Research on Layered Steel Fiber Reinforced Concrete Mix Ratio Design Based on Orthogonal Test

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript presents a comprehensive study on the mix ratio design of Layered Steel Fiber Reinforced Concrete (LSFRC) using orthogonal experiments to evaluate the mechanical properties. The work is well-structured and provides valuable insights into the optimal mix ratios for achieving desired mechanical properties. However, several areas require clarification and enhancement to improve the overall quality and readability of the paper.

1. Introduction: On page 1, clarify what specific “problems in application” the authors are referring to regarding steel fiber reinforced concrete. Provide concrete examples.

2. Introduction: “Currently, most research on LSRFC is focused on the structural level, and there is relatively little research on mix proportion design for LSFRC concrete materials.” That is not quite sure about this statement. Clearly state the novelty of this research compared to previous research. The reviewer recommended that rather than just listing previous studies, synthesize what the key findings have been regarding mix design, and identify specific gaps or limitations. For example, "While previous studies have shown the effectiveness of LSFRC at a structural level, there is still a need to optimize the mix proportions to balance mechanical properties and cost.”

3. Add more recent references to support the relevance of the study on the improvement of flexural strength of the concrete pavement: “Natural Rubber Latex–Modified Concrete Pavements: Evaluation and Design Approach. Journal of Materials in Civil Engineering, 34(9), 04022215.”

4. Materials and Methods: In section 2.3 on specimen fabrication and testing, add details on the mixing procedure (e.g. order of adding constituents, mixing time) and how the layered structure was formed (e.g. were the plain and fiber concrete layers cast separately? vibration used?).

5. Experimental Design: In Table 2, clarify the basis for the factor levels selected. What properties of the sand led to choosing 35/40/45%? Why 0/10/20% fly ash replacement?

6. Explain why non-standard specimen dimensions were used for the tests and how this might affect the results compared to standard dimensions.

7. Provide more detail on the preparation and curing process of the concrete specimens to ensure reproducibility. And clearly state the ages of testing samples.

8. From Table 5, the reason why should be provided rather than just reported the observed values.

9. Tables 6 and 7, what age of the test samples? Also clearly state for other tests.

10. Optimal Mix Design: Explain step-by-step how the optimal mix in Table 13 was determined. What criteria and weightings were used to select the factor levels, given that the individual optimal levels for each property differ somewhat?

11. Please link the optimal mix design to the objective of this study. Discuss any practical considerations that influenced the optimal mix, e.g., cost, workability, and local material availability.

12. Lines 106-108: SEM analysis was conducted and compared the different curing ages of samples. However, there is no show the strength development in physical tests. The authors should provide more information. For example, In the Results section, before presenting the SEM images, show the compressive, flexural, and split tensile strength results as a function of curing age. Then, when presenting the SEM results, refer back to the strength data.

13. In the 1st conclusion, provide the specific compressive, flexural and split tensile strength ranges that correspond to the stated 5%, 5%, 10% changes with fiber content.

 

14. In the 3rd conclusion, clarify what is meant by "prepared and maintained in advance" and how this relates to the aging results. Provide a more direct comparison of the property changes with age for the LSFRC versus a control concrete.

Comments on the Quality of English Language

Moderate editing of English language required

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The paper "Research on LSFRC Mix Ratio Design Based on Orthogonal Test" is interesting and provides insight into the concrete technology of steel fiber reinforced concretes. The methodology and analysis of results is very well prepared. The paper is also well written. There are however a few issues I would like Authors to elaborate upon:

1. Authors say that there is very little known about the mix design for steel fiber reinforced concrete. While the topic requires further research, a lot was done in this area, and it might be beneficial to discuss the findings in the introduction, and to better convey the novelty of the paper. 

2. Why those 9 sample compositions were chosen (table 3)? Several compositions are missing, such as A2B2C2D2 or A3B3C3D3.  

3. Why non-standard sizes of the specimen were chosen for strength testing? 

4. There is no description of the standard for slump flow; how many samples were tested for each result? 

5. What was set as the 'optimal' result for the research? in chapter 4, one mix is being tested, and the strength difference between the sample with the fibres and without may not be significant (depending on what were the error bars), and the description provides only the general comparison of the samples, there is however no conclusion or remark on the validity or wheter the set expectations were met. I believe that the paper would benefit from deeper explanation of what was the aim and bar set for the concrete properties. 

Minor comments: 

 - There is a mistake in the word 'introduction'. 

- The materials section would benefit from the grain size distribution, if such test was conducted, 

Author Response

Please refer to the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have sufficiently responded to the reviewer's comment and revised the manuscript correspondingly.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have made sufficient changes to the paper which improved the paper.