New Coal Char-Based Building Products: Manufacturing, Engineering Performance, and Techno-Economic Analysis for the USA Market
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsPlease see enclosed, thank you.
Comments for author File: 
Comments.pdf
Please see enclosed, thank you.
Author Response
Thank you for the valuable comments and please find our response to comments in the attached file.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe author proposes replacing traditional building materials, such as stone, by coal char-based building products. The idea is relatively innovative, supports sustainable construction, and may be attractive to investors who accept a shorter service life of building materials and buildings.
In table 2, the average price per sq. m. was calculated at US$6.56. There is a small mistake. Should be US$64.63.
The economic analysis was made for the USA market. At the same time, the title of the manuscript contains no localization. It is recommended to precise the title: "New Coal Char-Based Building Products: Manufacturing, Engineering Performance, and Economic Analysis for the USA market".
Author Response
Thank you for the valuable comments, and please find our response to the comments in attached file.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe comprehensive study demonstrated the benefits of sustainable carbon-based stone veneers and thin bricks in terms of engineering performance and economic benefits. The tests and analysis presented and carried out according to the standard clearly show an improvement in product performance compared to the techniques used to date. The calculations carried out and the evaluation of the results obtained are correct and the conclusions are valid. It is correctly concluded that they offer a number of advantages over conventional products. The organisation and structure of the article is clear and logical, the published results are presented and analysed correctly, the figures are well developed and informative and show various characteristics. The article language is understandable, traceable, free of errors.
I have the following suggestions to raise the quality of the article:
Chapter 3 is followed by Chapter 5, needs improvement.
Error! Reference source not found error - report left in many places in the text, please delete: line 135,146, 158, 164, 172, 184, 192, 194, 196, 203, 207, 217, 218, 225, 227, 237, 238, 243, 250, 251, 263, 265, 286, 288, 312, 336, 401, 413, 455, 471, 533, 542, 554, 560, 561, 569, 606, 619, 646, 648, 665, 669, 670, 678
Line 160, Figure 2 in the numbering of the operations, after 11 comes 13
Line 394: in the text "...the ASTM requirement of 0.35 MPa" in Figure 15, the value according to ASTM 482 is 0.45 MPa, please clarify
Author Response
Thank you for the valuable comments and please find our response to comments in attached file.
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsDear Authors
It was with great pleasure that I reviewed your manuscript.
However, I have a few comments to make:
-You should update your references with more current ones.
-Throughout the text, the references are not in accordance with the Journal.
-The conclusions are very weak. They need to be more in-depth.
My Best Regards
Author Response
Thank you for the valuable comments, and please find our response to comments in attached file.
Author Response File: Author Response.pdf
Reviewer 5 Report
Comments and Suggestions for AuthorsThe manuscript shreds new insights into the usage of char-based materials, which hold promise to alleviate environmental concerns and energy consumption. Physical and mechanical properties are investigated; meanwhile, a techno-economic analysis is performed. The manuscript is well written and fits the scope of this journal, but there are some points to improve before further consideration.
(1) The introduction part emphasizes too much on known facts. The reviewer knows that the authors use coal char to make thin bricks and stone veneers, but they should make the uniqueness of this manuscript more clearly, i.e., what new findings or new methodology they have brought into the research communities?
(2) Page 2, Line 81: what are the differences between coal-derived materials and coal-derived char? In other words, why the authors discussed coal-derived materials if both groups of materials are equally good in replacing traditional fine aggregates or clay.
(3) A flowchart is suggested at the end of Section 1 that links different parts of this manuscript. The main methods or techniques can be helpfully annotated.
(4) Section 2: The authors did not present the micro/meso-structures of the char-based materials, which are important for potential readers; please explain this and refer to advanced techniques e.g. Computed Tomography (doi.org/10.1016/j.cemconcomp.2023.105270) and SEM. Different inner structures can determine distinct performances between char-based materials and traditional materials.
(5) It seems there is no Section 4? The authors should check this.
(6) Section 5: Adding fibres can also improve compressive strength, ductility and durability, see doi.org/10.1016/j.ijmecsci.2023.108270. The authors would benefit from discussing how fibres and char-based matrix can be integrated, so not only veneers but also structural members can be made for broader applications.
(7) The reviewer suggests the authors re-arrange the concluding part in a point-by-point manner, and only present the novelty and essential findings.
Author Response
Thank for the valuable comments and please find our response in the attached file.
Author Response File: Author Response.pdf
Reviewer 6 Report
Comments and Suggestions for AuthorsThis paper reviews technical specifications and economic metrics for char-based brick and stone veneers using appropriate ASTM standards and common corporate financial metrics.
Abstract - The manufacturing cost is compared to the average market price. While this shows opportunity for margin, it is equally important to understand the manufacturing cost of competitors' thin bricks and stone veneer. Market price is the value that the market will bear. The competitors' cost could be less than the cost of these products.
Line 45 - "will be slow" compared to what? Compared to other thin brick and stone veneer, compared to traditional brick and stone, compared to siding?
Line 50 - "for a longer period" compared to what?
Line 50 - "not demanding routine maintenance" What routine maintenance is done on brick and stone that would be different than these veneers?
Paragraph starting line 65 - The authors are pointing out weaknesses but do not compare those weaknesses against the coal char option. For example, the stone veneer using crushed aggregate uses a significant amount of energy. What does that mean? How much money for each? How much energy for each? Human resources are put into all processes. Coal is a natural resource just like stone is a natural resource. Sounds like this is exploiting one natural resource instead of exploiting another natural resource. What about strengths? The paper needs to directly and fairly show that the char product addresses these concerns. What if coal mining drops? This is about the chemical processing of coal to get char. Is this process using waste coal or mined coal specifically for this product? Transparency is needed on these topics.
Paragraph starting line 101 - The study needs to compare against existing alternatives and do so thoroughly and without bias.
Line 104 - There are 3 economic parameters, not 4.
Line 118 - What is the SP made of? How is it procured?
Line 135 and frequently throughout the paper (over 40 times) "Error! Reference source not found" is documented where figures/tables are called.
Line 138 - The word "aesthetics" might be a better word than "looks". Also it should be noted that some part of the wall might be load bearing and this needs to be included in the economic analysis.
Line 183 - The way this is written, it seems that the initial method is the rubber mold with texture and the second method is the steel mold, but the text here appears to have these flipped.
Line 271 - This seems to be section 4 not 5. Check numbering.
Paragraph starting 272 - Check the density numbers. 888.88 seems strange. Did you mean 889 kg/m3? From later in the paper at line 359, density impacts freeze/thaw cycles. There are good and bad things about density. Lower density isn't always favorable.
Line 303 - The calculation of 31.05% is confusing. How was this number calculated? I get 54.8% given the numbers presented in the paper.
Line 324 - Are commercial thin bricks treated? Could they be treated to address this issue? And then would they be any different? Conclusion stated in 327-329 is not convincing.
Line 335 - What is the saturation coefficient of competitors' stone veneers?
Line 358 - The density measure can be adjusted based on manufacturing process. Certainly the related density of the compressed product is related to the manufacturing process. Perhaps greater pressure is needed for the 27mm bricks.
Line 367 - Do you mean thickness or density? Also thicker are more difficult to make dense (line 355 ref 48)
Line 389 - "better" is not appropriate. There's no comparative data to make that claim.
Table 2 - Average price per sq m is $64.56, not $6.56
Starting line 483, consider making this a table and only explain in words any special considerations.
There's no mention of waste product costs.
Estimates of costs for existing competitive products are missing. Note that you would need to estimate costs for a different mix of inputs including labor if substantially different.
With 80% fixed cost, keeping the facility fully producing round the clock is important. But there are market limitations on how much you can sell (i.e. demand). The factory output needs to meet demand, whatever that might realistically be considering current players already in the market. Table 4 is based on the 1556.7 metric ton assumption. Some kind of reference is needed for % market capture to show that the assumption is in fact rational. Is 15 years to profitability rational?
Table 5 at line 573 mentioned 15% return rate. Did you mean 7%?
Line 599 - The assumption is that the factory is running full capacity. Might not be realistic.
Line 625 - A downside of natural stone was the claimed high labor cost? What is the comparison of labor costs between natural stone and stone veneer?
Paragraph starting 628 - Where is the pricing comparison for thin brick? What are the costs for disposal of waste product?
Paragraph starting 686 -NPV15 is noted 3 times in the this paragraph. Did you mean NPV7?
In summary, this is not an apples to apples comparison, as if in an attempt to hide the weaknesses of the product being documented. Fairly comparing the same competitive products across all specs is important. Just picking the competitive products that are not as good as this product for a certain spec is inappropriate. Said another way, the data for competitive products seem selective, as if only those examples which are not as good in a certain test are shared in this manuscript. How much market share is this product expecting to get given the players already in the market? What might happen to price over time?
Author Response
Thank you for the valuable comments, and please find our response in attache file.
Author Response File: Author Response.pdf
Round 2
Reviewer 4 Report
Comments and Suggestions for AuthorsDear Authors
I was very pleased to see that you have taken on board the suggestions for improvement that I gave you.
Thank you.
My Best Regards
Reviewer 5 Report
Comments and Suggestions for AuthorsThe reviewer appreciates that the authors have much improved the paper, which can be accepted for publication in the current form.
Reviewer 6 Report
Comments and Suggestions for AuthorsThis paper reviews technical specifications and economic metrics for char-based brick and stone veneers using appropriate ASTM standards and common corporate financial metrics.
The paper is significantly improved following the peer review process. In my copy, "Error! Reference source not found." is still showing up throughout the paper. This can be addressed in the editorial process to make sure that the correct figures and tables are called.
Comments on the Quality of English LanguageRemaining English language issues can be corrected in the editorial process. The errors are minor and will be caught in the proofing process.
