Study of High-Temperature Rheological Properties of Emulsified Asphalt Residues

Round 1

Reviewer 1 Report

Comments for author File: Comments.pdf

Moderate editing of English language required.

Author Response

Detailed response to the reviewer in attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript "coatings-2807378" by Wang et al. reported a Study of High-Temperature Rheological Properties of Emulsified Asphalt Residues. After review, this study is currently unpublishable. The authors have to make major changes. The authors should refer to the following comments to improve their work:

1. The term SBS which is abbreviated in the abstract, does not need to be repeated in the introduction, and it is sufficient to write the abbreviation form.

2. Review the results of several other studies in the introduction and explain the difference between this study and the from others.

3. Please provide images of the prepared samples (In the Test Materials and Methods section). Images give a better understanding to the reader.

4. In Figure 2, BA and SBSA are indistinguishable from each other—also EBA and ESBSA.

5. Section 3.1. This way of presenting explanations is not acceptable (in the form of points). This is a manuscript, not a PowerPoint for a presentation. Please rewrite these sections.

6. Section 3.2. This way of presenting explanations is not acceptable (in the form of points). This is a manuscript, not a PowerPoint for a presentation. Please rewrite these sections.

7. Section 3.3. This way of presenting explanations is not acceptable (in the form of points). This is a manuscript, not a PowerPoint for a presentation. Please rewrite these sections.

8. Generally, the Results and Discussion section needs a major revision. Unfortunately, there has been no discussion and it is only a data report. Please improve the discussion.

9. The language of the manuscript should be checked.

10. The number of references used is very limited. Please use the correct reference format. Please replace the up-to-date references.

Moderate editing of English language required.

Author Response

Detailed response to reviewer in attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

The article is about the analysis of the final state of emulsified asphalt, emphasizing the pivotal role played by the residue in asphalt mixtures. The topic is of interest, and of relevance for the scientific and industrial community. The authors conducted comprehensive dynamic shear rheological tests and fluorescence microscopy to explore the effects of emulsification and aging on the rheological properties and micro-morphology of emulsified asphalt residue. Through the analysis of results obtained from temperature sweep tests and stress creep recovery tests, the article highlights the diverse influences of asphalt emulsification on both the base asphalt and Styrene-Butadiene-Styrene (SBS) modified asphalt.

The article is schematic and well organised in the presentation of the results. However, the results provided have a very limited scientific relevance, being limited to a generic characterization of a specific sample under examination. For this limit the expected impact of this work is quite limited. In the current version the paper could be of interest of a very specified technical journal, while it could be considered for a scientific publication if further analysis and discussion are provided, with the aim to address some observation of wider interest. 

Further clarifications are necessary on some specific point. Below, I have listed a series of suggestions: 

·      Introduction: consider providing more background information and context to enhance the reader's understanding of the topic, of the research problem and its significance.

·      Test Materials: a better description of the components and emulsified asphalt preparation could be useful for ensure reproducibility and provide clarity to readers.

·      Test Methods: a description of the slide preparation and a clarification of the microscope used for the visualization of the internal structure of the asphalt is needed for a better comprehension and reproducibility.

·      Effect of Emulsification on the Viscoelasticity of Emulsified Asphalt Residues: in line 135-136 it is written that “…the physical action grinds the bitumen into micron-sized droplets disrupting the integrity of the common reticulation structure in SBS and causing changes in bitumen properties”, I would suggest running a more detailed analysis and discussion of this point and on properties affected. Also, there is alternating between 'asphalt' and 'bitumen' without clarification in SBS and ESBS data presentation.

·      Figures: there are no error bars, an estimation of experimental error should be added to prove the significance of the results obtained and their reproducibility

·      In rheological figurer G’ and G* are plotted vs temperature on a linear scale. I would suggest plotting G’ on a log scale, also to avoid strange dimensions (log(Pa)). What about estimating an Arrhenius activation energy from data fitting?

·      Rheological characterization is limited to measure of moduli at fixed frequency. Frequency and amplitude sweeps at some key temperatures should be provided, and discussed.

·      Microstructure of the emulsified fluid is poorly characterised. Only low magnification images are provided without any quantification of the structures observed. I would recommend adding high magnification images, improve the quality of the images by better aligning the condenser of the microscope to obtain a more uniform illumination, and quantify size and shape of the observed structures.

·      A relation between morphology and rheological response should be at least discussed qualitatively. Some models from literature could be used to provide also some quantitative analysis.

By addressing these suggestions, the authors can enhance the clarity of the results. A wider rheological characterization (frequency sweep) and a quantification of the morphology is in my opinion mandatory to increase the overall impact of the paper effectively showing some novelty.

Author Response

Detailed response to reviewer in attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

Referee comments on the paper by Houzhi Wang, Gang Xu, Chunxi Li, Yixin Zhou and Rui Wang “Study of High Temperature Rheological Properties of Emulsified Asphalt Residues” presented for publication in Coatings

 The work presents research on the rheological properties of asphalt mixtures, including the influence of emulsification on the residual properties of emulsified asphalt. Research on the properties of asphalt mixtures also contributes to improving safety, making the research topic interesting.

Four types of bitumen were tested: base asphalt (BA), emulsified base asphalt residue (EBAR), SBS asphalt (SBSA), and emulsified SBS asphalt residue (ESBSAR).

The work is well written, but I miss the discussion of the research results. The authors describe the research results in subsections without referring to or comparing their research results with similar results in the literature. Why and whether these tested asphalts are better than others. The literature analysis should be more thorough.

 I suggest a minor revision of the paper to improve its significance and clarity.

I have a few more comments below:

1.      Figure 1

BA, SBSA and EBA AND ESBSA have the same symbols on the charts. It is difficult to distinguish individual series. Please change it as in Figure 2.

2.      Figure 3

I suggest marking the drawings as a, b, c and d. Which drawings concern research before aging and which after aging.

3.      Line 165

Authors write:

“After ageing, the shear composite modulus of the asphalt and residue increases to varying degrees. This can be attributed to the volatilization of lighter components and the increase in asphaltene content during thermal-oxidative ageing. These factors lead to overall material hardening and an increase in modulus.”

On what basis do the authors claim that lighter components are oxidized (and what are these components) and the asphaltene content increases.

4.      There is no Figure 4, there is Figure 3 and then Figure 5

5.      In the captions of Figure 5 and Figure 6, please add what Figure 5a and Figure 5b, and 6a and 6b refer to.

With these corrections, the work will become suitable for publication in Coating

Author Response

Detailed response to reviewer in attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The paper can be published in present form.

Some minor revise should be done for checking typo grammer errors.

Reviewer 2 Report

Accept in present form.

Minor editing of English language required.