Assessing the Impact of Fly Ash and Recycled Concrete Aggregates on Fibre-Reinforced Self-Compacting Concrete Strength and Durability
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsAccept in the present form.
Comments on the Quality of English Languagen.a
Author Response
Accept in the present form.
Response: Thank you for accepting our paper for publication.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe Manuscript "Assessing the impact of fly ash and recycled concrete aggregates on fibre-reinforced self-compacting concrete strength and durability" is well written, materials and methods are properly described but prior to publication I propose the following improvements:
1. Figures 1, 2, 4-6, and 8-11 are difficult to read (font size too small)
2. Lines 132-134: is this sentence correct? And it should be in the article?
3. Figure 8 and Table 10 show the same data. Please consider removing Table 10 from the text and placing it in the section: Supplementary Materials. Similarly, Table 11-13 and Figure 9-11.
4. Cement with a high quicklime content was selected for testing. Could this be important when we want to use fly ash additive? Please explain.
Author Response
The Manuscript "Assessing the impact of fly ash and recycled concrete aggregates on fibre-reinforced self-compacting concrete strength and durability" is well written, materials and methods are properly described but prior to publication I propose the following improvements:
- Figures 1, 2, 4-6, and 8-11 are difficult to read (font size too small)
Response: The suggestion has been incorporated. (Line 265, 297, 351, 383, 431, 540, 554, 590, 592)
- Lines 132-134: is this sentence correct? And it should be in the article?
Response: The suggestion has been incorporated and the suggested sentence was removed.
- Figure 8 and Table 10 show the same data. Please consider removing Table 10 from the text and placing it in the section: Supplementary Materials. Similarly, Table 11-13 and Figure 9-11.
Response: The suggestion has been incorporated. and the suggested sentence were moved to Supplementary materials section.
- Cement with a high quicklime content was selected for testing. Could this be important when we want to use fly ash additive? Please explain.
Response: Quicklime [CaO] in cement forms calcium hydroxide [Ca(OH)â‚‚] when it comes into contact with water, which catalyses the hydration process. Fly ash being a pozzolanic material further reacts with free calcium hydroxide present in the A-G paste to form additional cementitious compounds mainly C-S-H. This pozzolanic reaction results in greater strength and durability of concrete by contributing more C-S-H than the normal cement, thereby improving on the strength of the concrete structure.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors presented a well-organized study on the impact of fly ash and recycled aggregate on the fresh and hardened properties of self-compacting concrete. The study is very meaningful and the manuscript is well prepared. Though the idea is not new, the authors managed to conduct the research thoroughly. There are only a few minor concerns from the reviewer that need to be answered before the manuscript is ready to be published.
1. It is not common to have a separate literature review section after the introduction. The reviewer does not see the necessity of this section. It is recommended that this part be shortened, the studies are concisely summarized, and they are put in the introduction.
2. In Table 4, the elongation index, fineness modulus and flakiness index of the natural aggregate and the recycled aggregate are very different. How would the author justify that the change of the properties is not the result of the differences in these parameters?
3. Line 334: The reviewer would like to suggest the author cite the references for the equation.
4. The SEM figures do make the manuscript look better, but there should be some description that tells the reader what they are looking at and what is special enough to be shown in the paper. For example, in line 304, for Figure 3, the image still looks porous as there is no comparison. It might be better if the author labels the features of the image.
5. The conclusion section is a little too long for the reviewer.
Author Response
The authors presented a well-organized study on the impact of fly ash and recycled aggregate on the fresh and hardened properties of self-compacting concrete. The study is very meaningful and the manuscript is well prepared. Though the idea is not new, the authors managed to conduct the research thoroughly. There are only a few minor concerns from the reviewer that need to be answered before the manuscript is ready to be published.
1. It is not common to have a separate literature review section after the introduction. The reviewer does not see the necessity of this section. It is recommended that this part be shortened, the studies are concisely summarized, and they are put in the introduction.
Response: The suggestion has been incorporated. (Line 107 – 124)
2. In Table 4, the elongation index, fineness modulus and flakiness index of the natural aggregate and the recycled aggregate are very different. How would the author justify that the change of the properties is not the result of the differences in these parameters?
Response: Based on the preliminary stages of this investigation, it is observed that the changes in concrete properties are not due to differences in the elongation index, fineness modulus, and flakiness index of the different types of aggregates used. To support this assertion, the preliminary stage results were compared with existing literature where similar comparisons between normal and recycled aggregates were made. Additionally, a series of mechanical tests were conducted on concrete samples made with both types of aggregates, and it was found that the performance differences aligned more closely with the aggregate type rather than the indices. (Line 173 – 180)
3. Line 334: The reviewer would like to suggest the author cite the references for the equation.
Response: The suggestion has been incorporated. (Line 355 – 358)
4. The SEM figures do make the manuscript look better, but there should be some description that tells the reader what they are looking at and what is special enough to be shown in the paper. For example, in line 304, for Figure 3, the image still looks porous as there is no comparison. It might be better if the author labels the features of the image.
Response: The suggestion has been incorporated. (Line 315)
5. The conclusion section is a little too long for the reviewer.
Response: The suggestion has been incorporated. (Line 681 – 704)
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThe article evaluates the effects of fly ash, polypropylene fiber, and recycled concrete aggregates on the strength and durability of self-compacting concrete. The topic is relevant in modern conditions of the constantly growing demand for building materials and related environmental problems. The presented research results confirm the possibility of developing construction solutions that reduce dependence on primary resources and increase the quality of concrete structures.
In general, the article is assessed positively, but there are some comments:
- The content of Section 4 and the related Table 5 is not entirely clear; is this a control composition for the entire set of experiments?
- Section 5 states that this paper presents the results of an optimization study of four variables - fly ash, polypropylene fiber, recycled concrete aggregates of two fractions content. However, the article lacks research on different fly ash contents. The control composition contains 50% fly ash by weight of the binder and this content does not change. The description of the experimental program should be clarified.
- Also, in Section 5, it is unreasonable to evaluate the results obtained as “Effect of HVFA and Fiber Content on Workability Properties of SCC”, since there are no control data for mixtures that do not contain fly ash. Specifically for the data presented in Tables 6 and 7 and in Figures 1 and 2, we can talk about “Effect of Fiber Content on Properties of Self-Compacting Concrete incorporating High-Volume Fly Ash.”
- Lines 298-305. It follows from the text that the conclusion about the effect of fly ash on the strength of concrete was made personally by the authors. However, the article does not contain research data that confirms this statement; there is no data for compositions without fly ash. Perhaps the reference is to previous studies, in which case a link to these studies should be added.
- Figure 4. The feasibility of constructing a graph of the dependence of compressive strength on the Ultrasonic Pulse Velocity is questionable. The UPV depends on the structure and this is well described in the presented article when analyzing the influence of aggregates on the properties of the mixture. Perhaps the effect of polypropylene fiber content on the UPV and structure of the composite should be assessed?
- A clarification regarding polypropylene fiber content should be added. Did the authors mean a fiber content of 0% to 1% by weight of the binder?
- References to Figures 2, 6 and 10 and Table 1 should be added in the text containing their analysis.
- Line 484 – the closed bracket character “)” is missing.
The article presents the results of a volumetric experiment. This article will contribute to the development of technology for using recycled materials in construction and will be useful for specialists working with similar materials. The article may be accepted for publication after making appropriate corrections.
Author Response
The article evaluates the effects of fly ash, polypropylene fiber, and recycled concrete aggregates on the strength and durability of self-compacting concrete. The topic is relevant in modern conditions of the constantly growing demand for building materials and related environmental problems. The presented research results confirm the possibility of developing construction solutions that reduce dependence on primary resources and increase the quality of concrete structures.
In general, the article is assessed positively, but there are some comments:
- The content of Section 4 and the related Table 5 is not entirely clear; is this a control composition for the entire set of experiments?
The suggestion has been incorporated. (Line 201 – 208)
- Section 5 states that this paper presents the results of an optimization study of four variables - fly ash, polypropylene fiber, recycled concrete aggregates of two fractions content. However, the article lacks research on different fly ash contents. The control composition contains 50% fly ash by weight of the binder and this content does not change. The description of the experimental program should be clarified.
The suggestion has been incorporated. (Line 216 – 219, Line 222 - 230)
- Also, in Section 5, it is unreasonable to evaluate the results obtained as “Effect of HVFA and Fiber Content on Workability Properties of SCC”, since there are no control data for mixtures that do not contain fly Specifically for the data presented in Tables 6 and 7 and in Figures 1 and 2, we can talk about “Effect of Fiber Content on Properties of Self-Compacting Concrete incorporating High-Volume Fly Ash.”
The suggestion has been incorporated. (Line 254, 266, 296, 297)
- Lines 298-305. It follows from the text that the conclusion about the effect of fly ash on the strength of concrete was made personally by the authors. However, the article does not contain research data that confirms this statement; there is no data for compositions without fly ash. Perhaps the reference is to previous studies, in which case a link to these studies should be added.
The suggestion has been incorporated. (Line 308)
- Figure 4. The feasibility of constructing a graph of the dependence of compressive strength on the Ultrasonic Pulse Velocityis questionable. The UPV depends on the structure and this is well described in the presented article when analyzing the influence of aggregates on the properties of the mixture. Perhaps the effect of polypropylene fiber content on the UPV and structure of the composite should be assessed?
The suggestion has been incorporated. (Line 337 – 342)
- A clarification regarding polypropylene fiber content should be added. Did the authors mean a fiber content of 0% to 1% by weight of the binder?
The suggestion has been incorporated. (Line 225)
- References to Figures 2, 6 and 10 and Table 1 should be added in the text containing their analysis.
The suggestion has been incorporated. (Line 131, 301, 434, 675)
- Line 484 – the closed bracket character “)” is missing.
The suggestion has been incorporated.
Author Response File: Author Response.pdf
Reviewer 5 Report
Comments and Suggestions for AuthorsThe paper submitted by the authors has serious shortcomings and I have doubts about its suitability for the journal. There are many errors throughout the manuscript and its presentation leaves much to be desired.
Here are some of the considerations I found:
Authors should select the Type of the Paper
The title should be in journal format, with the first letter of each word capitalised.
The abstract is excessively long, and should be specific with the most relevant points and results of the research.
The introduction and the state of the art should be more in-depth, including more recent references relevant to the research. Please note that in the literature review, except for one reference, the rest are prior to 2014. In the last 10 years a lot of work has been done on fly ash recovery and the authors should make an effort to update the document.
Standards should be referenced.
Have the properties in Table 1 been measured by the authors? If so, please indicate how, and if not, indicate where the information was obtained. Idem for Table 2.
Table 3, the units are missing. In addition, this table provides relevant information that should be discussed.
Indicate how the properties of the aggregates have been obtained.
Indicate where the information for fibres has been obtained from.
Sections 3, 4 and 5 should be part of the subsections 3. Materials and Methods.
Section 4, which should be 3.2.2. should be renamed, as it is poorly translated.
A granulometry curve for aggregates should be included.
On the basis of what criteria has this water/cement ratio been selected?
Line 220, change Tabel to Table.
In section 5 --> 3.2.3. it should be indicated how the tests are carried out, and later, in section 4. Results and Discussion, the graphs and tables obtained should be presented and discussed.
Figure 1 is very poor and there is a lack of legends on the vertical axes.
An in-depth discussion of Figure 3 is missing. It also seems a bit odd that the image is from the year 2022.
In Figure 4, how many samples of each type have been analysed, how can the authors be sure that this is an exponential trend and not linear (or quadratic as one would expect), this analysis does not make much sense.
In Fig. 5, the variability in the trials should be included.
Table 9, what does d mean, on the basis of which criteria this number of days has been selected. Always use the same number of significant figures.
The section on durability can be much improved, the discussion of the results is scarce and they are not compared with previous studies. What is the impact of this study? What relevance does it have?
Future lines of research should be included in the conclusions.
The bibliography is not formatted.
Additionally, the writing in English leaves much to be desired and the article should be reviewed by a native expert.
Comments on the Quality of English LanguageAdditionally, the writing in English leaves much to be desired and the article should be reviewed by a native expert.
Author Response
Reviewer 5
The paper submitted by the authors has serious shortcomings and I have doubts about its suitability for the journal. There are many errors throughout the manuscript and its presentation leaves much to be desired. Here are some of the considerations I found:
- Authors should select the Type of the Paper
Response: The suggestion has been incorporated in Line 1
- The title should be in journal format, with the first letter of each word capitalised.
Response: The suggestion has been incorporated in Line 2 – 4.
- The abstract is excessively long, and should be specific with the most relevant points and results of the research.
Response: The suggestion has been incorporated in Line 11 – 31.
- The introduction and the state of the art should be more in-depth, including more recent references relevant to the research. Please note that in the literature review, except for one reference, the rest are prior to 2014. In the last 10 years a lot of work has been done on fly ash recovery and the authors should make an effort to update the document.
Response: The suggestion has been incorporated in Line 36 – 124.
- Standards should be referenced.
Response: The suggestion has been incorporated in Line 128, 136, 159.
- Have the properties in Table 1 been measured by the authors? If so, please indicate how, and if not, indicate where the information was obtained. Idem for Table 2.
Response: The suggestion has been incorporated in Line 130 – 132, Line 137.
- Table 3, the units are missing. In addition, this table provides relevant information that should be discussed.
Response: The suggestion has been incorporated in Line 131.
- Indicate how the properties of the aggregates have been obtained.
Response: The suggestion has been incorporated in Line 162 – 168.
- Indicate where the information for fibres has been obtained from.
Response: The suggestion has been incorporated in Line 183 – 184.
- Sections 3, 4 and 5 should be part of the subsections 3. Materials and Methods.
Section 4, which should be 3.2.2. should be renamed, as it is poorly translated. A granulometry curve for aggregates should be included.
Response: The suggestion has been incorporated in Line 170.
- On the basis of what criteria has this water/cement ratio been selected?
Response: The suggestion has been incorporated in Line 210 – 213.
- Line 220, change Tabel to Table.
Response: The suggestion has been incorporated in Line 209.
- In section 5 --> 3.2.3. it should be indicated how the tests are carried out, and later, in section 4. Results and Discussion, the graphs and tables obtained should be presented and discussed. Figure 1 is very poor and there is a lack of legends on the vertical axes.
Response: The reviewers’ corrections have been incorporated. Since four vertical axes were used, legends were provided at top with different colour code. (Line 265)
- An in-depth discussion of Figure 3 is missing. It also seems a bit odd that the image is from the year 2022.
Response: The suggestion has been incorporated in Line 317 – 322.
- In Figure 4, how many samples of each type have been analysed, how can the authors be sure that this is an exponential trend and not linear (or quadratic as one would expect), this analysis does not make much sense.
Response: The suggestion has been incorporated in Line 358 – 367.
- In Fig. 5, the variability in the trials should be included.
Response: The suggestion has been incorporated in Line 383.
- Table 9, what does d mean, on the basis of which criteria this number of days has been selected. Always use the same number of significant figures.
Response: The suggestion has been incorporated in Line 293 – 295.
- The section on durability can be much improved, the discussion of the results is scarce and they are not compared with previous studies. What is the impact of this study? What relevance does it have?
Response: The suggestion has been incorporated in Line 511 – 518.
- Future lines of research should be included in the conclusions.
Response: The suggestion has been incorporated in Line 705 – 712.
- The bibliography is not formatted.
Response: The suggestion has been incorporated in Line 723 – 802.
Author Response File: Author Response.pdf
Round 2
Reviewer 5 Report
Comments and Suggestions for AuthorsThe authors have made a great effort to improve the manuscript and enhance the quality of the publication. Some unresolved changes are indicated.
The bibliography should appear in order.
Indicate in Figure 1 the reference standard. In addition, the percentage on the Y-axis should be in brackets.
Figure 3 is very pretentious and risky. It would be advisable to change it to a bar chart and include the error in it. As it stands, the adjustments made do not appear and do not corroborate the theoretical model.
Author Response
The authors have made a great effort to improve the manuscript and enhance the quality of the publication. Some unresolved changes are indicated.
- The bibliography should appear in order.
Response: Thank you for the suggestion, Correction has been carried out
- Indicate in Figure 1 the reference standard. In addition, the percentage on the Y-axis should be in brackets.
Response: Thank you for the suggestion, Correction has been carried out
- Figure 3 is very pretentious and risky. It would be advisable to change it to a bar chart and include the error in it. As it stands, the adjustments made do not appear and do not corroborate the theoretical model.
Response: Thank you for the suggestion, Correction has been carried out
Author Response File: 
Author Response.docx
