Experimental Study on Flexural Fatigue Resistance of Recycled Fine Aggregate Concrete Incorporating Calcium Sulfate Whiskers

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript entitled "Study on Flexural Fatigue Resistance of Recycled Fine Aggregate Concrete by Calcium Sulfate Whiskers" discusses the research conclusions of previous scholars on the mechanical properties of recycled fine aggregate concrete based on the concept of green and sustainable development in the construction industry. The advantages and disadvantages of the mechanical properties of recycled fine aggregate concrete and ordinary concrete were compared from the perspective of strength and fatigue, and the flexural fatigue resistance test of recycled fine aggregate concrete by calcium sulfate whiskers was carried out. The logic of the writing is relatively smooth and relevant to the theme of the journal, and the following suggestions are for reference.

1、It is recommended to supplement the manuscript title as an experimental study;

2、Figures 2 and 4 seem to be duplicated;

3、Section 3.3 discusses that due to the non-homogeneity of the concrete itself, the flexural fatigue life fluctuates greatly. Is this due to the poor manufacturing process of the concrete used in the test? The strength of the concrete itself may be anisotropic, but the loading modes of different concrete test blocks in the test are the same, and it is difficult to explain the fluctuation of fatigue life by the non-homogeneity of the concrete material itself；

4、The difference between the S-N curves obtained by fitting the fatigue test data in Section 4.2 is not large, so how to explain the large difference in the fatigue life of the different concrete test blocks mentioned above from the S-N curves? The fatigue life under each stress level discussed in the manuscript is: C1RF>NC>C2RF>C0.5RF>C3RF>RF, but the fitting results in Figure 10 do not meet this conclusion. Please explain;

5、It is suggested that the author should simplify and improve the structure of the manuscript, such as the analysis of fatigue life at the end of equation (8), fatigue life decreasing with the increase of stress level, etc. Such conclusions do not need to be known through experimental analysis, which is lengthy and of little significance. Also, for example, in Figure 11 and Table 6, Figure 12 and Table 7, etc., there is no point in repeating them.

Comments on the Quality of English Language

The language of the manuscript is relatively fluent, but some of the sentences are too long, and it is recommended to simplify them appropriately.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Authors designed flexural fatigue cyclic loading tests under different stress levels with calcium sulfate whisker admixture as the main influencing factor. In order to analyze the fatigue life, the fatigue equation is established based on the three-parameter Weill distribution function theory. The important role of calcium sulfate whisker in concrete is explained scientifically.  In general this manuscript is interesting and brings novel results. However there are some shortcomings that need to be addressed.  

1、Please check the correctness of the equation, eq.(4). and The math notation is not correct (i.e., for the equations, the authors should use bold and lower case letter for vectors, and bold and capital letter for matrices).

2、The clarity of some figures in the manuscript needs to be improved. 

3、The introduction is too brief. Author can refer to the following literature to enrich the introduction.  doi: https://doi.org/10.1016/j.apm.2023.08.024

4、In figure 9. What is the meaning of n and S, please explain in detail.

5、The graphic illustration should be written in more detail. (For example, figure8-10)

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Authors will find the following comments also in the attached pdf file to be facilitated in revisions.

 

1. Clarify the acronym "SEM" as "Scanning Electron Microscope" if needed.
2. Balance the introduction by expanding the final part and possibly shortening the literature review.
3. Include more solid and recent citations related to sustainability in building materials.
• Meyer, C., 2009. The greening of the concrete industry. Cement and concrete composites, 31(8), pp.601-605.
• Ortiz, O., Castells, F. and Sonnemann, G., 2009. Sustainability in the construction industry: A review of recent developments based on LCA. Construction and building materials, 23(1), pp.28-39.
• Garito, M.A., Caforio, A., Falegnami, A., Tomassi, A. and Romano, E., 2023. Shape the EU future citizen. Environmental education on the European Green Deal. Energy Reports, 9, pp.340-354.
4. Avoid stating there are few research works on the use of recycled fine aggregates (RFA) and cite relevant studies.
• Kirthika, S.K. and Singh, S.K., 2020. Durability studies on recycled fine aggregate concrete. Construction and Building Materials, 250, p.118850.
5. Conduct more thorough research before making statements.
6. Ensure claims and phrases are supported by references.
7. Add quotes and references to support statements about the advantages of calcium sulfate whisker (CSW).
• Al-Dulaymi, S.A.A., Brown, T., Fellows, C., and Mahini, S.S., 2019. Prevention of Environmental Degradation of Epoxy Resins Modified with the Addition of Different Fillers.
8. Revise the statement regarding the "bending fatigue performance of recycled concrete" and cite relevant studies.
• Peng, Q., Wang, L., and Lu, Q., 2018. Influence of recycled coarse aggregate replacement percentage on fatigue performance of recycled aggregate concrete. Construction and Building Materials, 169, pp.347-353.
9. Improve the manuscript's English language and clarity.
10. Formulate shorter sentences for better readability and clarity.
11. Enlarge the images and improve image captions to provide precise descriptions

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Authors should consider a thorough review of their English language usage, both in terms of form and grammar, and may benefit from seeking assistance from the journal's language services or enlisting the help of a native speaker

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Accept.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,
I have carefully reviewed the latest version of your manuscript, following the first round of revisions. I am pleased to acknowledge that your efforts in addressing the suggestions and comments from the previous rounds have resulted in significant improvements to the overall quality of the manuscript.
Your meticulous attention to detail and commitment to incorporating the feedback is commendable. It is evident that you have thoughtfully considered each comment and implemented changes accordingly. The revisions have not only clarified several aspects of the paper but have also enhanced the overall coherence and readability.
Sincerely