Assessment of New Bio-Cement Method for Sand Foundation Reinforcement
Round 1
Reviewer 1 Report
The authors have presented an interesting paper that deserves consideration by the journal. Only a few minor changes are indicated which the authors would be well advised to resolve.
Quantifiable data on the results obtained should be included in the abstract. Also, be careful with the subscripts of the chemical compounds; this error is maintained throughout the manuscript.
The introduction is correct and contains an appropriate number of references. Only, the sentence in lines 80-81 should be rephrased in terms of expected results, as otherwise they would be including conclusions in the objectives of the work.
In section 2.1.1. it would be convenient to indicate the chemical composition of the sands, perhaps an X-ray diffractogram is the most appropriate technique. Take it into consideration if possible in this work.
Has the granulometric curve been obtained in accordance with any standards, reference.
Figure 9, include error bars.
In general terms, the results are consistent and well described. However, it would be useful to discuss them on the basis of previous studies.
In the conclusions, it would be useful to include the limitations of the research and future lines of work.
Some parts of the Template have been deleted at the end of the manuscript: conflicts of interest, authors' contribution, etc. Correct.
No coments
Author Response
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Author Response.pdf
Reviewer 2 Report
This manuscript conducts a comparative study on the treatment effects of bio-cement infiltration method and bio-cement mixed method on sand foundation. While the work presents an interesting study, it requires a major revision before it is recommended for publication.
1. The title is not accurate enough. The research method involved is model testing rather than in-situ treatment.
2. There is a problem that technical terms are not accurate enough. For instance, "unlimited compressive strength" should be corrected to "unconfined compressive strength".
3. The research background and description of the research work in the Abstract should be adjusted appropriately. In other words, reduce the redundancy in the research background and provide a more detailed description of the research work carried out.
4. Abstract/Conclusions: why not any quantitative results? All over the qualitative interpretation? Provide some quantitative results here.
5. Introduction: The authors should compare to state-of-the-art researches in order to highlight the relative merits. Moreover, to benefit our readers and provide further narrative, researches of mechanical properties changes of soil treated with new solidification materials and solidification techniques other than the present topic should also be included in the 'Introduction' section. To this end, I would like to bring your attention to the following articles for your inclusion in the background to reinforce / echo the usefulness of your manuscript: (1) doi.org/10.1016/j.jobe.2023.106459. (2) doi.org/10.3390/ma15155114.
6. Materials and Methods: Why are different types and particle sizes of sand used in the reinforcement and the non-reinforced areas?
7. The quantified UCS test results did not appear in Section 3.1.1, which is inconsistent with the section title.
8. Section 3.2.4: “The bright area in the cemented particle diagram represented CaCO3 crystals, while the dark area represented the sand surface.” Please explain why this phenomenon appears and cite literature to prove it, if any. There is a problem of disordered layout in Figure 13. It is recommended to integrate multiple small images and annotations into a single image in advance.
9. Results and discussion: The discussion about how bio-cement method affects sand foundation solidified parameters combining all the experiment results is missing in this part. To provide further narrative regarding this behaviour to our readers, discussion to elaborate it is considered necessary. In other words, what is the underlying mechanism?
10. Authors used multiple methods to reinforce the sand foundation. The discussion of single experimental result is appropriate, but the manuscript lacks a comparative discussion of results related to different methods.
11. The language of the manuscript should be elaborated and revised carefully. It is of my opinion that there are some sentences that may be difficult for some readers to understand them. Meanwhile, English expression needs to be appropriately improved.
12.There are some details errors in the manuscript (lines 74; 218; 220), such as numerical errors in Figure 8, section number errors, inconsistency, etc.
English expression needs to be appropriately improved.
Author Response
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Reviewer 3 Report
Authors presented an article on enhancing the mechanical properties of sand through bio-cement method. The article is written well, however there are several major concerns, and those need to be addressed carefully prior to the acceptance of the article.
1. Authors should be careful about scientific writing. While writing CaCO3, "3" should be in subscript. Please correct throughout the manuscript.
2. Figure 4 not properly arranged. The (a) (b) (c) (d).. are not consistently organized.
3. Section 2.1.1 - it should be sandy soil or sand. "Sand soil" does not make sense, please correct.
4. I strongly recommend the authors to refer and cite few recent articles, which enhance the standard of this article. For example, as a milestone achievement, a field trial was attempted very recently - https://doi.org/10.1016/j.cscm.2023.e02086. Some other related works can be found as follows, 10.1016/j.conbuildmat.2021.122722, 0.1016/j.jenvman.2021.112315, etc.
5. In the abstract, it is mentioned that bio-cement infiltration method and bio-cement mixed method were studied. However, the discussion section doesn't significantly reflect the difference and benefits between the methods. This context must be extensively discussed.
6. Figure 11 compares the results with Cheng's results. Comparing only with one article's outcomes sometimes leads to error. I recommend to compare the UCS versus CaCO3 with other studies as well. Authors may refer https://doi.org/10.1016/j.sandf.2018.12.010 wherein many researchers' findings were compared. This will enhance the standard of this manuscript.
7. Though the bio-cement is often recommended, the technology has drawbacks as well. Particularly, release of ammonium ions is one major concern. I recommend this should be indicated somewhere in the discussion part. Authors can also highlight the possible approaches available in the literature to mitigate this drawback in MICP, such as precipitating as struvite, calcium phosphate bio-cement, ammonium-free MICP, etc.
8. How about the durability of the treated foundation? Consider the factors such as cyclic freeze-thaw, cyclic wet-dry, acid-rain. There are recent studies worked on these context, authors may refer and provide a brief discussion.
9. Legend is missing in Figure 3.
10. Figure 6 - those step 1 step 2 explanation can be put into the text, do not need to put in the Figure.
11. From the SEM images, it is understandable that both the spherical and rhombohedral crystals were formed. Did authors performed any XRD to confirm the polymorph?
Quality is fine, some minor check may be needed.
Author Response
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Round 2
Reviewer 2 Report
The citation format of reference [7] is incorrect, please modify it.
Author Response
Many thanks. The citation format of reference [7] has been modified as follow:
Su, Y.H.; Luo, B.; Luo, Z.D.; Xu, F.; Huang, H.; Long, Z.W.; Shen, C.P. Mechanical characteristics and solidification mechanism of slag/fly ash-based geopolymer and cement solidified organic clay: A comparative study. Journal of Building Engineering, 2023, 71: 106459.
Reviewer 3 Report
The authors have addressed all the comments. The article reached its acceptance.
Acceptable
Author Response
Thanks to the reviewer’s comments. The English has been polished.
