Refractory Concrete Properties—A Review

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper is rather superficial and not very accurate in its drafting. English language needs revision for grammar and syntax. Below are some general and specific, even if not exhaustive, comments. I hope they can be useful for review.

General comments:

The Introduction is repetitive, and it does not sufficiently highlight the importance of writing this review paper.

Section 2. Materials used in refractory concrete: 1) the authors repeatedly talk about the use of cement substituting materials in refractory concrete.  In accordance with what reported in the abstract, it would be more appropriate talking about “materials replacing Portland cement”. Furthermore, the meaning of standard, medium and high type for CASs (line 77), should be specified. 2) Alag is among the materials listed as possible aggregates for refractory concrete (line 80). This is a synthetic material for which at least the meaning of the name should be provided.

Section 3. Properties of the refractory concrete: 1) Comparisons between physical and mechanical properties of mixes prepared with Portland cement or CAC and, presumably, the same aggregate are presented in paraph 3.1; comparisons between properties of mixes prepared with natural or refractory aggregates are in paragraph 3.2. No result is presented and/or discussed about the effects of binders other than CACs on concrete mixes. 2) Despite the relatively high number of references cited in the manuscript, only few citations are in the above paragraphs, mainly between [21] and [27]. Also, citations of references [35], [66] and [67] are available. To provide the readers a better understanding of the completeness of the analysis and the significance of the results presented, addition of a table before paragraph 3.1.1 is suggested. The table should summarize the various physical/mechanical properties measured and the type of mix investigated in the literature, along with the relevant references. Criteria adopted to select the results for comparisons should also be described.

Section 5. Conclusions: this section is erroneously numbered as 5, instead of 4. Furthermore, it should be rewritten pointing out the major findings of the work, but avoiding to provide numerical values without general validity (e. g., slump, compressive strength, etc., which are strongly dependent from materials characteristics, mix composition, and curing conditions). The final comments about the need of future work on innovative materials would require a previous paragraph where the limits of refractory materials currently used are highlighted.

Some specific remarks:

 

Lines 34-35: References [1] and [2] appear to be poorly relevant to the concrete use and production. More appropriate references could be the following: [1] Monteiro, P., Miller, S. & Horvath, A. Towards sustainable concrete. Nature Mater 16, 698–699 (2017). https://doi.org/10.1038/nmat4930 (These authors affirm: “Except for water, concrete is the most consumed material in the world by mass”.)   [2]  Joao M. Uratani, Steve Griffiths, A forward looking perspective on the cement and concrete industry: Implications of growth and development in the Global South, Energy Research & Social Science, 97 (2023) 102972.  https://doi.org/10.1016/j.erss.2023.102972 (These authors state: “Thus, as cement and concrete continue to be among the most consumed industrial products worldwide ….”)

Line 36: Revise the statement concerning the main components of concrete as follows: "... at least two types of aggregates including fine and coarse, ....". This is because  more than two aggregates may be combined to obtain a satisfactory particles grading.

Lines 98-100: Revise the statements. Two different diagrams including calcium aluminates with silica or iron oxide are presented in Figure 3 and Figure 4, respectively.

Lines 124-125: I think the contents of oxide components are expressed as wt.%. Please add units to the values reported in the text.

Line 130: The heading of paragraph 2.2.2 is the same as of 2.2.1. Please check.

Line 137: The density values should be provided along with appropriate units.

Table 1: Check the chemical composition of CAC reported from reference [8].

Paragraph 3.1.1 and Table 7: Different studies are recalled in the text (line 164). However, only two references are cited. According to the reference list, citations [24] and [25] seem to be exchanged. Please check.

Line 175: replace “both mix” with “both mixes”; replace “in its values” with “in their values”.

Line 232: Given the structure of the sentence, its second part (“however, the mixes containing calcium aluminate cement record lower values”) is implicit and may be omitted.

Line 239: Replace “Another two studies” with “Two other studies”.

Lines 240-245: The results of flexural strength presented in Figure 7 deserve further discussion. Indeed, the only significant strength increase at 300°C is observed for the results from reference [26].

Table 9: Express all the results with the same approximation (two decimal digits).

Paragraph. 3.1.5: The results in Figure 8 show an increase in tensile strength of CACC with respect to NC. Were similar results found also for compressive and flexural strengths? In this regard, no citation of reference [27] in paragraphs 3.1.3 and 3.1.4.

 

 

 

Comments on the Quality of English Language

Carefully check the whole text. Some suggestions for the revision are within the above specific remarks.

Author Response

Please see attached documents.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Conducting a literature review on Refractory Concrete Materials is undoubtedly a worthwhile endeavor. I found it engaging to examine the manuscript and appreciate the opportunity to review it. Here are some suggestions to enhance the manuscript's quality:

1. The author should elaborate on the process of searching, selecting, and finalizing the 65 papers included in the review.
2. Specify the research databases used for the paper search.
3. Clarify the keywords employed and the type of screening performed to select these papers.

Additionally, the paper's structure should be explained at the end of the introduction.

Author Response

Please see attached document.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The paper is good but still needs some improvements, as shown below:

Please revise the title and make it more appropriate to present the overall scope of the paper.

Please provide a significance of review and structure of the article at the end of the introduction. 

Figures 1,2,3, and 4 are blur. Please replace. 

In section 2, The text related to some of the Tables from Table 1 to Table 6 is too less. Please discuss in detail the summary of each table. 

Section 3 can still be improved as the compressive strength shown here are very limited, and more data are available in the literature. Please improve. For example https://www.sciencedirect.com/science/article/pii/S0950061823011820

Add a discussion section before conclusion and provide the application of CACC.

The conclusion needs to be re-written. Revise the conclusion based on the properties discussed in the paper. 

Add future work to the discussion.

Mention at least 10 points/directions for future work.

 

 

 

Comments on the Quality of English Language

Minor editing of English language required

Author Response

Please see attached document.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The revised manuscript has improved compared to the previous one. However, it is still not satisfactory for the English language and for some technical/scientific aspects.

In the latter regard, the addition of Table 7 to paragraph 3.1. summarizing the properties investigated for several mixes prepared with Portland cement or Calcium Aluminate Cement is appreciable. However, no information is provided about the composition of such mixes. In particular, the water-to-cement ratio should be reported, considering the well-known and great effect this parameter has on the properties of cementitious mixes. This information would give robustness to the comparisons presented in the rest of the work.

Another aspect requiring attention is that of phase diagrams. A check is necessary for Figure 6, where the solid phase sequence from left to right should be (C+C3A), (C3A+C12A7), (C12A7+CA), (CA+CA2), (CA2+CA6) instead of (C+C3A), (C3A+CA), (CA+C12A7), (CA+CA2), (CA2+CA6).

Below are reported some language remarks.

Line 194: Revise the sentence as suggested: “The binder most used to replace Portland cement in refractory concrete is CAC.” Here the definition of acronyms NC and CACC should also be provided at their first appearance in the text.

Line 277: the subject of the sentence (Gulec et al.) is plural, therefore, the verbal form “conducts” appears to be not correct.

Line 402: as for the previous comments check for singular or plural.

Lines 422-423: too repetitive. Revise as follows: “… as the immersion time increases from 7 to 63 days [23]”.

Line 680: replace “to be use” with “to be used”. A suggested rephrasing of the sentence is: “Using bio-ash materials with high alumina contents as calcium aluminate cement replacement.”

Line 684: replace “using of waste” with “using waste”.

Line 709: replace “that allows” with “that allow”.

 

Comments on the Quality of English Language

Revision is still necessary

Author Response

Please see attached document.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

Accept

Comments on the Quality of English Language

Minor editing of English language required

Author Response

The authors would like to thank the reviewer for the time he/she puts in revising the manuscript and for his/her valuable comments.

Thank you for the valuable comment. The English language has been checked throughout the whole manuscript.