This manuscript reports the study of compressive fracture characteristics of marble powder concrete, and GMM method is implemented to predict the fracture mode. The following are my comments:

1. Fig.3: add error bars

2. Fig 8&9: how many data points were used for each specimen?

3. Fig.11: add a scale bar

Author Response

Dear reviewer:

Thank you for your decision and constructive comments on my manuscript. Thanks very much for taking the time to review this manuscript. I appreciate all your comments and suggestions! We have carefully considered your suggestion and have made changes.

The part has been revised according to your comments. Revision notes are given as follows:

1、Fig.3: add error bars

We have redrawn the legend and added error bars (See attached manuscript). Thank you very much for your suggestions, thank you.

2、Fig 8&9: how many data points were used for each specimen?

Figure 8 shows a schematic diagram of the plain concrete cracks after they have been classified using the GMM classification method. There are 18928 data points in the figure, representing a microcrack. The marble powder substitution rate was increased from 5% to 25% with data points 20482, 21713, 19629, 17858, and 18003, respectively. Thank you.

3、Fig.11: add a scale bar

We have redrawn the legend to include a scale (See attached manuscript). Thank you.

Special thanks to you for your good comments.

Thanks!

Best regards!

Author Response File: Author Response.pdf

Reviewer 2 Report

In this work, uniaxial compression tests based on acoustic emission technology were carried out to study the rule and evolution process of marble powder concrete damage under compression.

I consider that the work needs major revisions to be accepted. I attach the suggestions.

Thank you

Comments for author File: Comments.pdf

Author Response

Dear reviewer:

The part has been revised according to your comments. Revision notes are given as follows:

1、In the introduction, attach information on the amount of marble waste that is generated, this would favor the scopus of the journal.

We have consulted the relevant information, and in the first paragraph(Red font“Marble is found in many parts of the world, such as China, Egypt, Turkey, and other countries. For example, the marble powder reserves in Hezhou, Guangxi alone amount to 2.6 billion cubic meters, with an annual output of 1 million tonnes of solid waste^[1]”) added the annual amount of marble waste produced. Thank you.

2、In materials and methods, add a comment about the chemical composition and the fineness of the marble.

We have added information on the chemical composition and fineness of the marble scrap powder used for testing in this paper at lines 84-87(The average particle size of marble powder was 16.87 μm, the average particle size of the surface area was 4.18 μm, the apparent density was 2.58 g·cm^-3, and the specific surface area was 388 m²·kg^-1. Its chemical composition is shown in Table 1, and its particle size distribution curve is shown in Figure 1.) and Table 1. thank you.

Table 1. Chemical composition of marble powder.

CaO	MgO	SiO₂	Al₂O₃	Na₂O	K₂O	Fe₂O₃	Loss
47.937	5.492	1.974	0.045	0.377	0.069	0.003	44.103

3、Check the dosage since it does not close the cubic meter of concrete.

We took your suggestion very seriously and carefully checked the marble powder concrete formula and carried out a field test, the results of which met the amount of concrete used for one cubic meter. To reduce the test error, we prepared 0.0513 cubic meters of concrete, i.e., theoretically, 15.2 standard cubic compressive test blocks could be poured, mixed well, and filled the molds, except for the material loss during the test, filling 15 test molds, the pictures of the field test are shown the end of manuscript. Thank you very much for your suggestions, which are extremely helpful to the rigor of this paper. Thank you.

4、In table 2, change the w/c ratio to the w/cm ratio (water/cement material). In lines 130-131 add some reference that justifies the following sentence: “It is speculated that marble powder may delay the early hydration reaction, and the influence will weaken in the later hydration period”.

We have amended w/c to w/cm. Thank you very much for your suggestion.

We re-reviewed the relevant literature in “Qiu Ronglin. Experimental study on slag from furnace bottom and marble powder as mixed mineral admixtures [J]. Fujian Building Materials, 2016 (02): 12-14. (in Chinese)”, but since there is no clear data to support the result, we deleted the statement and rewrote the part to ensure the rigor of this paper, and introduced previous research results to justify it(Lines 132-141 “According to the literature^[15], the influence of marble powder on the cement hydration process is weak, and the reduction of MPC strength is mainly attributed to the reduction of cement content in the concrete mixture. At the same time, it can be found that MPC has the highest strength loss rate in the early stage of curing and then decreases with the extension of curing time. The decline is particularly significant when the substitution percentage is high. When the marble powder substitution percentage increased from 5% to 25%, the strength loss rate from 3d to 28d decreased by 3.1%, 6.9%, 8.6%, 11.6%, and 12.1%, respectively, so the strength growth of MPC was more dependent on the curing time. From the above test results, the effect of marble powder on the strength of concrete is small when the substitution percentage is less than 15%”). Thank you.

5、In line 145 change in”homogeneous material to heterogeneous material”.

We have made the changes here and checked the full text. Thank you.

6、Add some measure to the SEM that justifies what is stated in lines (262 to 273)

We have added some SEM measures to justify the results (lines 281-285). “To ensure the simultaneity of the test results, the sample was taken from a fragment of the mortar mixture produced during the compressive strength test, approximately 5mm in diameter, which was glued to the test rig with conductive glue, vacuumed and sprayed with gold, and then observed in an electron microscope, using a Japanese Hitachi SM8020 field emission scanning electron microscope”. Thank you.

7、In figure 12 put all the axes on the same scale.

We have updated the legend and standardized its scale. Thank you.

8、Change throughout the manuscript "substitution rate" to "substitution percentage".

Thank you very much for your suggestion; we check the full text and replace it. Thank you.

9、Review the conclusions.

We have rewritten the conclusion to be concise and to highlight the experiment's objectives, as mentioned in the introduction. Thank you.

(1)The compressive strength of MPC specimens decreases with increasing substitution percentages at all ages. The rate of strength loss is highest in the early stages of curing and decreases with curing time after that, with a maximum of 6.2% at age 28d for substitution percentages below 15%.

(2)The compression failure process of MPC can be divided into three stages based on the characteristics of the AE count changes. With the increase of marble powder substitution percentage, the peak of acoustic emission accumulation count decreased, but the acoustic emission activity at the beginning of loading increased, indicating that the original defects of MPC were more. At the same time, the relative stress at critical instability failure decreases with the substitution percentage, and the substitution percentage decreases by 4.2% at 15%.

(3)The RA-AF correlation analysis showed that the tensile mode damage was the main fracture form of MPC. As the marble powder substitution percentage increases, the percentage of tensile mode cracks decreases in stages I and II, the number of shear mode cracks increases, and the percentage in stage III tends to increase. The damage characteristics gradually change from brittle to ductile. The SEM images and the macroscopic cracking behaviour of the failure support this result. The b-value analysis shows that the fluctuation of b-value increases with the increase of marble powder substitution percentage; the highest fluctuation is 18.5% at 15% substitution percentage, the number of unstable microcracks under pressure increases and the crack expansion behavior gradually changes from stable growth to non-stable growth.

(4)The MPC damage evolution model was established with cumulative AE counts. The results showed that when the substitution percentage was lower than 15%, the damage development of MPC was relatively slow in the middle stress (relative stress 20%-70%) and accelerated after reaching 70%.

Special thanks to you for your good comments.

Thanks!

Best regards!

Author Response File: Author Response.pdf

Reviewer 3 Report

1. Kindly work on the aim and objective of the article. These are important attributes for a research article.

2. It is hard to clarify the objective. The article discusses methodology as well as material behavior though, none of them have been clearly and extensively discussed.

3. Why the acoustic emission method of testing is proposed? In what capacity it will enhance the understanding of the researchers on the behavioral aspects of the material under loading?

4. If the article is specially designed to focus on test methodology, there are plenty of things either not mentioned or missing. For example, what are the limitations, critical test conditions, affecting parameters of the acoustic emission test method?

5. How the test using AE apparatus were conducted? Where are the test setup images, details of arrangement of major and minor assemblies?

6. How the measurement were observed and recorded? What were the factors considered and neglected during the testing of the specimens using AE?

7. Other than the literature, what are the standards available to follow the AE method in concrete testing? If not, what is the justification of using this method?

8. Regarding the study on concrete with marble wastes, what is the novelty of the work? What specific data set, results and significant scientific details have been revealed those were not known yet? Novelty part must be highlighted clearly for any research.

9. As far as the study and observations on the three stage response of the specimen, to what extent these responses differ from the normal concrete and what is the reason for the same? In other words, the clear role of the inclusion of the marble powder has not been mentioned explicitly.

10. The discussion between the line 233 to 270 is interesting but how these attributes were confirmed exactly? SEM imaging does not answer the discussion points mention in the paragraph, hence on what basis the detailed information has been mentioned? Utilize some supportive references for this and add them into the claims made.

11. Figure 2 is an illustration. Kindly use real images always for such novel testing methods.

12. No conclusion on feasibility or adequacy of using the AE method for such testing? Why?

13. What is the scope of the work presented? Are there any novel analytical or characteristic comparison carried out? These are necessary aspects.

14. Overall, The authors may rework on aim, objective and scope of the concepts namely using the AE method in testing or influence of marble powder on strength response. Both are largely huge areas to address and require in depth discussion. Herein, both the concepts are discussed non contextually together.

Author Response

Dear reviewer:

The part has been revised according to your comments. Revision notes are given as follows:

Kindly work on the aim and objective of the article. These are important attributes for a research article.

Thank you very much for your constructive comments on this article. We have reconceived the article's structure, focusing on rewriting the abstract, introduction, and conclusion chapters. Firstly, in lines 35-47 of the introduction, the current state of research on marble powder concrete is presented, with a selection of representative references to illustrate. Then, in lines 48-54, the shortcomings of the present research are introduced, namely the lack of research on the fracture characteristics of marble powder concrete under compression, which is of great importance for practical engineering applications. The well-established applications of acoustic emission in concrete and the important findings obtained are presented in lines 55-66, which have similarities to this paper. Then in lines 66-70, the advantages of acoustic emission in this experiment are summarised, namely the accurate and simultaneous capture of information on the concrete fracture process under compression. In lines 71-76, we introduce the use of acoustic emission to study the compressive fracture properties of marble powder concrete and summarise the objectives of the following study. Also, we modified parts of the text (in red font) to enhance the achievement of the study objectives. We introduced references related to the results of the experiments in this paper for the explanation. Please refer to the section of the text in red for details of the changes made. Thank you.

It is hard to clarify the objective. The article discusses methodology as well as material behavior though, none of them have been clearly and extensively discussed.

The research objective of this paper is to apply acoustic emission techniques to the fracture characteristics of marble powder concrete, where the main analytical methods used are all typical of acoustic emission, i.e., parametric analysis, RA-AF correlation analysis (section 3.3), and the b-value method. We have focused on rewriting the abstract, introduction, and conclusion sections (in red font) to highlight the study's objectives while we have enhanced the analytical narrative of the purpose of the tests in the text. Thank you.

Why the acoustic emission method of testing is proposed? In what capacity it will enhance the understanding of the researchers on the behavioral aspects of the material under loading?

Regarding the application of acoustic emission technology in concrete, we have rewritten the introduction chapter (lines 55-70) to highlight the advantages of acoustic emission technology in the study of this paper, to strengthen the rigor of the article, and to illustrate the results of acoustic emission in the study of other concrete materials, applying the proven theoretical analysis methods in this paper. Thank you.

If the article is specially designed to focus on test methodology, there are plenty of things either not mentioned or missing. For example, what are the limitations, critical test conditions, affecting parameters of the acoustic emission test method?

This paper aims to conduct an experimental study of marble powder concrete by applying acoustic emission techniques. We have rewritten the abstract and introduction (lines 29-76) to highlight the test's key objectives. Thank you.

How the test using AE apparatus were conducted? Where are the test setup images, details of arrangement of major and minor assemblies?

The actual live shot has been re-added to the text regarding the layout details. The instrument's main parameter settings and test details are explained in 100-113 lines. Thank you.

How the measurement were observed and recorded? What were the factors considered and neglected during the testing of the specimens using AE?

The acoustic emission equipment in this article can automatically record the test data, and the acoustic emission count is the most efficient test data. During the experiment, to ensure that the acoustic emission equipment and the test press are started simultaneously, we re-added this description at line 112 of the text. External noise interferes the most with the test process, so before the start of the experiment, it is necessary to carry out pre-tests and set appropriate thresholds to exclude external factors' interference in the results; we re-added parameter setting instructions at lines 104-113 in the text. Thank you.

Other than the literature, what are the standards available to follow the AE method in concrete testing? If not, what is the justification of using this method?

Regarding the standard of AE testing, refer to the "Calibration Specification for Acoustic Emission Instrumentation" and based on a large number of literature reading for testing, the application of acoustic emission technology in the field of concrete is mature, many important theoretical analysis methods are widely used, and significant research results have been obtained, this section has been rewritten in the introduction at lines 55-70. Thank you.

Regarding the study on concrete with marble wastes, what is the novelty of the work? What specific data set, results and significant scientific details have been revealed those were not known yet? Novelty part must be highlighted clearly for any research.

About the current state of research on marble powder concrete we have rewritten the relevant part of the introduction and introduced the current state of research on marble powder concrete in lines 35-47 of the introduction, with a selection of representative references to illustrate. Then, in lines 47-54, we introduce the shortcomings of the present research, i.e., the lack of research on the fracture characteristics of marble powder concrete under compression, which is of great importance for practical engineering applications. Also, previous research results similar to the experimental results of this paper are introduced in the body of the article. Thank you.

As far as the study and observations on the three stage response of the specimen, to what extent these responses differ from the normal concrete and what is the reason for the same? In other words, the clear role of the inclusion of the marble powder has not been mentioned explicitly.

According to the different changes in acoustic emission count, we divide the compressive failure process of marble powder concrete into three stages. This visible result is the basis for analyzing the difference in fracture characteristics between marble powder concrete and plain concrete later. To this end, we have strengthened the writing of this section and put it in lines 165-189 to illustrate while adding the reasons for the difference. Re-enforce this section of the writing in the RA-AF correlation analysis method section (in red font) below as well. Thank you.

The discussion between the line 233 to 270 is interesting but how these attributes were confirmed exactly? SEM imaging does not answer the discussion points mention in the paragraph, hence on what basis the detailed information has been mentioned? Utilize some supportive references for this and add them into the claims made.

Thank you very much for your constructive comments on this paper, which have been extremely helpful in improving the quality of the manuscript. We have carefully considered your suggestions, consulted many references, and summarised them to support this part of the discussion. On this basis, we have rewritten this section of the manuscript (lines 249-271 in red), streamlining the statements and adding references to validate them. Some notes have been added to the SEM images to explain the conclusions of this section. Thank you.

Figure 2 is an illustration. Kindly use real images always for such novel testing methods.

Thanks for your suggestion. We re-added live shots to the article. Thank you.

No conclusion on feasibility or adequacy of using the AE method for such testing? Why?

In this section, we have rewritten the relevant part of the introduction, described it in lines 55-70, and added literature similar to the tests in this paper.

What is the scope of the work presented? Are there any novel analytical or characteristic comparison carried out? These are necessary aspects.

For the work section, we have rewritten the introductory chapter. The first paragraph introduces the general background of the experiments in this paper at a macro level, followed by the current status of research related to marble powder concrete in the second paragraph, followed by the purpose and significance of the research in this paper at the end of the paragraph. The third paragraph introduces the research on applying acoustic emission in the field of concrete, which has led to more meaningful conclusions. Therefore acoustic emission was chosen to achieve the research objectives of this paper. We have also modified the conclusion section to provide a concise description of the findings in the text. Thank you.

Overall, The authors may rework on aim, objective and scope of the concepts namely using the AE method in testing or influence of marble powder on strength response. Both are largely huge areas to address and require in depth discussion. Herein, both the concepts are discussed non contextually together.

We have reconceived the article's structure, focusing on rewriting the abstract, introduction, and conclusion chapters. Firstly, in lines 35-47 of the introduction, the current state of research on marble powder concrete is presented, with a selection of representative references to illustrate this. Then, in lines 48-54, the shortcomings of the present research are introduced, namely the lack of research on the fracture characteristics of marble powder concrete under compression, which is of great importance for practical engineering applications. The well-established applications of acoustic emission in concrete and the important findings obtained are presented in lines 55-66, which have similarities to this paper. This is followed by a summary of the advantages of acoustic emission in this experiment, namely the accurate and simultaneous capture of information on the concrete fracture process under compression, in lines 66-70. In lines 71-76, we introduce the use of acoustic emission to study the compressive fracture properties of marble powder concrete and summarise the objectives of the following study. The body of the paper has also been revised to enhance the achievement of the research objectives in the introduction and to introduce a description of the literature related to the experimental results of this paper. The conclusion section has been rewritten to summarise the experimental findings concisely. Thank you.

Special thanks to you for your good comments.

Thanks!

Best regards!

Author Response File: Author Response.pdf

Reviewer 4 Report

This manuscript presents an experimental study in which the results of acoustic emissions on concrete specimens, produced with increasing replacements of Portland cement by marble powder, are evaluated. The study is interesting and is concerned with the use of industrial waste, that is, with a focus on the construction sustainability. However, to improve the paper quality, I believe that there are points that deserve to be clarified and discussed in more depth.

Major comments

It is understood that in the Introduction chapter, the authors must make clear the main justification for the relevance of the study developed. Is there any particular reason why marble powdered concrete should be the subject of acoustic emission tests? What do the authors advocate as different behavior from other types of concrete? Especially with other types of mineral additions. By the way, the authors cite some references of studies with acoustic emission, however in the chapter Results little or nothing is discussed compared to these mentioned studies.

In chapter 3, it is observed that the authors compare the results obtained, without discussing the reasons that influence each average result.

Minor comments

To better understand the variation of average compressive strengths, it will be interesting to know and see the values of standard deviations in the figures (in the form of bars, for example).

In subchapter 3.1, would it not be better to state that the main influence on the decrease in compressive strength comes from the reduction of cement content in the mixes?

In subchapter 3.2, a deeper discussion of the results is necessary. Explain why the increase in marble powder significantly affects the compressive failure behavior of concrete. Are there similar studies in the literature?

In Figure 9, why are percentages indicated in some result columns and not in others?

In the Conclusion chapter, it will be important, in addition to being revised considering the questions and doubts raised here, that it be made clear that the objectives of the study, advocated in the introduction, were achieved and how.

Author Response

Dear reviewer:

The part has been revised according to your comments. Revision notes are given as follows:

1、It is understood that in the Introduction chapter, the authors must make clear the main justification for the relevance of the study developed. Is there any particular reason why marble powdered concrete should be the subject of acoustic emission tests? What do the authors advocate as different behavior from other types of concrete? Especially with other types of mineral additions. By the way, the authors cite some references of studies with acoustic emission, however in the chapter Results little or nothing is discussed compared to these mentioned studies.

Thank you very much for your constructive comments on this article. We have reconceived the article's structure, focusing on rewriting the abstract, introduction, and conclusion chapters. Firstly, in lines 35-47 of the introduction, the current state of research on marble powder concrete is presented, with a selection of representative references to illustrate. Then, in lines 48-54, the shortcomings of the present research are introduced, namely the lack of research on the fracture characteristics of marble powder concrete under compression, which is of great importance for practical engineering applications. The well-established applications of acoustic emission in concrete and the important findings obtained are presented in lines 55-66, which have similarities to this paper. Then in lines 66-70, the advantages of acoustic emission in this experiment are summarised, namely the accurate and simultaneous capture of information on the concrete fracture process under compression. In lines 71-76, we introduce the use of acoustic emission to study the compressive fracture properties of marble powder concrete and summarise the objectives of the following study. We have placed the differences in fracture properties between marble dust and other mineral admixtures in the fourth section. Please refer to the four chapters, Abstract, Introduction, Discussion, and Conclusion, for details of the changes. Thank you.

2、In chapter 3, it is observed that the authors compare the results obtained, without discussing the reasons that influence each average result.

We have re-reviewed the relevant research literature to provide a causal analysis of the findings of this paper to support the discussion presented in this paper. Please refer to the section in red in Chapter 3 for details of the changes. Thank you.

3、To better understand the variation of average compressive strengths, it will be interesting to know and see the values of standard deviations in the figures (in the form of bars, for example). In subchapter 3.1, would it not be better to state that the main influence on the decrease in compressive strength comes from the reduction of cement content in the mixes?

Thank you very much for your important suggestion. We have included a description of the causes of the strength drop in marble dust concrete based on a review of the references with the literature source (Lines 131-141). Also, Figure 3 has been revised to a bar chart with error bars. Thank you again.

4、In subchapter 3.2, a deeper discussion of the results is necessary. Explain why the increase in marble powder significantly affects the compressive failure behavior of concrete. Are there similar studies in the literature?

The reasons used to validate the results of this paper were found by checking the references and are cited in this paper. Please refer to lines 177-189 for details of the amendments. Thank you.

5、In Figure 9, why are percentages indicated in some result columns and not in others?

When we created the diagram, we considered that it would be crowded if all percentages were included and that they were not all mentioned in the above article. We have taken your suggestion seriously, redrawn the diagram, and embellished it to include all the percentages to make it easier to read. Thank you.

6、In the Conclusion chapter, it will be important, in addition to being revised considering the questions and doubts raised here, that it be made clear that the objectives of the study, advocated in the introduction, were achieved and how.

We have carefully considered your suggestions above and have rewritten the conclusion to include a description of the implementation methods and to highlight the experimental objectives mentioned in the introduction. Please consult the conclusion in red for details of the changes. Thank you.

Special thanks to you for your good comments.

Thanks!

Best regards!

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Dear authors, thank you for considering all my recommendations. The manuscript under these conditions, in my opinion, is suitable for publication.

Reviewer 4 Report

After carefully reading the authors' responses to my recommendations, I consider that the new version of the submitted manuscript presents substantial improvements to its quality.

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Acoustic Emission Test of Marble Powder Concrete

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