Composition Optimization and Damping Performance Evaluation of Porous Asphalt Mixture Containing Recycled Crumb Rubber

Round 1

Reviewer 1 Report

The paper presents a research study aimed at optimizing the preparation process of high viscosity modified asphalts for porous pavement containing crumb rubber particles.

Recommendations are stated after several tests carried out to assess the influence of various parameters such as the rubber particle size and content, the asphalt-aggregate ratio, the mixture gradation, and the manufacturing temperature and timing. Laboratory trials were also performed to investigate the mix damping performance and the pavement structural capacity.

The research is well designed and described. The following list indicates small elements to be fixed before the publication.

1. Line 152: missing capital letter for point number (4).
2. Table 6: missing space for the “crumb rubber content(%)”.
3. Table 6: please, indicate the unit of measurement for the compaction times.
4. Table 7: use “Softening point (°C)” instead of “Softening point/°C”
5. Line 310: please, use the correct superscript for the power of 10.
6. Reference list: to uniform all references, please indicate the titles of contribution all with, or without, the capital letters (see the Journal template).
7. In general, it should be better to discuss about the repeatability of the obtained experimental results. Really, given the large amount of data, the numerical analysis of such aspect, or the representation of tests replicates (if available) could probably lead to confusion. However, the aspect should be at least mentioned in the text (please, discuss about the number of replicates and the test variability, just to objectivize the obtained results and the related outcomes).

Author Response

Authors Response

Dear reviewer,

Thank you very much for your valuable comments on our paper sustainability- 1613763 "Composition optimization and damping performance evaluation of porous asphalt mixture containing recycled crumb rubber". Your comments are really thoughtful and in-depth and I do honestly agree with most of them. The attachment is the revised manuscript. The main revisions in the paper and responses to your comments show as follows:

The paper presents a research study aimed at optimizing the preparation process of high viscosity modified asphalts for porous pavement containing crumb rubber particles. Recommendations are stated after several tests carried out to assess the influence of various parameters such as the rubber particle size and content, the asphalt-aggregate ratio, the mixture gradation, and the manufacturing temperature and timing. Laboratory trials were also performed to investigate the mix damping performance and the pavement structural capacity. The research is well designed and described. The following list indicates small elements to be fixed before the publication.

1. Line 152: missing capital letter for point number (4).

Authors: Thanks for your careful reviewing. The capital letter for point number (4) has been added. Please refer to Line 155 of the revised manuscript.

2. Table 6: missing space for the “crumb rubber content(%)”.

Authors: Thanks for your careful reviewing. The space has been added. Please refer to Table 6 of the revised manuscript.

3. Table 6: please, indicate the unit of measurement for the compaction times.

Authors: Thanks for your careful reviewing. The unit of measurement for the compaction times is indicated. Please refer to Table 6 of the revised manuscript.

4. Table 7: use “Softening point (°C)” instead of “Softening point/°C”

Authors: Thanks for your careful reviewing. The error in Table 7 has been corrected. Please refer to Table 7 of the revised manuscript.

5. Line 310: please, use the correct superscript for the power of 10.

Authors: Thanks for your careful reviewing. The superscript for the power of 10 7 has been corrected. Please refer to Line 318 of the revised manuscript.

6. Reference list: to uniform all references, please indicate the titles of contribution all with, or without, the capital letters (see the Journal template).

Authors: Thanks for your careful reviewing. The format of references has been checked and modified. Please refer to page 19 –21 of the revised manuscript.

7. In general, it should be better to discuss about the repeatability of the obtained experimental results. Really, given the large amount of data, the numerical analysis of such aspect, or the representation of tests replicates (if available) could probably lead to confusion. However, the aspect should be at least mentioned in the text (please, discuss about the number of replicates and the test variability, just to objectivize the obtained results and the related outcomes).

Authors: Thanks for your careful reviewing. The number of test replicates has been supplemented. Please refer to page 5 –6 of the revised manuscript.

Reviewer 2 Report

Refer to the attached PDF file for comments.

Comments for author File: Comments.pdf

Author Response

Dear reviewer,

Thank you very much for your valuable comments on our paper sustainability- 1613763 "Composition optimization and damping performance evaluation of porous asphalt mixture containing recycled crumb rubber". Your comments are really thoughtful and in-depth and I do honestly agree with most of them. The attachment is the revised manuscript. The main revisions in the paper and responses to your comments show as follows:

GENERAL COMMENTS

1) English language & grammar are very poor and need improvements throughout the paper. It is suggested the authors ask an "English Technical Expert"to scan thru the manuscript prior to resubmission for both English language & technical correctness.

Authors: Thanks for your careful reviewing. The language of the manuscript was thoroughly modified to enhance the readability. Please refer to the revised manuscript.

2) Formatting with some of the figures need be improved, particularly tags differentiating between figures (a), (b), (c), etc.

Authors: Thanks for your careful reviewing. Formatting of Figure 1 and Figures 3 –5 has been corrected and the titles of Figures 6 –10 has been modified. Please refer to the revised manuscript.

3) Format and spacing need to be improved, particularly ones between figures, tables, and section and sub-section headings.

Authors: Thanks for your careful reviewing. Format and spacing have been checked and improved. Please refer to the revised manuscript.

4) Recheck to ensure that all the Figures, Tables, Captions, and Equations are readable and consistent throughout the paper.

Authors: Thanks for your careful reviewing. All the Figures, Tables, and Captions have been checked and improved. Please refer to the revised manuscript.

9) The relevance of porous asphalt pavement (PAP) with the concept of sponge city construction should be briefly elaborated.

Authors: Thanks for your careful reviewing. The relevance of PAP with the concept of sponge city construction has been elaborated. Please refer to Line 51 –53 of the revised manuscript.

13) Page 3, Line 116: The reason for preparing high viscosity asphalt as opposed to other levels of viscosity needs to be included.

Authors: Thanks for your careful reviewing. The durability of PAP is mainly related to the embedded state and bonding state among aggregates. Compared with dense-graded asphalt mixture, PAP is more prominent by dynamic water scouring during service. Therefore, asphalt binder with excellent bonding performance is often used to prepare PSM. The reason for preparing high viscosity asphalt as opposed to other levels of viscosity has been added. Please refer to Line 115 –118 of the revised manuscript.

15) Page 4, Figure 1: The tags specified different particle sizes should be placed below their respective figures.

Authors: Thanks for your careful reviewing. The tags has been placed below their respective figures. Please refer to Figure 1 of the revised manuscript.

18) The line of graphs of different gradations need to be more visually diverse.

Authors: Thanks for your careful reviewing. Figure 2 has been redrawn to be more visually diverse. Please refer to Figure 2 of the revised manuscript.

20) Page 6, Table 6: The note should be presented with a smaller font.

Authors: Thanks for your careful reviewing. The font size of the note has been modified. Please refer to Line 207 –209 of the revised manuscript.

21) Line 142-203: For each test, the authors need to include and state in the manuscript the number of sample replicates prepared and tested per test method per variable per test condition.

Authors: Thanks for your careful reviewing. The number of test replicates has been supplemented. Please refer to Section 2.2 of the revised manuscript.

24) Page 8, Figure 3: The light red line that appears in all six figures should be defined.

Authors: Thanks for your careful reviewing. The light red line has been defined. Please refer to Figure 3 of the revised manuscript.

25) Page 10, Figure 6: The (a), (b) and (c) tags should be placed below their respective figures.

Authors: Thanks for your careful reviewing. The tags has been placed below their respective figures. Please refer to Figure 6 of the revised manuscript.

30) Page 14, Line 409: The definitions for “VV”, “VFA”, “FV” and “MS” should be included, as they are mentioned throughout Sub-section 3.4.

Authors: Thanks for your careful reviewing. The definitions for “VV”, “VFA”, “FV” and “MS” had been included in Section 2.2.4. Please refer to Line 202 –205 of the revised manuscript.

32) Page 14: The definitions for Factors A-I should be tabulated to help understand Figures 11- 15.

Authors: Thanks for your careful reviewing. The definitions for Factors A-I have been tabulated in Table 6. Please refer to Table 6 of the revised manuscript.

33) Page 15-16, Figures 11-15: The orange lines should be defined.

Authors: Thanks for your careful reviewing. The orange lines has been defined. Please refer to Page 15 –16 of the revised manuscript.

34) Add one to two sentences explicitly commenting on the practical applications & how the industry practitioners will benefit from the study findings.

Authors: Thanks for your careful reviewing. Comments on practical applications & how the industry practitioners will benefit from the research results have been supplemented. Please refer to Line 517 –518 of the revised manuscript.

35) Add one sentence explicitly commenting on the value & contributions of this study to the literature.

Authors: Thanks for your careful reviewing. Comments on the value & contributions of this study have been supplemented. Please refer to Line 517 –518 of the revised manuscript.

36) Add one sentence explicitly commenting on the limitations of the study findings.

Authors: Thanks for your careful reviewing. The limitations of the study findings have been added. Please refer to Line 549 –553 of the revised manuscript.

37) Recommendations for future studies may be included.

Authors: Thanks for your careful reviewing. Recommendations for future studies has been added. Please refer to Line 549–553 of the revised manuscript.

39) Update the reference list accordingly (refer to Comments # 7, 8, and 10)

Authors: Thanks for your careful reviewing. The reference list has been updated. Please refer to Page 19 –21 of the revised manuscript.

40) Check both the reference citation & listing format for consistency with the journal guidelines/requirements.

Authors: Thanks for your careful reviewing. The reference citation & listing format have been checked. Please refer to Page 19 –21 of the revised manuscript.

Comments #5, 6, 7, 8, 10, 11, 12, 14, 16, 17, 19, 22, 23, 26, 27, 28, 29, 31, 38 have been modified in the revised manuscript. Please refer to the revised manuscript.

Round 2

Reviewer 2 Report

Good job - The authors have addressed all of this Reviewer's comments.

The paper is acceptable for publication consideration.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.