A Coarse-Grained Molecular Model for Simulating Self-Healing of Bitumen

Round 1

Reviewer 1 Report

 

In the present paper, a coarse-grained model is developed for simulating self-healing of bitumen.

The topic is interesting and is within the scope of Applied Sciences.

I recommend publication of this paper after a revision in agreement with the following suggestions to the Authors:

1. The Authors should elaborate on verification of the CG model. Effective benchmark tests of the CG model should be performed, including equivalence between CG models and all-atom models on configurations, mechanical properties, glass transition temperature, etc., with emphasis on precision and efficiency of the CG models.  

2. Quality of figures must be improved.

3. The Authors must proof check their manuscript for some typos in the text.

 

 

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

In the present manuscript, the authors study and propose a coarse-grained model for Bitumen molecular dynamics simulation, which enables them to explore the long-time behavior of the structures. In this study, they investigated the diffusion coefficient as the main parameter to monitor the healing process of the bitumen. In addition, they measured the effect of temperature on the healing time.

Even though the concept of the manuscript is novel and the topic is of interest to the physical-chemistry community, there are severe drawbacks in how they presented the work. The paper’s readability is poor, and the manuscript lacks deeper analysis. Therefore, I recommend rejecting the manuscript or resubmitting it as a new manuscript after significant modifications. It would be good if the authors added discussions and provided details for the following:

(1)    Why do the authors use the COMPASS force field for their all-atom simulation and not the others? What are the benefits or priorities of this force field compared to the others?

(2)    What is the basis for selecting this composition for the studied system reported in Table 1?

(3)    In the all-atom molecular dynamics section, it’s better to explain temperature and pressure coupling and non-bonded and electrostatic conditions.

(4)    Quantum mechanics calculations are missing from the manuscript.

(5)    The box size is missing for the all-atom simulations.

(6)    Why don’t use these beads based on existing force fields? (Such as Martini and Elba)

(7)    Since the coarse-grained beads must be selected to maintain the structure's shape, how do you justify the coarse-graining of ring structures (e.g., in the form of hexagons)?

(8)    Was the all-atom trajectory used to simulate the coarse grain? The validity of the coarse-grained simulations must be checked based on the all-atom simulation, which is missing from the manuscript.

(9)    Due to the newness of this force field, it is better to consider Hydrogen atoms.

(10) How was the mass of the beads determined?

 

(11) Infigure 2, a legend including the color codes used for different bead types is necessary. 

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

It is necessary to involve a chemist in the work. There are many incorrect formulas and chemical names. For example, benzene has the formula C₆H₆ (table 3), compounds B5, B6, B7 (table 3) do not exist, methylthiophene is logically designated as S1 (in table 3 it is designated as a compound containing nitrogen N3). The symbols C₃Нn and С₄Нn (Table 3) are used when the amount of hydrogen in the molecule may differ. For known S/N ratios, it is customary to specify specific numbers. For example, benzene (Table 3, B1) must be specified as С₆Н₆. Authors often use the term "naphthene" incorrectly. Naphthenes are called cycloalkanes (for example, cyclohexane). There are no saturated aromatic hydrocarbons. Aromatic hydrocarbons must contain double bonds. And there are quite a lot of such imprecise terms.

The designation of the coloured "balls" is unclear (fig. 1 and 2). In fig. 2 in one case the aromatic ring is marked with one ball, in the other case (for aliphatic structures) only the carbon atom is marked with a one ball. This needs some explanation.

It is necessary to provide a list of abbreviations.

Row 172, in table 2. Calculation and reference values of properties of bitumen all- atom molecular model, contains only calculation and reference value but does not mention the laboratory experience of determining such properties.

It is not clear from the article why the properties of glass transition temperature was chosen for the all-atom molecular model but not of Fraas breaking point.

Conclusions are very similar to an abstract. Also, the practical application of the obtained research is not proposed in the conclusions

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Since the manuscript has been improved accordingly, I recommend publication in the present form.

Reviewer 2 Report

The authors have resolved my concerns in the current version and it can be accepted as it is.