Synergistic Effect of Micro-Silica and Recycled Tyre Steel Fiber on the Properties of High-Performance Recycled Aggregate Concrete
and Saleh Alsulamy 6
Round 1
Reviewer 1 Report
Paper ID: sustainability-2335944
Type:Article
Title: Synergistic effect of micro-silica and recycled tyre steel fiber on the properties of high-performance recycled aggregate concrete
Authors: Muhammad Talha Amir , Sobia Riaz , Hawreen Ahmed , Syed Safdar Raza , Ahmed Ali A. Shohan , Saleh Alsulamy
This paper investigates the mechanical and physical properties of recycled aggregate concrete (RAC) modified with micro-silica (MS) and recycled tire steel fiber (RTSF). Although the testing methods and compared results attained in the present study show the importance of the paper, this paper is a technical report rather scientific paper.
1. Novelty in comparison to recent literature? “To address the drawbacks of RAC, researchers have preferred using additional cementitious materials like silica fume/micro-silica, metakaolin, slag, fly ash, etc.” as the authors stated, so many studies about silica fume or micro silica -based recycled aggregate concrete and their performance. What is new?
2. Please provide chemical and physical properties of cement.
3. For mixing: Which standard did the authors comply with?
4. 100 x 200 mm or else: please do not use “x”. Please change it “×”.
5. Please give details of test methods.
6. Fig 4: please add error bar.
7. “While MS addition caused a significant reduction in the porosity of concrete”. …….. so what?
8. There are problems with tense use harmony. Some results are given in the present tense and some in the simple past.
- Throughout the text, some typos must be eliminated.
10. I strongly suggest for authors present their conclusions more concisely, avoiding repetition of the obvious and simple results.
Author Response
Reviewer # 1 (CHANGES ARE MARKED RED)
This paper investigates the mechanical and physical properties of recycled aggregate concrete (RAC) modified with micro-silica (MS) and recycled tire steel fiber (RTSF). Although the testing methods and compared results attained in the present study show the importance of the paper, this paper is a technical report rather scientific paper.
Thank you very much for taking the time to review my paper. Your feedback was incredibly valuable and has helped me to improve the quality of my work. I sincerely appreciate your efforts and expertise in providing such thoughtful comments.
Comment 1: Novelty in comparison to recent literature? “To address the drawbacks of RAC, researchers have preferred using additional cementitious materials like silica fume/micro-silica, metakaolin, slag, fly ash, etc.” as the authors stated, so many studies about silica fume or micro silica -based recycled aggregate concrete and their performance. What is new?
Response (L96-100): Thank you for your deep insights. The novelty is highlighted in the last paragraph of the introduction.
Comment 2: Please provide chemical and physical properties of cement.
Response (Table 1): The properties of cement have been added in Table 1.
Comment 3: For mixing: Which standard did the authors comply with?
Response (L175): No particular standard was adopted, the mixing technique has been decided after the extensive literature review and lab experience of mixing fibre-reinforced concrete in the concrete laboratory. The mixing procedure is thoroughly elaborated.
Comment 4: 100 x 200 mm or else: please do not use “x”. Please change it “×”.
Response (L196): Complied.
Comment 5: Please give details of test methods.
Response: All necessary details are provided. The test methods have been adopted from the established standards. The standard details are also provided.
Comment 6: Fig 4: please add error bar.
Response (Fig. 4): Complied.
Comment 7: “While MS addition caused a significant reduction in the porosity of concrete”. …….. so what?
Response (L435): This conclusion point has been revised.
Comment 8: There are problems with tense use harmony. Some results are given in the present tense and some in the simple past. Throughout the text, some typos must be eliminated.
Response: We have revised the manuscript to address these concerns.
Comment 10: I strongly suggest for authors present their conclusions more concisely, avoiding repetition of the obvious and simple results.
Response (See conclusions section): The conclusion section has been carefully revised considering the reviewer’s comment.
Reviewer 2 Report
Major revision is needed.
1.one data set can be used in one kind of plotting. Therefore, some figures should be deleted. For example, the same set of strength data is used in Fig.5 and Fig.6.
2. what is the innovation of your work? It should be highlighted.
3.The reference should be polished carefully. Some page No are missing in the papers published in Constr. Build. Mater.
4.author claimed that “interfacial transition zones (ITZs) within RCA play a negative role in reducing the strength of concrete [11], as ITZs act as weak links in any concrete matrix under compressive loads.”. how can you obtain this statement? Is such statement related to your compressive strength? At least, SEM test should be carried out to verify this statement.
5. the tense in the paper is very messy, for example, in Line 324 “Fine MS particles increase the meandering….”, in Line 326 “that RAC with 5% MS showed….”
6. with regards to “water absorption test”, the data is very messy, the detailed illustration should be added in this manuscript.
7. Some new and fiber-related studies could improve, such as Influences of MgO and PVA fiber on the abrasion and cracking resistance, pore structure and fractal features of hydraulic concrete; Comparison of fly ash, PVA fiber, MgO and shrinkage-reducing admixture on the frost resistance of face slab concrete via pore structural and fractal analysis
8.In fig.12, R2 is only 0.72, indicating the bad correlation. This figure should be deleted. The same for Fig.10.
9. Electrical resistivity of sample is related to content of steel fiber and porosity with conductive solution. Therefore, MIP tests should be carried out to verify the porosity of sample.
Author Response
Reviewer# 2 (CHANGES ARE MARKED BLUE)
Comment 1:.one data set can be used in one kind of plotting. Therefore, some figures should be deleted. For example, the same set of strength data is used in Fig.5 and Fig.6.
Response: I am grateful to you for dedicating your time to review my paper. Your feedback has been extremely useful, and it has helped me to enhance the quality of my work significantly. Your insightful comments demonstrate your expertise and effort, and I truly appreciate them.
We have removed the Fig. 6.
Comment 2:. what is the innovation of your work? It should be highlighted.
Response (L95-99): The innovation of our research work is highlighted in the last paragraph of the introduction section.
Comment 3:.The reference should be polished carefully. Some page No are missing in the papers published in Constr. Build. Mater.
Response: We have carefully revised the references. The page numbers for these references are not assigned yet.
Comment 4:. author claimed that “interfacial transition zones (ITZs) within RCA play a negative role in reducing the strength of concrete [11], as ITZs act as weak links in any concrete matrix under compressive loads.”. how can you obtain this statement? Is such statement related to your compressive strength? At least, SEM test should be carried out to verify this statement.
Response (L234-239): We understand that these microstructural investigations would significantly enhance the value and validity of our research work. However, we cannot carry out these specific investigations on our own, usually, SEM testing in many local institutes is possessed by physics and sciences departments, where the technicians lack the ability to conduct the specific SEM testing in concrete technology. However, this is a known fact that RCA has old ITZs within itself which also causes the strength reduction.
Comment 5: the tense in the paper is very messy, for example, in Line 324 “Fine MS particles increase the meandering….”, in Line 326 “that RAC with 5% MS showed….”
Response (L329-331): We have revised the entire paper to ensure the consistency of the tense use.
Comment 6:. with regards to “water absorption test”, the data is very messy, the detailed illustration should be added in this manuscript.
Response (L326-337): The results and discussion related to WA has been revised and re-arranged carefully.
Comment 7:. Some new and fiber-related studies could improve, such as Influences of MgO and PVA fiber on the abrasion and cracking resistance, pore structure and fractal features of hydraulic concrete; Comparison of fly ash, PVA fiber, MgO and shrinkage-reducing admixture on the frost resistance of face slab concrete via pore structural and fractal analysis.
Response (L70-72): Thank you for recommending us these useful studies. We have studied and found their relevance to our literature. Therefore, these have been included in the literature.
Comment 8:.In fig.12, R2 is only 0.72, indicating a bad correlation. This figure should be deleted. The same for Fig.10.
Response: The correlation sections have been removed.
Comment 9:. Electrical resistivity of sample is related to content of steel fiber and porosity with conductive solution. Therefore, MIP tests should be carried out to verify the porosity of sample.
Response: Though we understand the significance of modern testing techniques to verify the changes in the porosity of concrete by Mercury intrusion porosimeter (MIP), however, the authors have no access to MIP testing equipment or expertise. MIP testing requires specialized equipment and expertise that may not be available or feasible to obtain in our current situation. Therefore, we only limited to WA test results to investigate the change in the permeable porosity of concrete due to the addition of RTSF and MS. Moreover, we have tried our best to explain the change in electrical resistivity.
Reviewer 3 Report
In my opinion, the work presented can be published with some minor changes. The testing methods are appropriate for determining the most relevant properties (mechanical properties, durability), and a considerable effort has been made that is worth publishing. However, as a general rule, I believe that the number of samples is not sufficient to draw statistically significant conclusions, nor has a hypothesis test been conducted, so the study presented falls within the category of a pilot experiment, valid from a qualitative point of view and still very interesting for other researchers, but insufficient to draw significant conclusions from a quantitative point of view. Also, techniques for characterizing the microstructure of the tested mixtures have not been employed, which again prevents establishing certain types of conclusions. Consequently, the use of very definitive expressions pointing to quantitative effects should be avoided and replaced with conditional expressions more suitable for the type of experiment carried out.
Just as a suggestion, and without the acceptance of the article depending on it, I would like to recommend a recent work on the use of recycled fibers, in case the authors consider it appropriate to include it in their state-of-the-art review:
Residual strength and drying behavior of concrete reinforced with recycled steel fiber from tires, Revuelta, D., Carballosa, P., García Calvo, J.L., Pedrosa, F., Materials, 2021, 14(20), 6111
I include more specific comments below.
Line 71: “impact toughness” instead of “impact the toughness”
Lines 112-114: Where do these properties data of MS come from? Have they been obtained through tests? If so, please cite the test methods. If not, clarify that they come from the technical datasheet.
Line 123, Table 1: Please cite the test methods used to determine these properties.
Lines 188-197: How many samples have you used for the determination of these properties? Three, as for the mechanical properties? Please, specify.
Figure 4: If you have used three samples for the determination of density, please add deviation bars as in Fig. 5
Line 211: In my opinion, since you don’t perform any statistical hypothesis testing and with the number of samples used per batch (3 in some properties, others to be clarified if only one has been used), the experiment does not have enough statistical power to use the terms "significant" or "not significant". Although the conclusions are still interesting from a qualitative point of view, I suggest eliminating the use of such terms (significant/not significant) in the text, as it may lead to a misinterpretation by suggesting that the results are statistically significant. Perhaps the word “noticeable” could be a better choice.
Lines 220-226: Since you don’t have microstructural observations on your own samples to support these statements, I suggest the use of the conditional form (could be)
Line 242: See comment Line 211
Line 243: See comment Lines 220-226
Lines 250-345: Again, due to the lack of statistical power and microstructural observations, I suggest avoiding very strong statements (i.e. “MS addition also increased the efficiency of RTSF”, “This can be related…” or “The positive effect of a small volume of fibers can be credited to”, among others) and replacing them with expressions such as "it seems", “this could be related…”, “a possible explanation…”, “it may be…”. This comment can be applied to the full Results and Discussions section.
Fig. 12(b): In my opinion, this type of graph has little value without a strong statistical support to determine a significant maximum. I suggest its removal.
Conclusions: Same comment as before. Avoid strong statements and promote the use of sentences such as “it was observed”, it seems” or “noticeable”
Author Response
Reviewer# 3 (CHANGES ARE MARKED GREEN)
In my opinion, the work presented can be published with some minor changes. The testing methods are appropriate for determining the most relevant properties (mechanical properties, durability), and a considerable effort has been made that is worth publishing. However, as a general rule, I believe that the number of samples is not sufficient to draw statistically significant conclusions, nor has a hypothesis test has been conducted, so the study presented falls within the category of a pilot experiment, valid from a qualitative point of view and still very interesting for other researchers, but insufficient to draw significant conclusions from a quantitative point of view. Also, techniques for characterizing the microstructure of the tested mixtures have not been employed, which again prevents establishing certain types of conclusions. Consequently, the use of very definitive expressions pointing to quantitative effects should be avoided and replaced with conditional expressions more suitable for the type of experiment carried out.
Just as a suggestion, and without the acceptance of the article depending on it, I would like to recommend a recent work on the use of recycled fibers, in case the authors consider it appropriate to include it in their state-of-the-art review: Residual strength and drying behavior of concrete reinforced with recycled steel fiber from tires, Revuelta, D., Carballosa, P., García Calvo, J.L., Pedrosa, F., Materials, 2021, 14(20), 6111
I include more specific comments below.
Response: I am thankful for the time you took to review my paper. Your feedback was immensely valuable, and it significantly improved the quality of my work. Your perceptive remarks showcase your proficiency and dedication, and I am sincerely grateful for them. The recommended study is highly relevant to the scope of this work and has been included in the literature review.
Comment 1: Line 71: “impact toughness” instead of “impact the toughness”.
Response (L71): Thank you for this correction.
Comment 2: Lines 112-114: Where do these properties data of MS come from? Have they been obtained through tests? If so, please cite the test methods. If not, clarify that they come from the technical datasheet.
Response: These properties of MS came with a technical datasheet provided by the supplier.
Comment 3: Line 123, Table 1: Please cite the test methods used to determine these properties.
Response (L130-133): The references have been cited in the 2.1.2 section.
Comment 4: Lines 188-197: How many samples have you used for the determination of these properties? Three, as for the mechanical properties? Please, specify.
Response (L191-193): These lines have been revised to further increase the clarity.
Comment 5: Figure 4: If you have used three samples for the determination of density, please add deviation bars as in Fig. 5.
Response (See Fig. 5): Complied.
Comment 6: Line 211: In my opinion, since you don’t perform any statistical hypothesis testing and with the number of samples used per batch (3 in some properties, others to be clarified if only one has been used), the experiment does not have enough statistical power to use the terms "significant" or "not significant". Although the conclusions are still interesting from a qualitative point of view, I suggest eliminating the use of such terms (significant/not significant) in the text, as it may lead to a misinterpretation by suggesting that the results are statistically significant. Perhaps the word “noticeable” could be a better choice.
Response: We have replaced the word ‘significant’ with ‘noticeable’ throughout the paper.
Comment 7: Lines 220-226: Since you don’t have microstructural observations on your own samples to support these statements, I suggest the use of the conditional form (could be).
Response: Thank you for this suggestion. We have revised the discussion of the results.
Comment 8: Line 242: See comment Line 211.
Response: Complied.
Comment 9: Line 243: See comment Lines 220-226
Response: Complied.
Comment 10: Lines 250-345: Again, due to the lack of statistical power and microstructural observations, I suggest avoiding very strong statements (i.e. “MS addition also increased the efficiency of RTSF”, “This can be related…” or “The positive effect of a small volume of fibers can be credited to”, among others) and replacing them with expressions such as "it seems", “this could be related…”, “a possible explanation…”, “it may be…”. This comment can be applied to the full Results and Discussions section.
Response: Thank you for these valuable suggestions. We have revised the discussion of the results to avoid strong statements.
Comment 11: Fig. 12(b): In my opinion, this type of graph has little value without a strong statistical support to determine a significant maximum. I suggest its removal.
Response: We have removed the correlation charts and discussion considering the comments from Reviewer 2 and Reviewer 3.
Comment 12: Conclusions: Same comment as before. Avoid strong statements and promote the use of sentences such as “it was observed”, it seems” or “noticeable”.
Response: We have revised the conclusions to avoid strong statements. Thank you so much for your insights, we have also learned a lot through the revision process considering constructive feedback from reviewer 3.
Round 2
Reviewer 1 Report
- The results in the paper might be more discussed by the relevant literature.
Author Response
Reviewer 1
The results in the paper might be more discussed by the relevant literature.
Response: We are again thankful for the efforts and invaluable time of Reviewer 1 for reviewing the revised version. We have highlighted the revised discussion of the results in the context of the literature.
See highlighted lines (in BLUE)
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Reviewer 2 Report
can be accpeted
Author Response
We are grateful to the reviewer for accepting the changes in the revised manuscript.
Round 3
Reviewer 1 Report
The authors have made the necessary changes. Therefore the manuscript can be accepted.
