Recycled Sand and Aggregates for Structural Concrete: Toward the Industrial Production of High-Quality Recycled Materials with Low Water Absorption
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsAfter going through the manuscript, some comments are given below:
- Title: it would be better to have the title reconsidered further in more details.
- Introduction: it is a little bit messy in logical, which should be revised further and be focusing on giving the research background, cases analyses of relevant studies, research gap, and the current study in order.
- Section 2: it is suggested having the contents reorganized for better presentations.
- Section 3 “Results and Interpretation” and Section 4 “Discussion” are strongly advised combined into one section, namely, “Results and Discussion” for being readable.
- L569: the sentence “The exact reason for this behavior is not known.” is not properly presented in scientific paper.
- L575-577: justify the sentence “The selective separation seems to be indeed effective in 575 removing the adhered cement paste so that the negative effect on concrete performance is 576 minimized.”.
- Conclusions: it needs refine the research results and make concluding remarks with some potential quantitative data. The research limitations and future outlook may be also considered following up the final conclusion.
- References: the format is not with the requirements.
- The writing structure is not well appropriate, which should be reorganized according to some good publications.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsFollowing a thorough assessment, it is evident that the manuscript requires significant revisions across various aspects. The current presentation of the paper exhibits several issues that necessitate attention from the authors.
I can see several grammatical errors, so you need to carefully review the paper to avoid any writing issues.
In the introduction section, It would be helpful to briefly discuss the current challenges in the concrete industry and highlight the importance of recycling materials using the mentioned studies as follows.
-Experimental investigation on the bond performance of sea sand coral concrete with FRP bar reinforcement for marine environments
- Exploring temperature-resilient recycled aggregate concrete with waste rubber: An experimental and multi-objective optimization analysis
- Recent developments on natural fiber concrete: A review of properties, sustainability, applications, barriers, and opportunities
The discussion should delve deeper into the implications of the findings. Address potential limitations of the study and compare your results with existing literature. Discuss the broader impact of using recycled materials in structural concrete beyond the specific compressive strength considerations.
Regarding Density and Water Absorption, Elaborate on the practical implications of the observed correlation between oven-dry density and water absorption for recycled sands (RS) and recycled aggregates (RA)
The R2 value of 0.89 suggests a strong correlation. Have you explored potential outliers or specific cases where this correlation breaks down?
What are the reasons behind the coarser and more scattered distribution observed in RS3 sands compared to RS1 and RS2? Are there specific factors in the production process that contribute to this variation?
In what ways does the particle shape change as the particle size increases, and how does this influence the interaction between recycled aggregates and cement paste?
Regarding the content of polycyclic aromatic hydrocarbons (PAH) in RA2 and RS2, what measures can be taken to mitigate the negative impact on concrete performance? Are there feasible methods for reducing PAH contamination during the recycling process?
How do the results of loose and compacted packing density tests correlate with the overall performance of recycled aggregates and sands in concrete?
Comments on the Quality of English LanguageModerate editing of the English language required
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsDear authors,
In this paper, the authors propose a very interesting topic that refers to recycled sand and aggregates for concrete with relatively good results. The test protocol is varied and the statistical analysis confirms a series of encouraging results.
As a weak elements
Correct the sentences where the impersonal verb tense is not written. (Ex ....).
In this paper we studied a large sample of RS and RA produced by the selective
The abstract can be improved, it is too short I think line 50 is a mistake [3, fig. 6.11 p.151]. - please fix it The introduction is too brief. For such a subject, sufficient bibliographic resources can be found to highlight the authors with major contributions to the topic addressed.
Please put fig 4 on the same page as the table caption.
Please include in the paper everything related to trials and tests. Ex - Tables A.4-A.8 in Appendix or Supplementary Materials, Table S.2.
Please rearrange this paragraph:
RA1 and RA2 have a grading close to the reference quartzite 5/8 mm, whereas 347 RA3 shows a coarser 348 and scattered distribution. The scatter is related to the different production pro- 349 cesses and process 350 settings of the selective separation. For a given process and process parameters, a 351 continuous and 352 reproducible PSD was obtained (data not presented).
I did not understand very clearly how the sphericity of the particles was determined.
Figure 5. Sphericity of RS (left) and RA (right) particles from dynamic image analysis (Camsizer) 367
for individual particle fractions (Xc min). Recycled materials are more spherical than the reference 368
crushed sand and aggregates.
The statistical analysis table 3 on what data was performed - I can not understood.
Why do you refer only to the relative resistance and why not to the normal one?
Why is the figure at the end of the paper not explained?
As a notable elements
The present paper is very topical, necessary and useful for all economic actors. This is due to two major problems that it solves, recycling from demolitions, reducing the amount of raw materials and implicitly reducing pollution.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsAlthough the authors made some revisions on the manuscript, I still keep saying that the authors should answer reviewers's comments and questions one by one with the revised sentences, instead of just documenting "The title has been extended" and some other smilar expressions. Those revisions unmarked in the answers are very hard to easily to catch up in the manuscript text. Moreover, the current version is still not meeting the normal writing format for journals including Sustainability. Therefore, I make my decision to major revision for further upgrading the quality of the manuscript.
Comments on the Quality of English LanguageThe English language should be much improved to a scientific level.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe responses supplied do not meet the expected standards, and the authors have not demonstrated a meticulous consideration of the comments provided. Regrettably, given these circumstances, it is not feasible to include the paper in the ongoing evaluation process.
Author Response
No comment.
Round 3
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors have addressed most of the comments proposed from latest review. It can be now proceeded to next step after some other journal's requirements.
