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Peer-Review Record

Evaluation of Alternative Home-Produced Concrete Strength with Economic Analysis

Sustainability 2020, 12(17), 6746; https://doi.org/10.3390/su12176746
Reviewer 1: Anonymous
Reviewer 2: Anonymous
Reviewer 3: Anonymous
Reviewer 4: Anonymous
Sustainability 2020, 12(17), 6746; https://doi.org/10.3390/su12176746
Received: 8 June 2020 / Revised: 14 August 2020 / Accepted: 18 August 2020 / Published: 20 August 2020
(This article belongs to the Special Issue Economic Feasibility for Sustainability)

Round 1

Reviewer 1 Report

Please see attachment.

Comments for author File: Comments.pdf

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

The reviewer has been reviewed many papers for different MDPI journals. The reviewer would like to have a very good reason to reject any paper. According to the reviewer’s opinion, this paper with the current form MUST BE REJECTED. It is very difficult to give comments for every paragraphs and sections. Nevertheless, I would like to give a second chance to the authors to read other papers in the same journal and RE-WRITE the whole paper again.

The methodology section is VERY LONG, and the results and discussion section is VERY SHORT. In other words, the reviewer cannot see any relevant information regarding the results and discussion section (the most important part of any paper). I believe, they missed this part (results and discussion section) due to some technical mistakes.

 

The reviewer can review the paper only after it will be completed by the authors.

Author Response

Reviewer 2  - Comment

The reviewer can review the paper only after it will be completed by the authors.

Response: The authors feel so sorry. We reorganized the paper and modified appropriately. We developed the paper per other reviewers’ comments.  Please see the revised version. Thank you!

 

 

Reviewer 3 Report

Dear Authors, please find my comments below:

1) To me, this paper seems more like a good student project and case study than a scientific research paper. First, using 2 different SCM and recycled aggregates, concrete mixtures were cast, cured, and tested. The goal was to achieve 2500 PSI strength. Its findings and conclusion are simple, known, and supported by analyzing single costs. 

2) The literature review does not refer to recent research on the topic of fly ash or wood ash valorization on concrete. There are many scientific papers and reviews published in the past few years on this topic (e.g. https://doi.org/10.1016/j.resconrec.2019.02.028). 

3) Citation of the references done incorrectly in the second half of the introduction chapter and in the literature review chapter.

4) Table 13 adds no new information to the manuscript.

5) Figure 2 shows 3 strength graphs in 3 different styles? why? The purpose of these graphs is not that we could compare them?  It's okay that excel can create several different charts, but a simple bar chart is okay to show the results with readable sized letters in it.

6) What are the standard deviation between the measured strengths of the samples? What is the characteristic strength of the tested materials? If the goal was to achieve 2500 PSI, why do you calculate the costs for a mixture which achieved 2450 PSI? What indicates this 2500 PSI (17,24 MPa) strength for a "home-project"? Is this the minimum requirement for concrete according to ASTM?

7) The weakest part of the paper is the cost analysis, which is now basically some prices from other publications and from the internet. You used one supplier's prices only, there is no price sensitivity analysis. Transportation of materials and any additional costs of casting concrete are not included. Cement, wood and fly ash comes from a publication from North Carolina, while the aggregates are from Connecticut (600 miles distance).

8) Also, the price of water is zero?! I don't think this is sustainable to think like that.

9) You basically made one set of experiments with recycled aggregates just to end up with a brief conclusion that can be done by comparing 3 prices from the internet (the price of coarse and fine aggregates vs. price of RCA). Nevertheless, there is no money-saving... however, in the sense of sustainability, there is maybe a good reason for using recycled materials...

10) Therefore, the conclusions are only valid for that brief period, and for that occasion, when someone buys the materials exactly from the same location (if it is possible). It is a fictional case study now, it gives very little significance to this project as scientific research. 

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 4 Report

Ms. Ref. No.:  sustainability-844827-peer-review-v1

 

Evaluation of Alternative Home-produced Concrete Strength with Economic Analysis

Reviewer comments:

SUMMARY

The manuscript deals with a investigation on the use of fly ash, wood ash and recycled aggregates in concrete. This is a topic that has been widely covered in the literature, and it is somehow limited in the analysis and application of these results.

MAIN IMPRESSIONS

This paper has an undeniable practical usefulness. However, from a scientific point of view, the following issues must be addressed: i) References regarding compressive strength of concretes made with coal and wood ashes should be added and discussed in deep; ii) Effect of the chemical composition, particle size distribution and specific surface should also be discussed taking into account the findings given in the literature; iii) Data of both ashes should be reported, i.e. they must be the experimental data of your ashes. You should not use data from the literature.

 

MORE DETAILED COMMENTS

Title: Do you mean in-situ concrete? “Home-produced Concrete” could be unclear.

Lines 5-8: More information is required.

Line 12: Do you mean ready-mix concrete?

Line 13: Do you mean in-situ concrete?

Line 30: Replace “granulated blast slag” with “granulated blast-furnace slag”.

Line 31: Siliceous fly ash does not develop great cementitious properties when mixed with water.  Please, provide references to support your statement.

Line 32: Please, provide more references to support that “Fly ash … can enhance the … , mechanical  properties,…”. According to Fig. 2, this is not true.

Line 102: “2. Literature Review” should be part of the introduction.

Line 138: Please, provide some references “…the production of which causes 7% of carbon dioxide emissions of the world”.

Line 151: Please, provide some references “…Annually about 63 million tons of fly ash is produced …”. In the world?

Line 166: Tables 1-4: Which types of ashes have you used in the concrete mix design?

Line 166: Please, discuss the effect of the different LOI between both types of ashes (fly ash and wood ash).

Line 166: Tables 1-4: Data in these tables must be the experimental data of your ashes. You should not use data from the literature.

Line 182: Tables from other authors should not be in “3. Materials”.

Line 211: Could you please explain that SO3: 3.0 max <3.3?

Line 212: Could you please explain that Na2Oequi: 0.6 max < 0.7?

Line 226: W/C Ratio = 0.75 is very high. Please, add the slump data to the table.

Line 314: The paper should discuss the reults.

Line 399: nut?

Lines 377-400: Conclusions should underline the novelty of the work.

References must follow the format:

  1. Author 1, A.B.; Author 2, C.D. Title of the article. Abbreviated Journal Name Year, Volume, page range.
  2. Author 1, A.; Author 2, B. Title of the chapter. In Book Title, 2nd ed.; Editor 1, A., Editor 2, B., Eds.; Publisher: Publisher Location, Country, 2007; Volume 3, pp. 154–196.
  3. Author 1, A.; Author 2, B. Book Title, 3rd ed.; Publisher: Publisher Location, Country, 2008; pp. 154–196.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Thank you for making the corrections. I'm not making any further comments.

Author Response

Thank you so much

Reviewer 2 Report

The reviewer may not sure whether the authors received the first part of the reviewer’s comment or not. Nevertheless, the reviewer would like to give them the last chance to SIGNIFICANTLY improve the results section and compare their results with the previous study.

First comment (The reviewer has been reviewed many papers for different MDPI journals. The reviewer would like to have a very good reason to reject any paper.  It is very difficult to give comments for every paragraphs and section. Nevertheless, I would like to give a second chance to the authors to read other papers in the same journal and RE-WRITE the whole paper again.

The methodology section is VERY LONG, and the results and discussion section is VERY SHORT. In other words, the reviewer cannot see any relevant information regarding the results and discussion section (the most important part of any paper). I believe, they missed this part (results and discussion section) due to some technical mistakes. The reviewer can review the paper only after it will be completed by the authors.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

The paper improved significantly, however, I still suggest improvements to publish:

1) I think sustainability can be measured, for instance LCA is a pretty good measure, comparing the GWP (or other LCA indicators) of regular concrete and concretes with recycled aggregates. It shows that probably home made concrete with recycled aggregates or fly and wood ash has lower GWP, therefore less harmful for the environment. This analysis is often done in papers published in Sustainability. 

2) I suggest to improve the cost analysis furthermore! Is it possible to gather 3-5 prices for the materials around USA (at least) and analyze that too? Most probably yes. Now, all the conclusion is just valid for Connecticut. That is not so useful for everyone else, than people live in New Haven, Connecticut, so basically only for the Authors. Therefore, I suggest to expand it to at least USA scale, select some different (3-5) location around USA (e.g. California, Texas, Michigan, Florida) and show that your conclusions are valid from the east coast to the west. It will give a clearer picture definitely, even without considering transportation, labor and tax, which could be very different in the mentioned states.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 4 Report

Line 138: An updated infromation (2016 ==> "Currently, cement production is considered as responsible for approximately 7.4% of the global carbon dioxide emission (2.9 Gtons in 2016)")is given in reference: Appl. Sci. 2020, 10(1), 339; https://doi.org/10.3390/app10010339

References must follow the format: Abbreviated Journal + cursive & year in bold.

  1. Author 1, A.B.; Author 2, C.D. Title of the article. Abbreviated Journal Name Year, Volume, page range.

Accepted in present form.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 3

Reviewer 2 Report

The manuscript can now be recommended for publication.

Author Response

Thank you so much.

I really appreciate it.

Reviewer 3 Report

Dear Authors, the paper improved significantly during the last revision, and I think it is now almost acceptable, only minor mistakes needs to be addressed, and few results can be discussed more in detail in the final manuscript:

1) Check the numbering of the references. E.g. Reference number 6 is missing or reference number 27 is cited in the paper as the reference containing LCA data for cement and aggregates but in the list of references, it is the ASTM standard for testing density and air content. Therefore, please check the list of references and the manuscript for errors!

2) Line 88-89 are empty. If you delete those empty lines, you could avoid that Table 3 breaks to two pages.

3) Editing of the text in Line 275 to 280 should be corrected. 

4) Table 10 last column, add ash after Wood, because now it says "Wood 25%" only. In Table 10, CO2 emission factors could be converted to lb CO2eq/lb as well, since all of the units are imperial in the paper. If the caption says the values are for 1 cubic yard, then you may give all the values for 1 cubic yard, so the CO2 emission factors could be concerted to lb CO2eq/cubic yard. You only need the density of the materials for the conversion. It is also interesting to compare GWP (CO2 emission factor) presented in lb CO2eq/lb. and lb CO2eq/cubic yard, since the materials have different densities). 

5) I think that the GWP (you call it CO2 emission factor, it is usually called global warming potential as well) of the materials should be discussed in the paper, e.g. the recycled aggregate has 25 times less GWP (kg eq. CO2/kg) than new aggregates, however, aggregates have 97% less GWP than cement according to their mass... so reducing cement content of the concrete is the most important thing to be sustainable and environmental friendly in the concrete industry. Now, you mention this in the paper (line 385), but without numbers... 

6) It is also very interesting, that Fly ash has almost 17 times higher GWP than Wood ash, yet the concrete produced using 30% Fly ash has lower total GWP, since less cement is required using Fly ash to produce similar strength! These also could be analysed in your paper in details. 

7) It is also an important result that according to Table 10, if you compare total embodied CO2 equivalent of the materials, RCA saves only ~1% CO2 emission compared to regular concrete, while Fly Ash saves more than 28,5% and Wood Ash saves almost 24,5%. I think, this result of yours should be included in the abstract and in the conclusions as well. 

Author Response

Please see the attachment

Author Response File: Author Response.pdf

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