concerns, however, I wish some of the comments were also available in the manuscript and not only in the response letter.

Small suggestions to finalize the manuscript prior to acceptance:

1. Please clearly refer to your preliminary research in other journal papers when stating the composition (Table 1).

2. Please tell the readers that you are aware of a certain degree of amorphization in the samples, thus, the crystalline phases presented in Table 4 does not refer to the total of e.g. SiO2 as found by XRF. Thus discuss the difference in XRF and XRD.

3. Errors on values in Tables have not been provided for the measured values, only for averaged values. Errors on the measure crystalline compositions from Rietveld refinement is missing, and so is the error on the measured thermal conductivities.

Author Response

Dear Editor and Reviewer,

Thank you for your constructive feedback on my recent article submission. I have carefully considered your comments and made the necessary revisions to address your concerns. I believe the updated manuscript now meets the standards of the Coatings journal and hope it is suitable for acceptance. I appreciate the time and effort you have invested in reviewing my work. Your positive feedback has been invaluable, and I am hopeful that the amendments made will meet your expectations.

I am looking forward to your response.

Warm regards,

le van su

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

1. In the introduction, the authors failed to integrate the aim of the present work:  foaming, fire resistance, sprayed concrete, steel- 79 reinforced fly ash geopolymers (although this work on metakaolin based geopolymers). 

2. Line 277: "The research underscores the potential of foamed geopolymer coatings for effective 277 and economical surface protection". How surface protection was confirmed. The effect of geopolymer with its high alkalinity on steel was not investigated.

3. Line 18, line 275: "thermal conductivity of 0.166 W/m·K" In Table 2, it is 0.164.

4. Table 3 demonstrates that the present work is not novel. How can the authors demonstrate the novelty of this work.

5. line 171: "the foam 171 geopolymer exhibits compressive strength and bending strength values lower than 10.85 and 13.5, respectively." How the lowering of compressive strength goes with using on steel?

6. Section 3.2. and Figure 7. The results is Figure 7 is very interesting and they represent the novelty of this work. 

Author Response

Reviewer #1: The article under the title: “Geopolymer Composites: Manufacturing of sandwich steel and geopolymer structures with spray technology without Formwork” is appropriate for Coatings Journal. The organization of the article is typical for the research article. Overall, the paper is well-prepared, but it requires some improvements:

Note: 1. In the introduction, the authors failed to integrate the aim of the present work: foaming, fire resistance, sprayed concrete, steel- 79 reinforced fly ash geopolymers (although this work on metakaolin based geopolymers).

Answer: The authors revised the manuscript following the suggestion of the reviewer (see lines 80-90 in the revised manuscript).

Note: 2. Line 277: "The research underscores the potential of foamed geopolymer coatings for effective 277 and economical surface protection". How surface protection was confirmed. The effect of geopolymer with its high alkalinity on steel was not investigated.

Answer: The text was revised following the suggestion of the reviewer (see lines 272-282 in the revised manuscript).

Note: Line 18, line 275: "thermal conductivity of 0.166 W/m·K" In Table 2, it is 0.164.

Answer: The text was revised.

Note: 4. Table 3 demonstrates that the present work is not novel. How can the authors demonstrate the novelty of this work.

Answer: Table 3 was revised with the new literature in the manuscript (see lines 201-202).

Note: 5. line 171: "the foam 171 geopolymer exhibits compressive strength and bending strength values lower than 10.85 and 13.5, respectively." How the lowering of compressive strength goes with using on steel?

Answer: Geopolymer coatings, distinguished by their exceptional thermal stability, fire resistance, and chemical resilience, represent a viable avenue for bolstering the safeguarding of structures against the perils of fire-induced damage within the realm of construction. Therefore, it only has a shielding effect and does not bear force.

Note: 6 Section 3.2. and Figure 7. The results is Figure 7 is very interesting and they represent the novelty of this work.

Answer: yes.

Yours sincerely,

Van Su Le

Corresponding author

Reviewer 2 Report

The authors present a study on foam and non-foam geopolymers for fire protection. This itself is of interest, however, I have major concerns about this manuscript.

In my opinion, the study shows too little experimental work to make it of significance to publish. This is emphasized by the fact that the authors have copy-pasted Table 2 and Figures 4, 5, and 6 from other references rather than obtaining these data in the current manuscript. However, the authors present the figures as if they were their own. Other authors data should not be presented as your own results. As an example, the legends in Figure 4 states "this work", but it is actually the work in Ref 31, and the references and "this work" found in Table 2 are actually from Ref. 7. 

The text contains many errors in syntax, as well as capital or non-capital letters. Generally, the text should be more scientific.

Author Response

Reviewer #2: The article under the title: “Geopolymer Composites: Manufacturing of sandwich steel and geopolymer structures with spray technology without Formwork” is appropriate for Coatings Journal. The organization of the article is typical for the research article. Overall, the paper is well-prepared, but it requires some improvements:

Note: 1. The authors present a study on foam and non-foam geopolymers for fire protection. This itself is of interest, however, I have major concerns about this manuscript.

In my opinion, the study shows too little experimental work to make it of significance to publish. This is emphasized by the fact that the authors have copy-pasted Table 2 and Figures 4, 5, and 6 from other references rather than obtaining these data in the current manuscript. However, the authors present the figures as if they were their own. Other authors data should not be presented as your own results. As an example, the legends in Figure 4 states "this work", but it is actually the work in Ref 31, and the references and "this work" found in Table 2 are actually from Ref. 7.

Answer: The authors revised the manuscript following the suggestion of the reviewer

Yours sincerely,

Van Su Le

Corresponding author

Reviewer 3 Report

This paper shows an investigation on the Geopolymer Composites: Manufacturing of sandwich steel and geopolymer structures with spray technology without Formwork. Generally, this topic is interesting, and this paper can be considered after the following being addressed.

(1) The background of this study should be first given at the begin of the abstract section.

(2) In the introduction section, the author should give a general review on the properties of geopolymer materials. The following two references may be helpful. (a) Development of sustainable geopolymer materials made with ground geopolymer waste powder as renewable binder up to 100% (b) Microstructure and macro properties of sustainable alkali-activated fly ash mortar with various construction waste fines as binder replacement up to 100%.

(3) If possible, the XRD pattern and particle size of various binders should be given in the 2.1 Materials section.

(4) Figure 7 not clear enough, which should be replaced with clear one.

(5) The length of conclusion is a little short, and more findings can be given in conclusion section.

Moderate editing of English language required

Author Response

Reviewer #3: The article under the title: “Geopolymer Composites: Manufacturing of sandwich steel and geopolymer structures with spray technology without Formwork” is appropriate for Coatings Journal. The organization of the article is typical for the research article. Overall, the paper is well-prepared, but it requires some improvements:

Note: 1. The background of this study should be first given at the begin of the abstract section.

Answer: The text was revised following the suggestion of the reviewer (see lines 25-33 in the revised manuscript).

Note: 2. In the introduction section, the author should give a general review on the properties of geopolymer materials. The following two references may be helpful. (a) Development of sustainable geopolymer materials made with ground geopolymer waste powder as renewable binder up to 100% (b) Microstructure and macro properties of sustainable alkali-activated fly ash mortar with various construction waste fines as binder replacement up to 100%.

Answer: The authors added the new literature in the manuscript (see lines 49-50 in the revised manuscript).

Note: 3 If possible, the XRD pattern and particle size of various binders should be given in the 2.1 Materials section.

Answer: Unfortunately, we do not do this analysis.

Note: 4. Figure 7 not clear enough, which should be replaced with clear one.

Answer: Complete

Note: 5. The length of conclusion is a little short, and more findings can be given in conclusion section.

Answer: The text was revised

Yours sincerely,

Van Su Le

Corresponding author

Reviewer 4 Report

The authors examined the fire resistance of geopolymer composites, which is an interesting study. However, there are some issues in the manuscript that need to be revised by the authors.

Page 1 line 25-39, too many generalized features of geopolymers are introduced here, and the authors should simplify this.

2、Page 3 line 107-115, "mixed at high speed" what kind of mixing speed?

3. Page 7 line 196, Table 3 has an editorial error. And authors should know that their work is not just copying pictures from other people's articles.

The reviewer had no comments on this.

Author Response

Reviewer #4: The article under the title: “Geopolymer Composites: Manufacturing of sandwich steel and geopolymer structures with spray technology without Formwork” is appropriate for Coatings Journal. The organization of the article is typical for the research article. Overall, the paper is well-prepared, but it requires some improvements:

Note: 1. Page 1 line 25-39, too many generalized features of geopolymers are introduced here, and the authors should simplify this.

Answer: The text was revised following the suggestion of the reviewer (see lines 25-33 in the revised manuscript).

Note: 2. Page 3 line 107-115, "mixed at high speed" what kind of mixing speed?

Answer: That's the speed of a hand mixer.

Note: Page 7 line 196, Table 3 has an editorial error. And authors should know that their work is not just copying pictures from other people's articles.

Answer: Table 3 was revised with the new literature in the manuscript (see lines 201-202).

Yours sincerely,

Van Su Le

Corresponding author

Round 2

Reviewer 1 Report

The authors did not respond for my comments. The authors write: The text was revised and when considering the test I did not find the answer to the comment.

Reviewer 2 Report

The authors did reproduce some of the figures and tables they had copied from literature. However, they did not provide any additional experimental data which was my key concern in order to make this of significance to publish as a research paper.