Review Reports - Sargassum-Modified Asphalt: Effect of Particle Size on Its Physicochemical, Rheological, and Morphological Properties

Round 1

Reviewer 1 Report

This manuscript presents the effect of particle size on the physi-cochemical, rheological and morphological properties of sargassum-modified asphalt. The manuscript contains some interesting points. The reviewer thinks that the manuscript needs to be improved before it is published.

The authors need to mention how much sargassum is produced per year so that the readers can know how this material is accessible and useful.
For the particle size, there are two different sizes, 850um and 500um. The reviewer thinks that all individual particles cannot be the same size as 850um and 500um. Is this the average of the particles or the particles under each size? In either case, the authors should provide the figure of the particle size distribution of each size condition.
The experimental method section needs to be modified. Several methods do not have a purpose in the section. So, the authors need to add and/or modify the purpose of each method so that readers can know why that test was conducted in this study.

Comments for author File: Comments.pdf

Author Response

Authors deeply appreciate the and reviewers’ valuable comments on our manuscript (sustainability-1413492). We carefully revised our manuscript in accordance with the reviewers’ comments and attached this rebuttal letter to explain how our presently submitted manuscript was improved compared with the former one.

Here, we reply to the reviewers’ comments in a point by point manner.

REVIEWER 1: The authors need to mention how much sargassum is produced per year so that the readers can know how this material is accessible and useful.

ANSWER:

In attention to the reviewer’s observation, in addition to the information included about the sargassum arrivals to the Caribbean and Equatorial Atlantic that has reached up to 20 million tons, the monthly sargassum accumulation per kilometer in the Mexican coastline was added, which is estimated to be about 9726 m³ and 817 tonsmonth^-1km^-1, according to Marx et al., (2021). This additional information can be seen in lines 68-73.

REVIEWER 1: For the particle size, there are two different sizes, 850um and 500um. The reviewer thinks that all individual particles cannot be the same size as 850um and 500um. Is this the average of the particles or the particles under each size? In either case, the authors should provide the figure of the particle size distribution of each size condition.

ANSWER:

As the reviewer accurately suggests, the sargassum particles sizes of 850 μm and 500 μm correspond to maximum particle sizes since their processing implied using #20 and #35 ASTM certified mesh sieves. Therefore, corrections were made in order to properly express that both sargassum particle sizes are under 850 μm and 500 μm, respectively. Changes were made in lines 20-21, 25, 86-91, 97-98.

REVIEWER 1: The experimental method section needs to be modified. Several methods do not have a purpose in the section. So, the authors need to add and/or modify the purpose of each method so that readers can know why that test was conducted in this study.

ANSWER:

According to the reviewer’s observation, the purpose of elemental analysis, FTIR spectroscopy, XRD, conventional physical tests and rheology, that were missing in the previous version of the manuscript, were correspondingly described by mentioning the particular purpose of each technique. Changes can be seen in lines 132-133, 145-148, 155-157, 162-163, 177-178, 180-183.

Thank you very much for your time and your suggestions for improving the present manuscript.

On behalf of all authors,

Dr. José Luis Rivera-Armenta

Corresponding autor

Instituto Tecnológico de Ciudad Madero

Author Response File: Author Response.pdf

Reviewer 2 Report

The research presented in the manuscript concerns evaluates the properties of sargassum modified asphalt.The subject matter is within the scope of the journal The methodology is sufficiently well explained that someone else knowledgeable about the field could repeat the study. The work is well written but needs some adjustments.

Abstract:

Please underscore the scientific value added in the abstract. Add some of the most critical quantitative results to the Abstract.

Introduction:

The article concerns the use of the biomodifier while in the introduction this topic has not been discussed. The authors of the manustript must presents relevant research on bitumens modified with natural origin. Recommended literature in this field:

https://doi.org/10.1016/j.conbuildmat.2019.116957

https://doi.org/10.1016/j.conbuildmat.2020.121514

https://doi.org/10.1016/j.jclepro.2017.09.256.

Materials:

What bitumen was used in the tests, please provide the designation - penetration degree according to EN or PG according to AASHTO standard.

Table 2. Chemical composition and physical properties of pure asphalt should be transferred to item 2.1 Materials.

In what mixer was the asphalt with the modifier mixed? How was the temperature of 180 ° C kept constant for 90 minutes?

Evaluation methods:

2.3.5 Conventional physical tests - these are known and commonly used research methods, therefore the descriptions of these tests should be shortened

Results and discussion

Sargassum acts as a filler in asphalt. The authors should check whether the results will be similar after using a different filler, e.g. mineral. If no comparative tests have been performed, the test results should be found in the articles.

Author Response

Here, we reply to the reviewers’ comments in a point by point manner.

REVIEWER 2:

Abstract:

Please underscore the scientific value added in the abstract. Add some of the most critical quantitative results to the Abstract.

ANSWER:

In attention to the reviewer’s observation, the scientific value and some of the most critical quantitative results of our study were included in the abstract. Changes in the abstract can be observed in lines 19-31.

REVIEWER 2:

Introduction:

https://doi.org/10.1016/j.conbuildmat.2019.116957

https://doi.org/10.1016/j.conbuildmat.2020.121514

https://doi.org/10.1016/j.jclepro.2017.09.256

ANSWER:

Authors appreciate the suggestions of references exploring the topic of biomodification of asphalts. They were taken into consideration to add a paragraph explaining the role of biomodifiers in terms of their content of hydrophobic and hydrophilic functional groups. This modification can be seen in lines 54-63.

REVIEWER 2:

Materials:

What bitumen was used in the tests, please provide the designation - penetration degree according to EN or PG according to AASHTO standard.

Table 2. Chemical composition and physical properties of pure asphalt should be transferred to item 2.1 Materials.

In what mixer was the asphalt with the modifier mixed? How was the temperature of 180 ° C kept constant for 90 minutes?

ANSWER:

In response to the reviewer’s observation, the classification of the asphalt was added, according to the quality certificate provided by the supplier. The asphalt used in this study is an AC20 PG 64-22, as seen in line 108. The Table 2 was removed from the Results and Discussion and placed as the reviewer suggested, in section 2.1 Materials, as observed in lines 110-111, now as Table 1. Additionally, the features of the mechanical stirrer IKA RW16 and the heating device constructed for keeping uniform the temperature of the asphalt blends, were included in the present version of the manuscript, in lines 116-122.

REVIEWER 2:

Evaluation methods:

2.3.5 Conventional physical tests - these are known and commonly used research methods, therefore the descriptions of these tests should be shortened

ANSWER:

Authors totally agree with the reviewers point, therefore, the descriptions of the standard methods used for evaluating the conventional physical tests of the asphalt samples were shortened. The revised section can be observed in lines 160-178.

REVIEWER 2:

Results and discussion

Sargassum acts as a filler in asphalt. The authors should check whether the results will be similar after using a different filler, e.g., mineral. If no comparative tests have been performed, the test results should be found in the articles.

ANSWER:

In attention to the reviewer’s observation, the filling mechanism of sargassum particles was discussed and compared with literature (Kim & Buttlar 2010; Nciri, 2018), in terms of the penetration index of modified asphalts. For example, modifiers act filling the free volume of the binder, and inducing particle-particle and particle-asphalt interactions. This discussion can be observed in lines 425-432.

Thank you very much for your time and your suggestions for improving the present manuscript.

On behalf of all authors,

Dr. José Luis Rivera-Armenta

Corresponding autor

Instituto Tecnológico de Ciudad Madero

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The reviewer thinks that all comments are answered

Reviewer 2 Report

The subject matter is within the scope of the journal. The methodology is sufficiently well explained that someone else knowledgeable about the field could repeat the study. Each figure and table is necessary to the understanding of the conclusions. All elements of the manuscript relate logically to the study's statement of purpose. The manuscript have been improved.