Mechanical Properties and Thermal Conductivity of Fly Ash-Based Geopolymer Foams with Polypropylene Fibers

Round 1

Reviewer 1 Report

The current study looks into the mechanical and thermal performance of geopolymer foam material for the use in fire protection applications. For this the authors measure the compress and tensile strength. The authors also evaluate the thermal conductivity within a certain range of temperature. The authors found that the geopolymer have good mechanical properties when adding fibres to it and low thermal conductivity was found.

The abstract needs more work, first of all the conclusions are very generic, what is meant by good? Please try to use a more scientific and accurate way to describe your findings, for example good relative to what.

Please consider reviewing the abstract and highlight the novelty, major findings and conclusions.

Also in the title the authors did not give an indication that this geopolymer will be reinforced with fibres therefore, they are encourage to use a title that better reflects the work done here.

Introduction is very short and can be expanded, please summarise and discuss on previous studies which did similar work to yours and explain what they did, what were their main findings and how does your current study brings new knowledge and difference to the field.

Then after you add this additional literature review, please answer the following question: What is the research gap did you find from the previous researchers in your field? Mention it properly. It will improve the strength of the article.

Line 73, 75, 97, 102, 121, 131, 151, 158, 166, 182, 195, 212, 218 please check the reference issue?

Table 2 can the authors please explain why they choose those certain mixtures for the current study? Are they according to certain standards or recommended by industry or past literature. Please elaborate further and support with references

The quality of figure 4 can be improved

I think the main critical work in this manuscript is the comparison of geopolymers with and without fibres please highlight this properly in the abstract, introduction and discussion.

Line 167 “the compressive strength does not exceed 10 MPa.” What does that mean, is it low or high, in comparison to other similar materials ..etc what does that mean in terms of its performance? please discuss further and support with references

Line 171 “indicated good mechanical properties” I am still not clear of what is meant by good mechanical properties? What is the bench mark used here to say that they have good or bad properties? This is very generic comment and does not have any meaningful value.

Figures 5 and 6 can be combined in one figure

Line 184 “that it has brittle properties compared with the others.” This is an important findings but it is not clear how did the authors conclude this, how did you decide that this material is more brittle? According to what? A standard, a past study similar to this work, please provide more critical discussion and use scientific explanation to discuss your results and findings.

The authors only say better, smaller or larger, however there is no critical discussion of their results. This must be improved everywhere the authors make a conclusion or report a finding from their results.

Line 223-224 “On the other hand, the thermal conductivity decreases when 0.50 % of the fiber is added to the foamed geopolymer” why? Please explain why this happen and support it with references.

The results are merely described and is limited to comparing the experimental observation. The authors are encouraged to include more  discussion and critically discuss the observations from this investigation with existing literature.

Author Response

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Author Response File: Author Response.doc

Reviewer 2 Report

1. Using "fire protection materials" in the title of the manuscript is not appropriate, because the authors only studied thermal conductivity, more test methods need to be used to quantify the efficiency as fire protection materials.
2. The abstract needs to be revised, too much background was described, what's the test methods used, and what's the main findings.
3. The authors could extend the introduction by reviewing more Geopolymer materials related references.
4. The reference of tables and figures in the text has format errors.
5. What's the humidity of the geopolymer curing condition?
6. Please rephrase the sentence in lines 136-139.
7. The title in line 194 is incorrect.
8. The sentence in lines 223-224 is incomplete?
9. Please refine the main findings in the conclusion section, not just repeat some test results analysis

Author Response

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Author Response File: Author Response.doc

Reviewer 3 Report

Major revision

The discussion of the results is very poor, the authors described what the graphs/tables show, without any interpretation or attempts to explain the obtained results. The authors compared their results to only 2-3 results from other studies, which also indicates little scientific significance.

The discussion of the results may be in a few words, if the authors did not present the same data as in the tables / figures. There is no scientific interpretation in the article.

Minor revision 

no superscripts on units

Lines: 73, 75, 97, 102, 120, 131 and others: "Error! Reference source not found" - remove

Figures are unreadable - improve quality

Table 1 - Self-Citation - have the Authors used the same data in another article?

Section 3.3. is twice and tthe table 3. have the same title as section 3.3. 

Author Response

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Author Response File: Author Response.doc

Round 2

Reviewer 1 Report

Figure 6 is not clear

also check other figures quality its very poor and not easily read

Author Response

Response to Reviewer 1 Comments

Point :  Figure 6 is not clear, also check other figures quality its very poor and not easily read.

Response : The authors change the quality of the figure 6 and the others.

Reviewer 2 Report

The revised manuscript is good.

Author Response

Response to Reviewer 2 Comments

Point : The revised manuscript is good

Response : Thank you. The authors changes again the quality of the figure.

Reviewer 3 Report

The authors put a lot of work into modifying the manuscript.

I propose to add paragraphs to sections: 3.2, 3.3 and 3.4 that will explain the observed situations and changes in properties.

I also propose to add information about the applicability of the developed material, taking into account the properties obtained. 

Author Response

Response to Reviewer 3 Comments

Point 1: I propose to add paragraphs to sections: 3.2, 3.3 and 3.4 that will explain the observed situations and changes in properties.

Response : The author added the observed situations to section 3.2 (in line 189-191 and in line 210-212), section 3.3 (in line 224-226), section 3.4 (in line 244-246)

Point 2: I also propose to add information about the applicability of the developed material, taking into account the properties obtained. 

Response : The authors still doing some lab work for the application of this material as coating insulation in precast hollow-core slabs.  The authors plan to submit this research result in the next journal.