Preparing Shotcrete Materials Applied to Roadways Using Gangue Solid Wastes: Influences of Mix Proportions of Materials on the Mechanical Properties

Round 1

Reviewer 1 Report

This paper is about using multiple components in a mixture design for concrete and including gangue as a replacement for traditional coarse aggregate.  Surely the subject is important for improving the adverse environmental impact of concrete.  However, the experimental methods used are not described well enough to determine whether this is a valid study.

From my reading of the manuscript, I can detect not information about the following critical aspects of mixture design:

(a) fine aggregate grading

(b) moisture content of the coarse and fine aggregate at the time of mixing relative to the saturated surface dry state.  This is absolutely critical in understanding the rheological properties, even slump

(c) structure of the gangue (i.e., surface texture, porosity, shape characteristics)

(d) the proportions of water used to prepare the mixtures.

(e) I can find no mention is made of any chemical admixtures used for water reduction or flow modification.

(f) There appears to be no information at all on the mixture preparation, including mixer geometry, speed, duration, etc.

According to the Aims and Scope statement of Applied Sciences, "The full experimental details must be provided so that the results can be reproduced."  This paper does not provide enough experimental details to even begin to know how to make one of the mixtures.  On this basis the paper should be rejected.

If the authors were to include the full details of the experimental methods, plus better characterization of their starting materials as described above, this paper could be suitable for publication in a journal that emphasizes very applied, practical topics, such as the Journal of Materials in Civil Engineering.

The paper was readable in most parts, but the English was tortured in certain parts.  Multiple sentences had problems with verb tense mixing, articles missing, awkward word or phrase choices, etc.  An English rewriting service will be needed if the authors are able to address the technical deficiencies of the paper.

Author Response

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Reviewer 2 Report

The authors present an interesting topic. The research is designed appropriately. However, the manuscript requires putting sections in the correct order and completing them. That is why I recommend a revision considering a few suggestions listed below.

1. In the introduction, it is worth showing the readers what roadway with shotcrete looks like.

2. The second section should be a description of the research material, and the third section should be a description of the research method. Currently, section 2 and subsection 2.2 have duplicate titles.

3. Subsection 2.1 is titled "Experimental materials and specimen preparation", and the authors include Figure 2, where they show the USC research, which they describe in subsection 2.2.2.

4. What rocks constituted gangue? Do the authors have sample photos of samples before crushing?

5. Line 122: It is good practice to show on a map the location of the mine from which the samples were taken.

6. Table 1: Why did the authors adopt such values? Were these values determined statistically?

7. The Conclusion section needs to include the most essential information: What was the purpose of this research? Were the presented results used to prepare the shotcrete material for underground roadways? What are the future research directions?

Additionally:

1. No reference to Figures 1 and 2 in the text.

2. Between each main section and subsection, there should be a short introduction describing what is included in a given section and subsection.

3. Line 9: Is the correspondence e-mail address correct?

4. Lines 83 and 86: There should be CO₂.

Minor editing of English language required.

Author Response

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Reviewer 3 Report

Dear Authors,

please find my comments:

1. The abstract of a scientific article should be short and highlight the main points. I doubt that the conclusions of a paper from Line 19 onwards need to be presented in this way.

2. It is not clear from the introduction what the novelty of the research is?

3. The authors may provide the cement and gangue chemical composition.

4. Table 1. The compositions of all the samples are different and the sum of the quantities exceeds 100%. The authors may provide the composition of the shotcrete - kg/m3

5. Which normative documents did the authors of the article use to guide their research (for example: specimens curing, slump test, compressive strength and so on) ? 

6. Experimental results: the authors do not present in this part the results obtained by other researchers for comparison with their own results.

I think the English is not correct, the article is difficult to read, and there are some incorrect terms.

Author Response

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Round 2

Reviewer 1 Report

The description of the experimental procedure has been improved somewhat.  The analysis of Results is superficial, however, basically at the level of concrete technology, not applied science, and there is no uncertainty analysis to shed light on the confidence in the results that are shown.

The English has improved somewhat in some places, but there are places in the newly added text where the English could be improved.

Author Response

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Reviewer 2 Report

I accept the manuscript for publication in its current form.

Minor editing of English language required. Especially in terms of punctuation.

Author Response

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Reviewer 3 Report

Dear Authors,

Table 1. are the units of Density measurement correct?

Section 2.2.2 Compressive Strength Test. I repeat my question again: which normative documents did the authors use to guide some properties like slump test, compressive strength? Because I don't think your answer is correct: The test was partially referenced to the regulation for testing the physical and mechanical properties of rock, etc. 

Author Response

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