Sustainable Bitumen Modification Using Bio-Based Adhesion Promoters

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This study investigates bio-based adhesion promoters derived from rapeseed oil and fatty acids to enhance bitumen's adhesive, rheological, and aging properties. Results show these additives improve adhesion, rutting resistance, and inhibit oxidation, with FA-based additives showing greater rejuvenating effects. The following problems may help to improve the quality of the paper.

(1) In the introduction section, the advantages of bio-based additives were well reviewed, but the research gap and research motivation were not clearly pointed out. Also, the technical route needs to be briefly introduced in the end of introduction.

(2) Glass was used to evaluate the adhesion of bitumen by testing its adhesion to glass, what is the motivation of this test? Also, the properties of glass need to be stated.

(3) In Figure 8. the legend needs to be set in all three figures

(4) In the conclusion section, the serial numbers 1, 2, 3, … are suggested to be revised to (1), (2), (3), …

(5) The long-term thermal stability of bio-based additives is one of the main concerns of bio-modified bitumen; it is encouraged to add some discussion about this issue.

 

Author Response

Dear Reviewer,

Thank you very much for your valuable and constructive comments. We have carefully considered your suggestions and made the necessary revisions accordingly. All changes have been clearly highlighted in the revised manuscript for your convenience.

We appreciate your time and effort in reviewing our work.

Sincerely,
The Authors

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This study has certain significance and reference value, but there are some issues that need to be explained or revised. The specific modifications are summarized as follows:

1. The introduction should include more current research on biobased adhesive additives to introduce the research object and innovation points of this article.
2. The various paragraphs in the introduction require more logical connections, such as the third paragraph introducing water damage and the fifth paragraph introducing surfactants, but these parts of the content are relatively isolated. Meanwhile, it is suggested to add the research ideas and significance of this article at the end of the introduction.
3. Cationic surfactants are more favored in asphalt modification and adhesion enhancement. Is the material used in this article cationic surfactants？
4. Will the use of high temperature of 140℃ in the synthesis of bio based adhesive accelerators damage the raw materials？
5. The author conducted a rolling bottle test, but there is limited analysis in this section.
6. The title of this article does not quite match the research content, as its scope is too broad and its sustainability is not well reflected.
7. The first and second conclusions can be merged.
8. The grammar of this article still needs to be optimized to make it more academic, for example, the sixth point of the conclusion can remove "The findings confirm the potential of ".
9. Adhesion performance is the focus of this research. Did the authors analyze the use of an adhesion specific test? For example, a pulling test? The tests indicated do not necessarily capture adhesion.

Author Response

Dear Reviewer,

Thank you very much for your valuable and constructive comments. We have carefully considered your suggestions and made the necessary revisions accordingly. All changes have been clearly highlighted in the revised manuscript for your convenience.

We appreciate your time and effort in reviewing our work.

Sincerely,
The Authors

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This research presents the development of a sustainable additive for enhancing aggregate-bitumen adhesion, synthesized from rapeseed oil and polyethylene amine. The article is quite readable. However, for it to be publishable in the journal, here are some suggestions for improvement:

1. The abstract should be structured to include an introduction to the research context, the objective, methods, results, and conclusions. Please revise the current abstract accordingly.

2.At the end of the introduction, the research objectives should be clearly outlined, possibly by including a new, dedicated subsection.

3. Paragraph 2.2.3 appears redundant, as the physicochemical properties of bitumen have already been listed in Table 1. This paragraph should be removed.

4.The rationale for choosing 0.4% as the modification quantity for the bitumen needs to be substantiated. The authors should justify this selection, potentially by referencing scientific literature.

5.The methods section lacks a dedicated part detailing the RTFOT and TFOT aging procedures. This should be added.

6.Tables 1, 4, and 5 should include a separate column for the units of measurement for each test. Table 2 is unconventional and requires reformatting to meet standard scientific presentation guidelines.

Author Response

Dear Reviewer,

Thank you very much for your valuable and constructive comments. We have carefully considered your suggestions and made the necessary revisions accordingly. All changes have been clearly highlighted in the revised manuscript for your convenience.

We appreciate your time and effort in reviewing our work.

Sincerely,
The Authors

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

 

Valuable topic. Major concerns are related to the bitumen modification by using bio-based additives. The article focuses on the laboratory investigations (physicomechanical behaviour, rheological behaviour, FTIR spectroscopy) of a 70/100 bitumen modified with rapeseed oil and higher fatty acids and using polyethylene polyamine. The experimental program is wide and complete, and the approach is well described.

 

In the reviewer's opinion, the paper needs the following revisions:

 

GENERAL AND SPECIFIC COMMENTS:

 

1. Introduction – At the end of this section the objectives of this study should be presented. It is confusing after reading a good introduction where the state of art is well described, to present directly the materials used in this study, without knowing what the actual scope of this study is and which are the objectives of it.
2. Section 2.1. – Why was the 70/100 bitumen used? Why not a 50/70? It is commonly used in that region? Please give this information in the revised manuscript.
3. Section 2.1. Table 1 – Great amount of data but there is no discussion on the obtained results. I suppose that the aim of this table is to show that this type of bitumen respects the normative regulations and is good to be used for HMA’s. If this is right, why the penetration test was performed at 4 temperatures? Why were all these tests performed if the norms do not require them? I suggest the authors to present the obtained results in 2-3 phrases.
4. Section 2.2.2. – How was the 0.4 wt. % of AP established? Please give this information in the revised manuscript.
5. Section 2.2.3. – The title of this section is confusing…‘properties of bitumen’, of the modified bitumen, of the virgin bitumen, all of them??
6. The sequence of the first three subsections is confusing. Bio-based adhesion promotors > Bitumen modification > properties of bitumen (here is a reference to Table 1). Please revise.
7. Section 2.2.4 lines 129-130 – ‘..test was used to analyze the viscoelastic properties of bitumen’. Which bitumen? Virgin, modified?
8. Section 2.2.4 lines 130 – ‘ASTM D7175-23 [45]’. In the references, the 45^th reference is a scientific paper not the ASTM standard. Please revise.
9. Section 2.2.4 lines 130-131 – ‘by calculation the complex shear modulus’. Only the norm of the complex shear modulus can be calculated ǀG*ǀ. Please revise.
10. Section 2.2.4 lines 133 – How and why these 5 temperatures were chosen?
11. Rutting parameter G*/sin δ. The proper way is ǀG*ǀ/sin δ. Please revise in the whole manuscript.
12. Section 2.2.7 line 155 – ‘bitumen B1’. What is bitumen B1?
13. Section 2.2.7 line 157-158 – In this section the methods used in this study should be presented. Therefore, is not proper to present result in this section (example results from Figure 4). Please revise.
14. General comment Section 2 – In this section the materials and the methods should be presented. However, after reading this section it is not clear how many bitumens were tested and what tests were performed on these bitumens. In order to clarify these aspects, I suggest the authors to present in a figure or a table the tested binders and the experimental plan.
15. Fig.1 – Please insert a) and b) near to the figures.
16. Section 3.2.3 line 237 – ‘various mineral aggregates’. How many types of aggregates were uses? I suppose that 2 types of aggregates were considered. Please clarify.
17. Section 3.2.3. Two methods were used to evaluate the bitumen adhesion. Results are presented in Fig. 2 and 3. The discussion on the obtained results is missing. Are these results obtained from rolling bottle test coherent with those obtained in Fig 2?
18. Fig. 4 and 5 have the same caption. Please revise.
19. Section 3.2.4 lines 333-334 – ‘PG58…PG64’. How the authors found this result? The PG’s are established based on the high critical temperatures. In this paper this parameter was not evaluated. Please explain.
20. Fig. 6 – In the figure caption a), b), c) are missing. Also, there are two figures with b). Please revise.
21. Fig. 8 and 9 – In the figure caption a), b), c) are missing. Please revise.
22. General comment – In the paper two terms are used for the same material ‘bitumen’ and ‘binder’. Please use only one term.
23. Reference [53] – is a norm/standard/report? Please revise.

Author Response

Dear Reviewer,

Thank you very much for your valuable and constructive comments. We have carefully considered your suggestions and made the necessary revisions accordingly. All changes have been clearly highlighted in the revised manuscript for your convenience.

We appreciate your time and effort in reviewing our work.

Sincerely,
The Authors

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The reviewer is satisfied with the authors' responses.

Reviewer 2 Report

Comments and Suggestions for Authors

Thanks for addressing the comments. The quality of manuscript has improved highly.

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have successful improve the manuscript based on the reviewer's comments.

Reviewer 4 Report

Comments and Suggestions for Authors

No other comments.