Examination of Mixing Proportion in Self-Compacting Gangue-Based Pavement Concrete

Round 1

Reviewer 1 Report

3. Results and discussion

3.1. Aggregate industry analysis - no comparative analysis with other authors.

3.2 Slump flow – 13,24

3.3 Compressive strength – 5, 25, 24, 26

3.4 Splitting strength - no comparative analysis with other authors.

3.5 Experimental results of abrasion resistance - no comparative analysis with other authors.

No comparative analysis in relation to other authors, use of only 5 items. This is a modest analysis.

5. Xiangyu Su(2021), Experimental Research on Basic Mechanical Properties of Coal Gangue Concrete [D]. Xi ’ an University of 605 Architecture & Technology
6. Shi X X, Liu Y X, Pu Q, Tian Y and Chen J J (2017), Effect of highly efficient water-reducing agent and fly ash on the perfor- 622 mance of self-compacting concrete Concrete and Cement Products (12) 14-18
7. J. Wei (2018), Study on the preparation and performance of low-air-entraining polycarboxylate superplasticizer, Shandong Uni- 644 versity,Jinan,Shandong,China,2018. 645
8. Samuel Demie, Muhd Fadhil Nuruddin , Nasir Shafiq (2013), Effects of micro-structure characteristics of interfacial transition 646 zone on the compressive strength of self-compacting geopolymer concrete, Construction and Building Materials 41:91-98. 647
9. Eva Vejmelková, Martin Keppert, Stefania Grzeszczyk, Bartłomiej Skalinski, Robert Cerny (2011). Properties of self-compacting 648 concrete mixtures containing metakaolin and blast furnace slag. Construction & Building Materials 25:1325–1331.

Author Response

We would like to thank you for your careful reading, helpful comments, and constructive suggestions, which has significantly improved the presentation of our manuscript. We made the following modifications.

1.Based on your valuable suggestions, we have added some related literatures in the corresponding positions of the article for comparison, as shown in references [31], [32], [37] and [38].

Author Response File: Author Response.docx

Reviewer 2 Report

Dear Authors,
Thank you for the opportunity to review this article.
The importance of using secondary raw materials - such as gangue - in building materials is great. 
Because it is a very unconventional material, this topic is all the more interesting. 

I have to say that the language of the article is not good - it is not easy to read and that is wrong. 
If you used automatic 

The title is clear enough and the abstract looks reasonable and plausible. 

The introductory section matches the scope of the topic. 
I would recommend adding a few lines on the importance of sustainability of new materials and new practices and studying them outside Asia, for example:
10.1617/s11527-020-01535-3
10.3390/buildings11100454
10.3390/polym14040682

The description of the basic material is adequate but deserves more care. 
The description of the experiments is understandable. All methods and standards have not been cited. 

The results are interesting in terms of expectations. Their description can be understood, although it is very complicated because of the language. With all due respect, it is sometimes difficult to understand. 

The conclusions are consistent with the observations but lack scientific information. 

Some information:
- the format of the text is not good - errors in line spacing, spacing, text flow
- graphs are inappropriate, sometimes confusing, each in a different format
- the pictures are small, it is not easy to see what I represent
- missing mandatory parts of the text from the template,
- tables are inappropriately formatted.

 

 

Author Response

We would like to thank you for your careful reading, helpful comments, and constructive suggestions, which has significantly improved the presentation of our manuscript. We made the following modifications.

1.Thank for your comments. We have thoroughly checked and corrected the grammatical errors and typos we found in our revised manuscript.

2.Based on your valuable suggestions, we have increased the importance of sustainability regarding new materials and practices, as shown in refs [1],[2],[5],[6] and [7].

3.Based on your valuable suggestions, we have cited experimental methods and standards, as shown in refs[29] and[30].The ITZ microscopic test have no relevant standards for the prescribed experimental methods. The author have designed a reasonable test protocol based on the methods of researchers in other literature.

4.Based on your valuable suggestions, we have carefully reviewed and formatted the text.

5.Based on your valuable suggestions, we modified all images with appropriate resizing.

6.Based on your valuable suggestion, we have adjusted all the tables to keep the same size.

Author Response File: Author Response.docx

Reviewer 3 Report

This paper presents the investigation on the properties of self-compacting gangue-based concrete. In particular, the authors evaluated the effect of various dosages of gangue aggregate, fly ash, superplasticizer and steel fibers on the fluidity of fresh concrete mix as well as the compressive strength, the tensile splitting strength and the wear resistance of hardened concrete. The authors made also an attempt to investigate the ITZ (Interface Transition Zone) between the gangue aggregate and cement matrix by means of SEM/EDS.

As indicated by the authors, several attempts of the application of gangue, i.e. the waste by-product material coming from coal mining and processing, as an aggregate in concrete have been reported over past years. Indeed, the fact that the environmentally harmful gangue is usually stored for a long time affecting the ecological balance makes these studies extremely important. I believe that the potential application of gangue in self-compacting fiber-reinforced pavement concrete is an interesting and promising research path that has not been fully explored yet. However, the critical issues of this paper are described below.

Main comments:

1. Unfortunately, the quality of English language and style of the paper requires extensive editing, since some parts of the paper are hardly understandable.

2. Materials: Since the main properties of aggregate, such as the chemical composition, the pore size distribution and density, the water absorption, the crushing value etc. are extremely important regarding the final properties of concrete, the new aggregate material, i.e. gangue in this study, should be fully characterized. The information about the crushing value, the water absorption and the pore size distribution of gangue should be added to the paper.

3. Concrete samples: In my opinion, the clear identification of the effect of, for example, fly ash on the properties of concrete requires the preparation of a batch of samples containing various amounts of fly ash and constant amount of other components. According to Tab. 5, such batch of samples was not prepared within this study. Each time, when the amount of fly ash was changed, the amount of steel fibers was also changing. This creates serious difficulties in the interpretation of the results – how can we know if the increase/decrease of the strength is really an effect of fly ash and not the fibers? Moreover, have the authors prepared also the control groups of samples corresponding to each group of samples with changing component: one for “fly ash” group of samples, another one for “gangue” group of samples etc.? These results are not presented in the paper.

4. ITZ observation: On the basis of SEM/EDS investigation, the authors conclude that the ITZ for gangue samples is denser, with smaller pores and higher formation of AFT and AFT crystals, but were these results confirmed by any other characterization technique?

5. Figures: In my opinion, the graphs showing the effect of different dosages of various materials, i.e. gangue, fly ash, PCE and steel fibers in one graph (Fig. 10, 11, 18) are very confusing, especially considering the fact that the results for the control groups (please see my comment above) are missing. Moreover, there are some figures/photos that are not necessary, for instance Fig. 5 and 7, cause they do not provide any new information/technique for Buildings readers. I believe also that the same photos should not be used in two different figures (see Fig. 7 and 20).

Author Response

We would like to thank you for your careful reading, helpful comments, and constructive suggestions, which has significantly improved the presentation of our manuscript. We made the following modifications:

1.Thank for your comments. We have thoroughly checked and corrected the grammatical errors and typos we found in our revised manuscript.

2.According to your valuable comments, we will add the main characteristics of gangue and limestone aggregates to the article, as shown in Table 3.

3.Thanks for your valuable advice. In fact, we have also considered conducting the study with a controlled variable method, which allows for a control group for each variable. In order to obtain the optimal proportioning scheme for self-compacting gangue concrete, this study involves four research variables (the proportion of gangue, the proportion of steel fiber, the proportion of superplasticizer, and the proportion of fly ash). When using the control variable method, it is difficult to fix the rate of the other three factors to a certain value, which will greatly increase the difficulty and workload of the study, and the results will not be the best. Therefore, a more appropriate orthogonal experiment was chosen for this study, but at the same time it was difficult to set up a control group for each of the variables. It has to be admitted that the factors may have an effect in the orthogonal experiments, but the study has generally arrived at the appropriate dosing for each factor and the scientific validity of the proportioning scheme has been verified by the analysis of the field trials.

4.Thank you for your valuable suggestions. We have used representative SEM experiments and EDS experiments to study the ITZ characteristics of gangue and limestone, and presented them to readers in a more intuitive way. At the same time, combined with a large number of studies by other scholars, this phenomenon can be understood. Although the method of X-ray diffraction can quantitatively characterize the crystals in the ITZ region. In fact, in the current research, it is difficult to accurately extract the ITZ product, and the extraction may even cause damage to the ITZ product, affecting the accuracy of the experimental results. We will try our best to overcome this problem in the next step, and look forward to the guidance of reviewers.

5.Thanks for your valuable suggestion. We have optimized the graphs 9, 17, and 20, and reflected the experimental results of group 10 in the graph. However, as shown in the response to the third question, it is difficult to set a control group for each variable; Figure 5 and Figure 7 show the experimental flow of some experiments. Combined with your valuable suggestion, we have deleted Figure 5 and Figure 7.

Round 2

Reviewer 2 Report

Based on the previous review and your reactions, I can say that I can see an improvement. However, some aspects are still not ideal. The introduction is slightly confusing, although it already makes more sense. 
Furthermore, the results confront even more with the results of other studies, for example:
10.3390/math10020229
10.3390/ma14237347

The conclusions should be more concise. 

Still missing mandatory text sections after the conclusions. 
Please review the template thoroughly. 

Author Response

We would like to thank you for your careful reading, helpful comments, and constructive suggestions, which has significantly improved the presentation of our manuscript. We made the following modifications:

1. According to what you pointed out, our results contradict the article you provided. We read these two articles carefully and these two articles have benefited me a lot. For the first article, the influence of steel fiber in lightweight red ceramic waste aggregate concrete is studied, Since there are differences between lightweight aggregate concrete and SCC in admixtures, aggregate type and content, water cement ratio and so on, the differences in conclusions can be understood. For the second article, the author studied the lightweight fiber reinforced concrete modified by micro silica, and comes to the conclusion that the best mixing rate of micro silica is 10%. At this time, the concrete has higher strength because of its more dense C-S-H structure. In this regard, we agree with this view, which is also conducive to our next work. Due to different proportioning materials, it is understandable that there are differences in the microstructure of concrete. Needle rod AFT crystal can also improve the compactness of ITZ and prevent the formation of Ca (OH)₂ to a certain extent. We think this is not in conflict with the conclusion of this article. We think these two articles are very helpful to our research, and we have quoted them, as shown in references 21 and 26. We also made optimization adjustments in the introduction part.
2. Thank you for your valuable suggestions, we have simplified the conclusions.
3. According to your advice, the mandatory text has been added after the conclusions.

Author Response File: Author Response.docx

Reviewer 3 Report

Dear Authors,

Thank you for the consideration of all my review comments and for the answers to my questions.

I can see that significant changes have been made in your paper. The English language and style have been also noticeably improved.

Nevertheless I have still some serious doubts about the presentation and discussion of the results. First of all, you have introduced the red lines in the graphs of Figures 9 and 17 that show, as I assume, the results obtained for the reference sample. I think that it is a good idea, but I did not find any explanation of that line neither in the text, nor in the figure caption. I should be added to the paper.

The labeling of the samples is also a bit confusing. In Table 5 showing different compositions of your samples, you introduce the column called “Factors” with number from 1 to 10, while in Table 8 showing the results, there is a column called “Groups”. If the numbers 1-10 correspond to the same samples, the columns should be labelled in the same way.

The error bars are missing in Figure 8, 9 and 17. Moreover, in order to fully interpret and discuss the results shown in Figures 8, 9 and 17, the reader should be able to check the exact composition of the samples standing behind the particular points in the graph. The points in the graph should correspond to Group/Factor numbers 1-10. For this aim, I was trying to use Table 8, but unfortunately the values that you are showing in Figures 8, 9 and 17 cannot be found there. For example: Figure 8, the first graph, slump flow, different dosages of fly ash – in the graph we can find values as follows: 716, 732, 745. These values cannot be found in Table 8, so which group of samples we see here? What is the exact composition of these samples?

Author Response

We would like to thank you for your careful reading, helpful comments, and constructive suggestions, which has significantly improved the presentation of our manuscript. We made the following modifications:

1. Thank you for your valuable suggestions, we added the results of the control group to the paper, such as the marking part.
2. According to your valuable advice, We turn the "Factors" in Table 5 into "Groups" and reviewed all the markings.
3. Thank you for your valuable suggestions. The data points in Figure 9, Figure 10, Figure 18 and Figure 21 represent the average value of this factor at different levels, and the results are listed in Table 9. In addition, in order to intuitively describe the influence of various factors on the experiment, we show the results of range and standard deviation in the form of histogram, as shown in Figure 8. After careful consideration, it may not be accurate to calculate the deviation based on three groups of experimental results with the same level of each factor, because this result will be affected by other variables, resulting in inaccurate deviation. Therefore, it is considered to delete the error bars in Figure 9, figure 10, Figure 18 and Figure 21.

Author Response File: Author Response.docx

Round 3

Reviewer 3 Report

Dear Authors,

Thank you for the consideration of all my review comments and for the answers to my questions. I can see that significant changes have been made in your paper. 

Author Response

Thank you again for your consideration of our articles and for your valuable suggestions, which have made our articles even better, good luck with your work and enjoy your life!