Mechanical Properties and Damage Characteristics of Coal-Based Solid Waste Paste Filling Materials with Different Moisture Content
Round 1
Reviewer 1 Report
This article is so innovative that I was attracted by its novelty when I first read it. Coal - based solid waste preparation paste backfill has been called for by industry experts in recent years. The paper considers the weakening effect of water in goaf on the strength of coal-based solid waste paste filling material after filling into goaf, as well as its damage and failure characteristics. Based on the novelty of this paper, I propose the following comments and suggestions for the article, and invite the author to consider revising the article before publication.
1. The author should compare the format of the journal and adjust the format of the article, including the title, citations and references.
2. "Fig. x" should be changed to "Figure x" in the article.
3. It is unnecessary to introduce the sources of coal gangue and fly ash in lines 99 and 106, because these are obvious. Only two sources of solid waste in line 90 need to be retained.
4. Change "formula" to "equation" in lines 131 and 206 of the article.
5. In the articles I have read, such as the reference (10-12), Feng Guorui et al. used the same ratio of filling materials as that in this paper, but their strength reached about 7Mpa, while the maximum strength in this paper was only 3Mpa. Please explain the reason.
6. I think the paper has a good influence mechanism on the strength of coal-based solid waste paste filling materials with different moisture content. I hope the author can continue to carry out in-depth research from three aspects: structural effect, physical effect and chemical effect.
Author Response
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Author Response File: 
Author Response.docx
Reviewer 2 Report
In this paper, the strength and damage of coal-based solid waste filling materials with different water content are analyzed. The writing is standardized, the thinking is clear. But at the same time, I also found some problems in the paper. I hope the author can revise it well to improve the quality of the paper.
（1）The last paragraph of the introduction describes that "there are relatively few studies on the influence of humidity change on the performance of filling ". I think this statement is unreasonable, and suggest the author be more rigorous.
（2）The quality of Figure 3 is too low. It is recommended to modify it.
（3）The fitting formula in Figure 4 is characterized by a quadratic function. It is suggested to supplement the literature.
（4）Small icons need to be added to the 4 subgraphs in Figure 6.
（5）The author thinks that the constitutive model is more suitable for water filled objects through tests. Please give further explanation?
（6）Please check the language typing and grammatical errors throughout the manuscript.
Author Response
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Reviewer 3 Report
The preparation of filling materials from coal-based solid waste itself is a very innovative research direction. Based on previous studies, the author considers the influence law of water content on the strength of filling body based on the water richness of goaf. On the whole, the research of the article is quite outstanding. However, before the article is published, it is hoped that the author can make the following improvements:
1. In this paper, four different water states are prepared: dry, natural, semi saturated and saturated. What is the main basis for the preparation of these four water states?
2. The acoustic emission equipment is included in Figure 2, but it is not included in the subsequent instrument introduction. The author needs to make a detailed introduction to the instrument used.
3. We have carefully read the reference (10-12). The material ratio used in the reference is the same as that in this study, but the natural strength is more than 2 times that in this study. We hope the author can explain this.
4. The description of "Fig 4" in line 259 is incorrect. It should be changed to" Figure 5". Please check it carefully.
5. What does the author mainly mean in lines 259-262? It's a brief description, but it doesn't go far enough.
6. In this study, the influences of different water-bearing states on backfill strength were discussed from three perspectives: structural effect, physical effect and chemical effect, which is a good idea. We hope to see in-depth research on this part in the author's subsequent articles.
7. Some more related references can be reviewed to impove the paper.
Author Response
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Reviewer 4 Report
The manuscript "Mechanical properties and damage characteristics of coal-based solid waste paste filling materials with different water content" by Meng Wang, Xiang He and Ke Yang was submitted for peer review.
I read the submitted manuscript with great interest. The authors turned to a very urgent problem: creation of backfill based on coal mining waste and study of strength characteristics after hardening. The use of coal mining waste in backfill material reduces the impact on the environment by involving industrial waste into a closed production cycle. The authors propose to use industrial waste in the material composition. The authors propose to change the water-to-solid ratio in order to study the material properties.
The manuscript has significant flaws that need to be corrected. Correction of the shortcomings listed below must be done to improve the quality of the manuscript, enhance the ease of perception of the presented material and increase the interest of a readers.
1.) From my point of view, there are very few keywords. In addition, the keywords should be more direct and related to the manuscript content. Keywords enable the reader to quickly search for the necessary material and enable the author to popularize their research and increase interest and citations. But if this number of keywords satisfies the requirement of the journal, this comment is advisory.
2.) The abstract is not quite formed correctly. It is very blurry and framed incorrectly. It seems that the authors have taken certain phrases from the text and thus formed the abstract. The abstract should clearly indicate the purpose of the study, its importance for society (i.e. to characterize the problem), identify the methods and materials of the study, and the conclusions should be clearly and briefly formulated. There is no "starting point" in the abstract, that is, information about previous studies (one sentence is enough). From my point of view, in the abstract, such information begins with the statement: "Previously conducted studies have established that ...".
2.1) It is desirable to avoid narrative text in the abstract.
2.2) Try to use words and phrases: an analysis has been carried out; studied; developed; proposed; established and so on. It is advisable to start sentences in the abstract with these words and phrases.
2.3) At the end of the abstract, it is necessary to indicate the final result obtained by the authors, for example: A model has been developed that allows ...; A dependence has been established which is...; A pattern has been revealed...; An efficient system (technology) has been proposed, and so on.
The abstract should be revised.
3.) The manuscript has a weak list of references (29 references in total). There is no comprehensive coverage of research in terms of geography of citations. There are no references to international experience in the field, especially to the work of East European, Ukrainian or Russian scientists. The list of references is intended to demonstrate the depth of the authors' study, the relevance of the material and interest of their research.
3.1.) The depth of study is demonstrated with the number of references – is on the verge of sufficiency.
3.2.) Relevance – with the availability of research in recent years – is enough.
3.3.) Interest – with the availability of research by scientists from different countries - is not enough (practically absent).
Since you are publishing your manuscript in an international publication, it is necessary to demonstrate the international relevance and interest of this issue. This can be done by analyzing the studies of scientists from different countries. It is imperative to supplement the list of references with studies of scientists from different countries over the past 3-5 years to show geographical (general/global) interest and relevance.
The List of References needs to be completed.
4.) In the introduction when analyzing previous studies, the authors make inaccuracies or provide information that overloads the text and often their claims are not accompanied with evidence. It is important for readers to know the essence (main idea) of the research you are referring to when analyzing previous work. In the introduction, it is necessary to analyze the previously completed work and note what has been done, what are the shortcomings, and what has been done incorrectly. Also, there is no geographical coverage in the previous studies analysis. Such shortcomings are present throughout the introduction. Authors need to revise the introduction, adjust and supplement their statements with evidence.
5.) From my point of view, the authors abuse the names of scientists when mentioning the study. A reference [1] is sufficient. If the reader is interested in the name of the researcher, then it is easy to refer to the references list. It is important for the reader to know the essence (main idea) of the disclosed issue, not the name of the researcher.
6.) At the end of the introduction, a brief conclusion of the analytical study of earlier papers is formulated very poorly. The authors did not summarize their analysis and did not identify unresolved issues. This conclusion should make it possible to characterize the actual question posed, the purpose of the study and the tasks to be solved to achieve this goal. For example: Analyzing the above, it can be noted that ... is a very topical issue. Therefore, the purpose of this study is ... and to achieve this, it is necessary to solve the following tasks: 1); 2); ... Such a conclusion allows the authors to correctly formulate the conclusions and the reader to understand the vector of the study. It needs to be improved.
7.) Considering the comments (3) and (4), I would like to note that the authors have very poorly disclosed the main subject of the study. Indeed, humidity in mining plants adversely affects the curing rate and ultimate strength of the backfill in underground conditions. The impact of waste dumps on the environment is great, so the issues of reducing this impact are very relevant and scientists around the world are trying to minimise it. In recent years, a lot of work has been carried out on the study of a material created on the basis of enrichment tailings with the aim of their subsequent use in a closed, waste-free (low-waste) production or for products intended for civil engineering.
For example,
7.1) Kongar-Syuryun, Ch.; Aleksakhin, A.; Khayrutdinov, A.; Tyulyaeva, Y. Research of rheological characteristics of the mixture as a way to create a new backfill material with specified characteristics. Materials Today: Proceedings 2021, 38, 2052-2054. https://doi.org/10.1016/j.matpr.2020.10.139.
In this study, the authors study a composite based on waste from the processing of water-soluble ores. Particular attention is paid to the study of the composite transportability while maintaining the specified strength characteristics. The unifying factor of this paper with the manuscript submitted for peer review is the study of the water-to-solid ratio, which has a significant impact on both transportability and final strength.
7.2) Ermolovich, E.A.; Ivannikov, A.L.; Khayrutdinov, M.M.; Kongar-Syuryun, C.B.; Tyulyaeva, Y.S. Creation of a Nanomodified Backfill Based on the Waste from Enrichment of Water-Soluble Ores. Materials 2022, 15(10), 3689. https://doi.org/10.3390/ma15103689.
This work is similar in terms of goals, objectives and research methods to the manuscript submitted for peer review. The authors study a composite based on waste from the processing of water-soluble ores. To increase the strength characteristics of the created composite, fullerene-astarlene is used as a nanomodified additive. From my point of view, this work should be used in the analysis of previously performed studies, since it uses the methods of mechanical, microstructural, X-ray phase and petrographic analyzes to confirm arguments. This study is suitable for the authors to prove the statement that microstructural analysis allows to prove new formations and the presence of strong bonds in the new material.
7.3) Rybak, J.; Adigamov, A.; Kongar-Syuryun, C.; Khayrutdinov, M.; Tyulyaeva, Y. Renewable-Resource Technologies in Mining and Metallurgical Enterprises Providing Environmental Safety. Minerals 2021, 11(10), 1145. https://doi.org/10.3390/min11101145.
This work is devoted to the study of a composite based on industrial waste from mining and metallurgical industries. A feature of this study is an attempt to additionally extract a valuable component (to zero level) left in the waste before their subsequent use in mining or civil production. From my point of view, this study is suitable for analysis.
7.4) Kongar-Syuryun, Ch.; Tyulyaeva, Y.; Khayrutdinov, A.M.; Kowalik, T. Industrial waste in concrete mixtures for construction of underground structures and minerals extraction. IOP Conference Series: Materials Science and Engineering 2020, 869(3), 032004. https://doi.org/10.1088/1757-899X/869/3/032004.
In this study, the authors propose to apply the activation treatment of tailings prior to their mixing in the composite to improve the strength characteristics. Activation treatment of the components or the addition of some kind of activating additive is one of the ways to improve the quality of the created composite. From my point of view, this article is suitable for authors in the analysis of studies to demonstrate various options for controlling the characteristics of the created composite.
If the authors become familiar with the works presented in (7.1), (7.2), (7.3), (7.4) they will be able to properly form the introduction, enrich their manuscript with international research by scientists from Poland, Czech Republic, Slovenia, Slovakia, Russia, Germany and demonstrate the depth of their material, as well as eliminate the remarks (3) and (4).
8) Of particular interest to me, and I think readers as well, is SEM and XRD analysis of coal gangue and fly ash. From my point of view, it is necessary to indicate the research instruments (type/model) and the database that was used in XRD analysis of coal gangue and fly ash. Readers need to know all this so that they can repeat the experiment.
9.) It is necessary to indicate:
9.1) the brand of Portland cement and preferably the manufacturer of the cement used by the authors;
9.2) how many samples were prepared;
9.3) how was the convergence of the results achieved;
9.4) how was the homogenization (mixing) carried out; what is the component mixing tool; what is the mixing velocity and time;
9.5.) what is the sequence of filling of the components;
9.6) it is also not clear how the homogeneity of the composition (thoroughness of mixing) was achieved, provided that the amount of some components in the composite is minimal;
9.7) what equipment was used to study samples for uniaxial compression;
9.8) The authors test samples at the age of 28 days. From my point of view, the reason for abandoning the standard methodology for testing the strength at 7, 28 and 60 days should be clarified.
To eliminate remarks (8) and (9), I would recommend reading the work (7.2). The recommended paper is similar to the one submitted for peer review and describes the methodology in sufficient detail.
10.) From my point of view, the Conclusion is not quite correctly formulated. Paragraph IV of the Conclusion should be taken to the Discussion, but this is only a recommendation.
Summary: The manuscript is not a finished research work. The corrections are needed. The chosen research topic is relevant. From my point of view, the authors failed to present their research correctly and clearly, which reduced its value and worsened the ease of perception of the material presented. From my point of view, the manuscript cannot be published in the open press without correction in accordance with my suggestions.
Author Response
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Author Response File: Author Response.docx
Round 2
Reviewer 4 Report
The authors practically did not make corrections in accordance with my recommendations and did not comment on these points in the cover letter. There is only a complete answer to point 1 and a partial answer to point 2. I recommend that the authors revise the article in accordance with the first review.
Author Response
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Author Response File: Author Response.docx
Round 3
Reviewer 4 Report
The manuscript "Mechanical properties and damage characteristics of coal-based solid waste paste filling materials with different water content" by Meng Wang, Xiang He and Ke Yang was submitted for second review.
As can be seen from the submitted manuscript and the explanatory note to the review, the authors did a lot of work to make changes in accordance with the comments.
The revised manuscript is a completed scientific study on a highly relevant topic: creation of backfill based on coal mining waste and study of strength characteristics after hardening. The revised version of the manuscript, in my opinion, fully satisfies the requirements of a scientific article and can be published in the open press.
