Utilization of Coal Combustion Residues as Supplementary Cementitious Materials for Sustainable Concrete
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe literature review section could be further strengthened. It is recommended to add reviews of relevant studies.
Regarding " 20% CBS on the 56th day showing the largest range", it is suggested that the authors provide more contextual information explaining why the largest variance occurred at this particular point in time.
Figure 8 illustrates the flexural strength of different concrete types, but it is recommended that the textual descriptions further clarify the specific values of each set of data so that the reader can better understand the results.
The references section needs to ensure that the literature cited is up-to-date with relevant research.
Author Response
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Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe introductory discussion regarding the carbon footprint of cement production appears to be somewhat imprecise. Xi et al. (2016) provide evidence that “a cumulative amount of 4.5 GtC has been sequestered in carbonating cement materials from 1930 to 2013, offsetting 43% of the COâ‚‚ emissions from cement production over the same period.”
Xi et al. (2016) Substantial global carbon uptake by cement carbonation. Nature Geoscience 9, 880-883.
Furthermore, Coal Combustion Residues (CCRs) are known to contain trace amounts of heavy metals, including lead (Pb) and mercury (Hg), which can pose serious environmental and health risks if not properly managed. Given these potential hazards, it would be valuable for the authors to discuss whether they have assessed the implications of heavy metal contamination in their study.
Another aspect that warrants clarification is the choice of a 20% replacement level in the study. What was the rationale behind selecting this specific percentage? Providing justification for this decision would enhance the credibility of the methodology and offer a clearer understanding of the study’s scope.
Finally, the conclusions section appears to be overly concise, lacking sufficient discussion of the broader implications of the findings.
Author Response
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Reviewer 3 Report
Comments and Suggestions for AuthorsThis manuscript evaluates the fresh and hardened properties of concrete using CBA and CBS as partial replacements for ordinary cement. Overall, it is well-organized and well-written. However, the paper could be improved by addressing the following comments:
- How were CBA and CBS pulverized?
- The replacement ratio is 20% by weight for both CBA and CBS. Why was this percentage selected? Are there any references on how the replacement ratio correlates with performance?
- Following comment 2, considering the specific gravity, could you clarify why weight percentage was used rather than volume percentage.
- CBS-concrete exhibits lower compressive and splitting tensile strength while demonstrating higher flexural strength at 90 days. This phenomenon may not be explained by pozzolanic reaction and delayed hydration. Are there any references showing similar results?
- RCPT results indicate that CO shows higher passed charges at 56 days of curing, which is abnormal. Additionally, how many parallel tests were conducted? The figure does not include error bars.
- The chloride penetration resistance can benefit from using high aluminum phases due to the increased formation of chloride-absorbable phases. As stated in related references: https://doi.org/10.1016/j.conbuildmat.2024.134928
- Table 5 -missing table borders
- The conclusion could be more specific. The first paragraph should summarize the scope and objectives of this research. The following paragraphs should present data-based conclusions. Finally, use one or two sentences to highlight the contribution of this research.
Author Response
Please refer to the attachment.
Author Response File: Author Response.pdf
