Investigation of the Wet and Thermal Conditions Effect on the Micro-Scale Characteristics of Interfacial Transition Zone of Porous Asphalt Mixture
Round 1
Reviewer 1 Report
Comments for author File: 
Comments.pdf
Author Response
Response to Reviewer 1 Comments
Point 1: The aim of the paper should be clear
Responding 1：Thank you for your suggestions. The aim of the paper is revealing environmental degradation mechanism of performance, and which was added in the revised manuscript.
Point 2: Add additional explanation about the methodology
Responding 2：Thank you for your suggestions. The methodology was explained in 2.2 and 2.3.
Point 3: The results should be more specific
Responding 3：Thank you for your suggestions. Some results were added in abstract.
Point 4: Add additional keywords
Responding 4：Thank you for your suggestions. “Micro-scale characteristics” was added as a keyword.
Point 5: The introduction contains many old references and many sentences without citations. It is good to cite these very recent and related papers in the introduction, literature and to support your discussion referring to these paper https://doi.org/10.1016/j.cscm.2022.e01720
Responding 5：Thank you for your suggestions. All the references are relevant to the research, and some recent references is added in the revised manuscript.
Point 6: The methodology should be supported by previous studies
Responding 6：Thank you for your suggestions. To support the methodology reference 13, 22 and 23 were cited.
Point 7: The discussion of the results should be deep and supported by related previous studies
Responding 7：Thank you for your suggestions. The reference 24 to 28 were cited to relate previous studies and explain the phenomenon deeply.
Point 8: The resolution of the Figures should be improved
Responding 8：Thank you for your suggestions. The size of the figures is reduced for typesetting, and the resolution of the original Figures is enough
Point 9: Rewrite this sentence to be more clear.
Responding 9：Sorry, we didn’t found the sign on the sentence.
Point 10: The conclusion points should be covering all results of the study. Rewrite the conclusion points to be more comprehensive
Responding 10：Thank you for your suggestions. Some sentences were added to make the conclusions be more comprehensive.
Author Response File: 
Author Response.docx
Reviewer 2 Report
This an interesting paper on the interfacial transition zone of porous asphalt mixture. Below please find some detailed comments:
- the title - wrong grammar and word addressed, e.g. should be as follows: wet ageing seems wrong, the properties are not microscopic but are examined on a micro scale under the microscope.
The following publications are worth citing in the context of the described phenomenon:
- Jan B. Król, Rawid Khan & Andrew C. Collop (2018) The study of the effect of internal structure on permeability of porous asphalt, Road Materials and Pavement Design, 19:4, 935-951, DOI: 10.1080/14680629.2017.1283355
- Sarah Asfour, Frédéric Bernardin & Evelyne Toussaint (2020) Experimental validation of 2D hydrothermal modelling of porous pavement for heating and solar energy retrieving applications, Road Materials and Pavement Design, 21:3, 666-682, DOI: 10.1080/14680629.2018.1525418
- Jing Hu, Zhendong Qian, Pengfei Liu, Dawei Wang & Markus Oeser (2020) Investigation on the permeability of porous asphalt concrete based on microstructure analysis, International Journal of Pavement Engineering, 21:13, 1683-1693, DOI: 10.1080/10298436.2018.1563785
- On page 2, subchapter 2.1, there is a wrong reference to Table 2, it should be Table 1.
- On page 2, subchapter 2.1, a mix of language, please change "technical indexes" & "Technical Indices" to "Technical properties", and please unify the other terms throughout the text.
- The title of subchapter 2.2. should go to the next page.
- Please explain the sample cutting process better. If we cut porous asphalt without first soaking it with resin, there is a risk of damaging the internal structure and tearing out the grains with the saw disc. Please describe in detail in the text how this difficulty was dealt with.
- Figure 5 is not referenced in the text, please add it.
- Subchapter 3. 2 and throughout the text, it is better to use the word "interface" instead of "boundary".
Author Response
Response to Reviewer 2 Comments
Point 1: the title - wrong grammar and word addressed, e.g. should be as follows: wet ageing seems wrong, the properties are not microscopic but are examined on a micro scale under the microscope.
Responding 1：We apologize for the inaccurate description in the initial title, and the re-written title is as follows ‘Investigation of the Wet and Thermal Conditions Effect on the Micro-scale Characteristics of Interfacial Transition Zone of Porous Asphalt Mixture’. (page 1, line 1-2)
Point 2: The following publications are worth citing in the context of the described phenomenon:
Jan B. Król, Rawid Khan & Andrew C. Collop (2018) The study of the effect of internal structure on permeability of porous asphalt, Road Materials and Pavement Design, 19:4, 935-951, DOI: 10.1080/14680629.2017.1283355
Sarah Asfour, Frédéric Bernardin & Evelyne Toussaint (2020) Experimental validation of 2D hydrothermal modelling of porous pavement for heating and solar energy retrieving applications, Road Materials and Pavement Design, 21:3, 666-682, DOI: 10.1080/14680629.2018.1525418
Jing Hu, Zhendong Qian, Pengfei Liu, Dawei Wang & Markus Oeser (2020) Investigation on the permeability of porous asphalt concrete based on microstructure analysis, International Journal of Pavement Engineering, 21:13, 1683-1693, DOI: 10.1080/10298436.2018.1563785
Responding 2: Thank you for your suggestions. These references were added like ‘Microstructure affect the macroscopic characteristics of PA [9-11].
Point 3: On page 2, subchapter 2.1, there is a wrong reference to Table 2, it should be Table 1.
Responding 3：We apologize for the error in the initial manuscript. The error has been rectified in the revised manuscript.
Point 4: On page 2, subchapter 2.1, a mix of language, please change "technical indexes" & "Technical Indices" to "Technical properties", and please unify the other terms throughout the text.
Responding 4：We apologize for the errors in the initial manuscript. The "technical indexes" & "Technical Indices" have been change to "Technical properties" in the revised manuscript.
Point 5: The title of subchapter 2.2. should go to the next page.
Responding 5: Thank you for your suggestions. It has been revised according to your suggestion.
Point 6: Please explain the sample cutting process better. If we cut porous asphalt without first soaking it with resin, there is a risk of damaging the internal structure and tearing out the grains with the saw disc. Please describe in detail in the text how this difficulty was dealt with.
Responding 6：Thank you for your suggestions. Low temperature condition was used to reduce the effect of cutting on the internal structure. The following sentence was added in the revised manuscript: “To reduce the effect of cutting on the internal structure, the sample was cured in low temperature condition at -20 oC for 24h before cutting.”
Point 7: Figure 5 is not referenced in the text, please add it.
Responding 7: Thank you for your suggestions. It has been revised according to your suggestion.
Point 8: Subchapter 3. 2 and throughout the text, it is better to use the word "interface" instead of "boundary".
Responding 8:Thank you for your suggestions. It has been revised according to your suggestion.
Reviewer 3 Report
In the manuscript, the authors report an investigation of the effects of aging and water on the microscopic characteristics of the interfacial transition zone of a porous asphalt mixture. The paper is generally well-written and well-presented. However, it needs a polishment before being considered for publication. Following are some comments and suggestions:
The authors state in the introduction, “However, compared with dense-graded PA mixture.” PA? would that be another kind of mixture, since it says dense-graded? Is it not contradictory (dense x porous)?
In the first sentence of the last paragraph of the introduction, the authors mention a few studies. They should cite them.
The authors need to state the research objective in the introduction clearly.
Figure 1: the authors need to mention each part of the procedures (a, b, c, d, e). The same must be referred to in the text.
Figure 5: not mentioned in the text.
Paragraph after Figure 6: did research with other asphalt mixtures state the same?
Results (in general): the authors should compare their results with that of other researchers who did similar work. The reader must know if the trends observed are reported in the literature for different kinds of mixtures or if they are only valid for PA mixtures due to their high voids content (or other reasons that the authors should try to explain).
Figure 8: the colors do not help the reader. The same microcracks as the water bath sample are seen in the long-term aging sample. No?
The authors often use the term erode/erosion to refer to the effect of the water on the asphalt. Is it the correct term?
Please rewrite the first paragraph after Figure 9.
Based on all results, how would the studied factors affect the macroscopic characteristics of the PA mixture?
Conclusions: what about the main contribution of the work? The authors should also include some recommendations for further research. For instance, assess the macroscopic characteristics of such mixtures and compare them with the micro ones. Furthermore, investigate the interaction between aging and water effects.
Author Response
Response to Reviewer 3 Comments
Point 1: The authors state in the introduction, “However, compared with dense-graded PA mixture.” PA? would that be another kind of mixture, since it says dense-graded? Is it not contradictory (dense x porous)?
Responding 1：Sorry for the inconvenience from the error information. “PA” was deleted in the revised manuscript.
Point 2: In the first sentence of the last paragraph of the introduction, the authors mention a few studies. They should cite them.
Responding 2：Thank you for your suggestions. Although there are some studies on the interfacial transition zone of asphalt concrete mixture, but the author didn’t found the study on the effect of themal and wet conditions on the interfacial transition zone of PA.
Point 3: The authors need to state the research objective in the introduction clearly.
Responding 3：Thank you for your suggestions. The objective was added in the revised manuscript “The main objective of this study is to investigation of the wet and thermal conditions effect on the micro-scale characteristics of ITZ of porous asphalt mixture.”
Point 4: Figure 1: the authors need to mention each part of the procedures (a, b, c, d, e). The same must be referred to in the text.
Responding 4：Thank you for your suggestions. Each part of the procedures is numbered in the Figure 1, and which were referred in the text.
Point 5: Figure 5: not mentioned in the text.
Responding 5：Sorry for the inconvenience from the missing information. Figure 5 was mentioned in the revised manuscript.
Point 6: Paragraph after Figure 6: did research with other asphalt mixtures state the same?
Responding 6：Figure 6 just as an example to indicate the equivalent modulus map near the ITZ, the difference of modulus between the different asphalt mixtures is compared in Figure 7.
Point 7: Results (in general): the authors should compare their results with that of other researchers who did similar work. The reader must know if the trends observed are reported in the literature for different kinds of mixtures or if they are only valid for PA mixtures due to their high voids content (or other reasons that the authors should try to explain).
Responding 7：Thank you for your suggestions. As described in introduction, some researches have characterize the interfacial transition zone of asphalt concrete mixture, but our study mainly focus on the effect of themal and wet conditions on the interfacial transition zone, the related results and the reasons were given in 2.1 and 2.2.
Point 8: Figure 8: the colors do not help the reader. The same microcracks as the water bath sample are seen in the long-term aging sample. No?
Responding 8：Thank you for your suggestions. A little microcracks can be seen in the long-term aging sample photo, mainly because of the volatilization of light components reduces the lubricity of asphalt, and the microcracks of the water bath sample is more obvious, so the sentence is added in the revised manuscript “the volatilization of light components reduces the lubricity of asphalt, which leads to a little microcracks can be seen in the ITZ”.
Point 9: The authors often use the term erode/erosion to refer to the effect of the water on the asphalt. Is it the correct term?
Responding 9: Thank you for your suggestions. The effect of the water on the asphalt was referred use the term damage in the revised manuscript.
Point 10: Please rewrite the first paragraph after Figure 9.
Responding 10：Thank you for your suggestions. The paragraph was rewrite as “The line scan is carried out to obtain the thickness of ITZ according to the changes in the number of elements.” in the revised manuscript.
Point 11: Based on all results, how would the studied factors affect the macroscopic characteristics of the PA mixture?
Responding 11：In the paper, two factors were consider, including thermal condition and wet condition. The results indicated that under thermal condition the volatilization of light components reduces the lubricity of asphalt, which leaded to wrinkle phenomenon and rough surface. Under wet condition, the accumulation of water leads to the enhancement of the isolation effect of the water molecular film on the adhesion of the asphalt-aggregate.
Point 12: Conclusions: what about the main contribution of the work? The authors should also include some recommendations for further research. For instance, assess the macroscopic characteristics of such mixtures and compare them with the micro ones. Furthermore, investigate the interaction between aging and water effects.
Responding 12：Thank you for your suggestions. The following sentence is added in the revised manuscript: Noteworthy, the thermal and wet have obvious influence with modulus and morphology of ITZ, which have been assumed to be the reason for the stripping of PA. So, for future research, the relationship between the difference of ITZ and the micro properties, especially the durability of PA is required.
