Investigation of Nano-Silica Solution Flow through Cement Cracks
Round 1
Reviewer 1 Report
An Experimental Investigation of Nano Silica Solution Flow through Cement Cracks
The present work is highly competitive on the field of civil engineering and construction of various multi-storied buildings, and bridges. Authors have focused on the key points of cracks within the cement structures through silica nano solutions. However, several issues to be resolved by the authors before go into publication in Sustainability.
Key points to be answered:
1. Authors should expand the introduction part about present studies. It’s not clear about present studies of your research.
2. Figure 2 is not clear to understand, needs to be modified.
3. (Prepare the nano-silica solution: The 2.5%, 3.75%, and 5% nano-silica were prepared by diluting the 50 % original nano-silica solution (Figure 5). The viscosity of the solutions are 1.2 cp, 1.3 cp, and 1.4 cp, respectively.) Why the authors have studied using random concentrations of 2.5%, 3.75%, and 5 %, instead of 1, 2.5, 3.75, and 5%, respectively, need a suitable explanation.
4. Authors should provide the synthesis and analysis of SiO2 Nanoparticles such as Particles size, FE-SEM, XRD, FT-IR etc.
5. Experimental Results are well established, however, the data points in the graphs are not appropriate for the journal standards, redrawn Figure 6, Figure 7, and Figure 8.
The overall manuscript is poorly written on the establishment of research data. I often found typos in each sentence, and correct them. The images are of poor quality, many data points are not visible in the graphs. This research work is suitable for publication after a major review.
Author Response
Please see the attachment. Thank you
Author Response File: 
Author Response.pdf
Reviewer 2 Report
SUMMARY
The article submitted for review is devoted to a topical issue. It deals with issues related to the experimental study of the flow of a nanosilica solution through cement cracks. The relevance of the topic is beyond doubt, because cement cracks are one of the most common damage in oil and gas wells. Such cracks can reduce the strength of the cement, and all this leads to large losses in zone isolation and fluid leakage.
The authors proposed a promising solution to the problem, they considered the placement of nanoparticle gels in cracks, studied the behavior of such solutions in crack penetration, conducted experimental studies, processed the results mathematically and physically, determined the error of their results, and drew conclusions that can be an important starting point for future research.
Thus, their studies are interesting, have a high degree of scientific novelty and have practical significance. However, the study also has shortcomings, which are listed below.
COMMENTS
1. The abstract made by the authors is not entirely correct. I would like to understand the scientific problem more clearly. The appearance of cement cracks is a fairly well-known problem and has an applied character. If the authors believe that the novelty has a sufficiently high degree in terms of filling these cracks with nanosolutions, then perhaps this is how the scientific problem should be formulated. That is, the authors concentrated on the applied problem, although their research goes beyond the applied problem only, because they conducted an interesting study and processed the results.
2. Perhaps the authors added the word "experimental" in the title of the article in vain. Perhaps they should have called the article simply “Investigation of Nano Silica Solution Flow through Cement Cracks”, because they not only conducted experiments, but also processed their results and determined some dependencies that are already analytical and somewhat go beyond just experimental studies. That is, the authors slightly devalued their work. I would like to wish them to clarify the title because their study is broader than the title states. But this, of course, only says that the study is quite strong and interesting.
3. The authors did some literature review in the Introduction section and identified the background that preceded the study. On the positive side, it should be noted that the authors relied mainly on the sources of recent years, since nanomodification and nanosolutions are a rapidly developing field in science; this is the correct methodological approach. However, it should be noted a very small number of analyzed sources on the topic. Nano-solutions and their applications in the construction, oil and gas industries are a popular vector in science. The authors should have focused their attention on more analyzed sources. The Introduction section should be expanded, scientific novelty should be presented in a wider scope.
4. In addition, it is necessary to clearly formulate the purpose of the study, the tasks of the study and, based on this, a working hypothesis. Experimental studies are described quite well, I would like to wish the authors to provide photos in better quality and with a more detailed description, since section 2 looks like a kind of scientific protocol with a photo report. I would like to understand a clear rationale for the selected models, equipment and which of these devices are copyrighted, and which are taken from some approved copyright or regulatory methods. Unfortunately, there is very little information about this.
5. The experimental procedures in section 3 are presented in a strange way. Sections 3.1-3.6 are claimed by the authors, but they are only brief phrases. Authors should reconsider the structure of the article, or the submitted file is probably a work in progress. Section 3 raises serious questions for the reviewer, the authors need to work through this section.
6. The experimental data are presented well, but there are comments on Figures 9 and 10. The authors took only 4 points as points along the abscissa in the case of Figure 9, and only 3 points in the case of nanosilica concentration in Figure 10. Such graphs are very uninformative and represent a rather rough scientific result. The authors should clearly explain and justify the choice of such a small number of control points. The discussion presented by the authors is quite interesting. There are references and comparisons with the results of other authors, but I would like to strengthen the analytical part and see clearly formulated scientific postulates based on the results of the study. What new have the authors brought to science and how do their achievements surpass other authors or how do they compare with them? A piece of text about this should be added after Table 2.
7. I would like to strengthen the conclusions with a more clearly formulated scientific result and an indication of the prospects for the development of the study and its applied significance. The number of references presented in the References section is somewhat surprising. A study that touches on such a serious scientific problem cannot cover only 10 sources. The authors had to analyze at least 2-3 times more literary sources, because otherwise it would be impossible to talk about scientific novelty.
8. Thus, the study is quite interesting, relevant and new, but its presentation does not yet allow this study to be published in the Journal Sustainability. The authors should seriously work on the article, take into account all the comments of the reviewer and send it again for review.
Author Response
Please see the attachment. Thank you
Author Response File: Author Response.pdf
Reviewer 3 Report
Paper presents topical issue and is written in clear language. Introduction explain scope of the research, the entire text of the article is complete and updated. The bibliography is update and adequate related to the work. The conclusions are described in right way.
Author Response
We would like to thank you for taking your valuable time and effort to review our manuscript. We are deeply grateful for all your comments, which encourage us to conduct better research in the future.
Reviewer 4 Report
Abstract and introduction are well written. The entire paper is adequately organized. Conclusions are clear and adequate. The problem is actual, and needs to be investigated in a future.
The manuscript presents interesting research and appropriate for the Sustainability journal of MDPI.
Author Response
We would like to thank you for taking your valuable time and effort to review our manuscript. We are deeply grateful for all your comments, which encourage us to conduct better research in the future.
Reviewer 5 Report
First of all the paper should report the values of measurements according to the International standards and proper units, since it is supposed to be published in an international paper.
Are the nanoparticles added in weight of volume percentage? I guess it's weight but might be better to specify it. Also a previous solution were used, is the silica percentage for that solution known? Otherwise the real final percentage of silica might only be guessed.
Experimental procedure must be rewritten, as an example as a bullet list, not using sub-paragpraph numeration
Row 113 ,Table 1, Figure 9 needs the use of proper units.
The labels of Figures 6-7-8 overlaps and are quite unreadable.
It could be useful more details and clarifications of that stepped pattern in pressure loss. It has been expected a more gradual trend as gradually the various classes of porosity become saturated with nanoparticles which initially follow the path of least resistance (macro pores) and gradually up to those with more resistance or nano pores (however the diameters of the nano particles are not specified).
Figures 9 and 10 show substantially the same result and only figure 10 is described, but due to how the discussion is set up it is more intuitive to obtain the data supporting the thesis from figure 9.
Reading the article it seems like something is missing. The introduction is underdeveloped and relegates all the basic concepts to a series of initial references (as an example I haven't even understood the source of these silica nanoparticles in the extractive industry).
The paper seems like a written report than a scientific article. The use of sub-paragraph numbering is incorrect, poorly understandable graphics and missing labels of different sizes.
Overall it seems a bit sloppy paper and with almost no insight into why the mathematical model used does not seem to have worked. As an example, the effect of surface roughness or the interaction between nanoparticles (which could be seen as the effect of the decrease in pressure increases with increasing concentrations) are mentioned, but without going into depth or citing references as support.
Author Response
Please see the attachment. Thank you.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Review Report2
Dec26, 2022
An Experimental Investigation of Nano Silica Solution Flow through Cement Cracks
The present manuscript is looking updated and eligible for the publication in the Sustainability Journal, however, I have asked authors to provide the data of SiO2 Nano particles such as Particles size, FE-SEM, XRD, FT-IR etc. They have not provided the requested data. In this case, I have left the decision to the editor. Other than them, I satisfied with the present form of the manuscript.
The overall manuscript is well written on establishment of research data. This research work is suitable for publication after major review.
Regards,
Ravi Kumar Cheedarala,
Changwon National University,
S. Korea
Comments for author File: 
Comments.docx
Reviewer 2 Report
The article has been improved quite a bit. In this form, it may be published.
Reviewer 5 Report
It is confirmed, by the authors' own admission, that the work is a report for the US Department of Energy, with no claim to experiment, but only to test some practical solutions to the cracking issue. So the standards are different from those currently considered international, including the units of measurement, otherwise the changes to the paper can be considered acceptable.
