Research of Strength, Frost Resistance, Abrasion Resistance and Shrinkage of Steel Fiber Concrete for Rigid Highways and Airfields Pavement Repair

Round 1

Reviewer 1 Report

Dear authors,

Find attached my comments in your manuscript. Besides the comments of the manuscript:

1) Replace the decimal separator by a dot. Note: the graphs are ok, the text no.

2) Explain how did you introduce the the hardening accelerator and the fibers in the composition: was they by mass? was they by volume? Of what? I cannot understand how did you reach the mix contents!

3) The issue of the water has to be clarified! How did you change the water content? Was it based in what? Then you presented a model - based in what? What errors? What significance? What statistic analysis?

4) Describe the  number of specimens tested by test! What are the results the average? What are the standard deviations?

5) You need to present statistical tests for the response models - Are the models significant? Moreover, the central composition - did you repeat it? What are the normal deviation?

The paper is good, is well written but the experimental research needs to be improved, especially the results and analysis of results.

Bes regards

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Authors addressed several of the reviewer's comments and feedback and manuscript is acceptable in it's current form.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript focused on the influence of the hardening accelerator and fiber dosages on the strength, frost resistance, wear resistance and shrinkage of repair steel-fiber reinforced concrete for rigid pavements. Though many experimental results are presented, in my opinion, the quality of the manuscript needs to be further improved.

 

1. In the abstract, line 22, is it 1 and 2% or 1.2% of the cement content? Please correct it. The abstract needs to be written clearly by highlighting the methodology, mixes, and key findings.
2. In the introduction, as the author mentioned in line 94, “A large amount of experimental data [24, 25] confirms…..”, so please clearly highlight the objectives of this paper and mention the difference between the present study and previously published results in the literature.
3. Add all the standards (e.g., ASTM, BS EN…) to the list of references and cite them accordingly.
4. For better understanding the reader, all commas may replace by points for the numeric number.
5. The purpose of Table 1 is not clear in the body text; please add more comments to understand the reader better. However, the methodology is not discussed in detail. Indeed, many analysis and test methods need to be explained in detail.
6. Line 128, the fiber length compared to the diameter is relatively high; please clarify it.
7. Please mention the test method and standard for the workability test.
8. Introducing some images after the flexural test, the discussion on the failure mode, and image analysis after the frost resistance tests could be interesting.
9. There are many descriptions of experimental phenomena. Indeed, an in-depth explanation of the experimental results of the study is needed.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors improved their paper. The manuscript can be published in the present form.

Reviewer 3 Report

Thanks to the author for considering the comments. The authors significantly improved the revised manuscript by addressing the comments appropriately. Therefore, the paper can be accepted for publication.

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

The comments were corrected. Thanks.

Reviewer 2 Report

The paper aims at evaluating the effects of the use of steel fibers and a hardening accelerator additive on compressive strength, flexural strength, frost resistance, abrasion resistance and shrinkage of concretes for the repair of rigid highways and air- fields pavement. The authors present a two-factor investigation, which takes into account three different amounts of fibers and hardening accelerator. The topic of the paper is interesting, but the design of the experimental campaign is questionable.

• The amount of water was varied to obtain S2 Slump. However, S2 Slump defines a range from 50 to 90 mm that is wide; hence, the amount of water proposed by the authors cannot be precise. I think the authors should provide for each mix considered different slump results (in mm) related to different W/C, so as to demonstrate more precisely the W/C necessary to maintain the same exact workability.
• Moreover, by changing the amount of water, the W/C ratio varies and this affects the performance of concrete, especially in terms of compressive strength and flexural strength. Hence, the expressions proposed by the Authors for flexural strength (Eq. 2-3) and compressive strength (Eq. 4-5) that account for the effects of steel fibers and the hardening accelerator additive would be different if W/C ratio was kept the same for all the mixes. I think the authors should have kept the same W/C ratio for all the mixes and varied the amount of plasticizer to keep the same workability.

Reviewer 3 Report

While this is an interesting study, it is of limited extend based on a relatively small experimental case study. A lot has been done over the years in assessing the influence of hardening admixtures and steel anchor fibers on concrete properties and pavements. Thus, the fact that this study was based primarily on one concrete mixture (i.e., 9 batches of the same mixture keeping cement constant and very minor variations in coarse and fine aggregate), Table 2, further indicates the limited value and transferability of the findings elsewhere. Thus, it’s contribution and value to the state of knowledge in concrete and pavement repairs is limited, since it simply examines the influence of only two of the many factors affecting concrete properties and performance.

The manuscript also fails to relate to the literature and knowledge from the extensive past studies examining hardening accelerator and steel fibers in concrete properties and pavements. Such findings are barely discussed, and yet not describe what was learned and what were the specific obstacles that have been encountered in the past, that then this study is able to address. This also implies that the authors fail to “build on” past knowledge in this area for developing their own study.

Furthermore, the authors fail to discuss how their findings relate to an extensive set of studies over the years in this area, how the findings will affect and benefit repairs, how the data are transferable elsewhere, and what needs to be further investigated.

Other issues in the manuscript include:

• On page 2, lines 62 to 64, the authors refer to “Research is based on a novel procedure based on a definition of the hardening accelerator effect and steel fiber on strength characteristics, frost resistance, abrasion resistance and shrinkage during hardening of repair steel-fiber reinforced concrete for rigid road and airfield pavements,” but there is nothing novel about this study since such effects have been examined in the past.

 

• Figure 2 is mislabeled and not represents what it actually shows.

 

• Some table and figure titles are too cumbersome: Table 3, and should be shortened properly referring to the reference number the authors want to refer to; Figure 6, need a label or ‘Note” to better indicate all the info the authors try to include in the Figure title.

 

• Modeling is limited, since equations are primarily based on simple regressions based on the limited data and variables consider in this study

 

• The manuscript Abstract and Conclusions sections are very limited in value and brief, and thus fail to address important issues:

 

• Most of the abstract repeats the specific findings included in the manuscript missing the big picture and impact of this study (i.e, without making the case of why this study was important, how it contributed to the extensive studies in this area, and how the findings are transferable elsewhere).
• Similarly, the Conclusions section is very poor and limited, and without explaining how such findings will impact concrete highway and airfield repairs, how the findings are transferable elsewhere, and what needs to be examined further.