Dear editors and reviewers,

We sincerely appreciate your letter and the reviewers' comments regarding our manuscript entitled "Material composition and constitutive model development of red mud-based filler for highway tunnel invert filling applications: A comprehensive study" (Manuscript Number: PONE-D-25-03386). These comments are invaluable and extremely helpful in revising and improving our manuscript, and they provide significant guidance for our research. We have carefully reviewed the comments and made corrections, which we hope will meet your approval.

The editor's and reviewers' comments are outlined below in italicized font, with specific concerns numbered. Our responses are provided in blue text, and the changes made to the manuscript are highlighted in yellow text. Specific changes in the responses are in bold text.

The following is the original email:

PONE-D-25-03386

Material composition and constitutive model development of red mud-based filler for highway tunnel invert filling applications: A comprehensive study

PLOS ONE

Dear Dr. Rao,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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Kind regards,

Fahd Saeed Alakbari, Ph.D.

Academic Editor

PLOS ONE

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Reviewers' comments:

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Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

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Reviewer #1: Yes

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Reviewer #1: Yes

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Reviewer #1: Yes

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Reviewer #1: Yes

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: comments given in atthed file

Let's give the sample specifications in a small table

Are the layer thicknesses different from the values in Figure 3? Explain...

Could it be that the rates of increase are mutually confused???

The explanation of the figure is prone to misunderstanding in this way, at least it will be better to understand if the values determined by the ratio are shown on the graph

Can you give the desired min max values in Code 23 in a table?

give the correlation coefficients to the curve fitting equations....

may be given regression corr coef for the models ?

Can you explain what effect groundwater will have on the RBMF fill in the tunnel?

Can we make an estimate of the RMBF recycling tonnes in tunnel design per km?

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Reviewer #1: Yes: Dr. Mesut TIĞDEMİR

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Journal Requirements:

When submitting your revision, we need you to address these additional requirements.

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at

https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and

https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

Reply:

Thank you for your valuable comment regarding the manuscript formatting. We have reviewed and revised the manuscript to fully comply with PLOS ONE's formatting requirements. Please see the revised manuscript.

2. Please note that PLOS ONE has specific guidelines on code sharing for submissions in which author-generated code underpins the findings in the manuscript. In these cases, we expect all author-generated code to be made available without restrictions upon publication of the work. Please review our guidelines at https://journals.plos.org/plosone/s/materials-and-software-sharing#loc-sharing-code and ensure that your code is shared in a way that follows best practice and facilitates reproducibility and reuse.

Reply:

Thank you for your comment regarding the sharing of author-generated code. We would like to clarify that our manuscript does not include any author-generated code underpinning the findings. The only reference to code in the manuscript pertains to the serial number field used for inserting references via a reference manager. As no code is involved in our work, we trust that this requirement does not apply to our submission.

At the same time, we think that the word "code" may cause ambiguity. After discussion, we decided to replace "code" with "specification", which can more accurately express the meaning of Chinese standards. Please see pages 6 and 9-10 of the revised manuscript.

The specific modifications are as follows:

“The compaction test was conducted following the Highway Geotechnical Test Specification (JTG 3430-2020) [60] to determine the maximum dry density and the optimum moisture content of the mixture. The mixture was prepared by the dry soil method, beginning with a moisture content of 18%, increasing by 2% increments. The mixture was thoroughly mixed and then tested after being sealed for 24 hours. The experiment consisted of 7 groups of tests, with a total of 35 specimens (Table 2). The test utilized the heavy II-2 compaction method, involving compaction in three layers.”

“The UCS test was conducted following the Test Specification for Stabilized Materials with Inorganic Binders for Highway Engineering (JTG E51-2009) [61]. The specimens were prepared based on the optimum moisture content. To account for compaction effects during construction, three compaction degrees of 90%, 93%, and 96% were selected. The specimens were formed using hydraulic molds and placed in a standard curing box (temperature 20±2°C, humidity above 95%) for 7 days and 28 days. Three specimens were prepared in each group, resulting in a total of 126 specimens (Table 3). The test instrument used was a YYW-11 unconfined pressure instrument, manufactured by Tianjin Gangyuan Testing Instrument Factory, with a loading rate of 3 mm/min.”

“At a composite modified material content of 30% and a compaction degree of 96%, the 28d unconfined compressive strength of MRM reaches 6.22 MPa, which is still lower than the 7.2 MPa compressive strength requirement for invert filling in the specification [20]. To address this, soil stabilizers were introduced, with resin polymer as the main component. In this study, two types of stabilizers, Tushengda (TSD) and Suzhou Luxing (SZLX), were used to mix with MRM containing 30% composite modified materials. As shown in Fig. 9, with the addition of 5-fold diluted TSD stabilizer, the 28d unconfined compressive strength of MRM reaches 7.37 MPa, which meets the requirements of the specification.”

3. In your Methods section, please provide additional information regarding the permits you obtained for the work. Please ensure you have included the full name of the authority that approved the field site access and, if no permits were required, a brief statement explaining why.

Reply:

Thank you for your comments on our fieldwork permit. We would like to clarify that material acquisition for this study was conducted at a red mud dump site in Qingzhen, Guiyang, Guizhou Province, and no special permit was required to enter the site. And no specific authorization is required to collect samples from the site.

It should be further explained that, because Editor Maidelyn R. Peregrin believed that Figure 4 might involve copyright issues during the technical review, although these two photos were taken by us personally on site, we decided to delete Fig.4 to avoid unnecessary disputes.

4. We note that the grant information you provided in the ‘Funding Information’ and ‘Financial Disclosure’ sections do not match.

When you resubmit, please ensure that you provide the correct grant numbers for the awards you received for your study in the ‘Funding Information’ section.

Reply:

Thank you for pointing out the inconsistency between the ‘Funding Information’ and ‘Financial Disclosure’ sections of our manuscript. We apologize for the oversight, which occurred when we were filling out the relevant content in the submission system. We will make the necessary corrections to ensure that both sections are consistent and accurately reflect the funding sources. The revised manuscript will include the corrected information when resubmitted.

5. Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

Reply:

Thank you for your comment regarding the reference list. We have carefully reviewed all the references cited in the manuscript to ensure that they are complete and accurate. In addition to making the necessary changes, we have also verified the status of each cited article to confirm that none of them have been retracted.

We can confirm that all ci

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