Structural Response of a Cement Concrete Pavement with a Buffer Layer to Temperature and Moving-Load Effects

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The study aims to establish the response model for a buffer layer from the multiple effects by temperature and moving loads. But overall research structure is confused which hinders the reviewer to follow the points. And the English language need carefully polish up before submission, even the first sentence in both Abstract and Introduction showed the evident grammar errors.

 

1.     What is the structure composition of the buffer layer? asphalt mixture or cement concrete?

2.     The title is the ‘…cement concrete…’, but the section of 2.2 appeared the analysis for asphalt mixture suddenly. And the following contents have not explained the objectives for this part.

3.     Line number please

Comments on the Quality of English Language

Must be improved

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This study appears to be a significant contribution to the field. Enhancing the clarity and depth of the above aspects could further strengthen the paper.

 

1. Could you elaborate on the specific innovative aspects of your study compared to existing research in the field?

2. Please provide a detailed description of how the lateral force was applied in your experiments.

3. The granulometric curve of the concrete is crucial for understanding the material properties. Can you provide more details or a graphical representation of this curve?

4. It is mentioned that Abaqus was used for the numerical model. Can you provide more details on how the model was set up and the specific features of Abaqus that were utilized?

5. In your model, was material non-linearity considered, particularly in the buffer layer, as well as in the concrete and soil components? How does the inclusion of these non-linear properties impact the results and conclusions drawn from your simulations?

Comments on the Quality of English Language

This study appears to be a significant contribution to the field. Enhancing the clarity and depth of the above aspects could further strengthen the paper.

 

1. Could you elaborate on the specific innovative aspects of your study compared to existing research in the field?

2. Please provide a detailed description of how the lateral force was applied in your experiments.

3. The granulometric curve of the concrete is crucial for understanding the material properties. Can you provide more details or a graphical representation of this curve?

4. It is mentioned that Abaqus was used for the numerical model. Can you provide more details on how the model was set up and the specific features of Abaqus that were utilized?

5. In your model, was material non-linearity considered, particularly in the buffer layer, as well as in the concrete and soil components? How does the inclusion of these non-linear properties impact the results and conclusions drawn from your simulations?

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

In this paper, a three-dimensional finite-element model of a cement concrete pavement structure with a buffer layer was developed to study the mechanical response of the structure under temperature and moving load conditions. At the same time, the comprehensive coefficient of the fatigue equation is modified according to the stress response of the concrete pavement under different vehicle speeds. The research content of the article is relatively sufficient. However, the structure of the paper needs to improve to be more organized and there are also errors in details, which need to be revised.

 

1. In the Introduction section it is mentioned that ‘scholars have recently proposed the inclusion of a buffer layer between the base layer and cement concrete pavement slab.’ But the references here were published many years ago.

2. There is an error in the units in Table 1.

3. The title ‘Filler’ in section 2.1.2 has nothing to do with the content of this section. Please check this.

4. There is no a in the failure formula of Mohr-Coulomb law at the end of Section 2.1.3. Please recheck this sentence.

5. In section 2, a lot of experimental data and analysis are contained, which makes the structure of the paper disorganized. These need to be revisited and reorganized.

6. In section 3.1, the change trend of the vertical deformation of the road center at low temperature is different in direction from that at medium and high temperature.

7. Is the range of the temperature-induced stress at the top of the pavement panel explicitly mentioned in the previous section?

8. It would be preferable to include a comparison with a cement concrete pavement without a buffer layer so that the function of the buffer layer can be demonstrated.

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The suggestions and comments can be found in the attached document.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 5 Report

Comments and Suggestions for Authors

The authors present a numerical analysis of the stress and deformation resulting in a concrete pavement layer under variable mechanical and thermal loading.  The topic is an important one with respect to road design.  As currently written, various issues exist in the manuscript that must be addressed:

1) What does, 'cement concrete pavement damage is mainly early damage' mean at the start of the abstract?

2) In the top paragraph of page 2, particularly, much of the literature review consists of stating that a certain study was performed, but not actually discussing the results of the study or how they pertain to the current work.

3) What does 'concerned' mean in the second line of the first full paragraph on page 2?

4) Additional explanation is required regarding the shear box.  Is the interface between the upper shear box and lower shear box aligned with the interface being tested?  As shown in Figure 2, the interfaces are typically not flat - how is the alignment with the testing apparatus determined?  What is the meaning of 'rpm' at the bottom of page 4?  How many tests for each condition were performed (and what are the resulting error/uncertainty bars on the data in Figures 4 and 5)?

5) In Equation 2, S should be A.

6) Just above the start of section 2.1.4, what is the meaning of, 'the friction coefficient tan(phi) is expressed by a'?  There is no 'a' in the following equation.

7) In Figure 4, the data should be presented on the vertical axis as shear force, not stress, since the force ratio is what is used to calculate the interlayer bonding coefficient. 

8) In the first full paragraph on page 6, the statement beginning, 'This is because' is not supported by data presented in the paper.  This statement could be explored by performing testing on samples created with different interface geometries.  However, it does not appear that work was done.  Much of this paragraph should be removed or should be restated as a hypothesis, not settled fact.

9) In Table 7, what are the units of the 'coefficient of heat expansion'?  This should typically be thermal expansion, not heat expansion.

10) At the top of page 10, in what order are the layers listed (4, 1, 2, 2, 3) - from top surface to bottom or vice versa?

11) In section 2.3.4 is the applied loading in the -y direction?  This should be specified according to the coordinate system displayed in Figure 9.

12) In Table 17, the reference used for the 'normative' calculations (26) should be noted in the column heading.  At what point in the assembly is this stress being calculated?  For what specific set of material properties and conditions is this being calculated?

13) In Figure 14 (and beyond), what is the reasoning for setting the bottom of the assembly to a temperature of 0C (based on the apparent asymptote of the data)?

14) When stresses are being presented, what stresses are these?  In the x-direction? y-direction? z-direction? effective stresses? Max value anywhere in the model? Values always at the same point of the model?  As presented, the stress values cannot be interpreted.

15) On page 17, do the authors have a hypothesis with regards to why the outer layer of the concrete goes into tension but the stress drops quickly to compression?

16) On page 18, how is it possible that, for the high and medium temperature conditions, 'the panel remains flat', when the numerical model has apparently been totally constrained (Table 17) - the result should be a convex deformed shape.

17) Near the top of page 19, the statement that the 'top of the surface layer remains subjected to compressive stress, and the stress value increases and then decreases' is not consistent with Figure 17.

18) Figures 18 (and following) should be presented in terms of time, not steps, to allow for easy correlation with data presented in Figures 17 (and following).

19) On page 21, the statement above Figure 22, 'compression deformation is completely restored after the vehicle leaves' is not consistent with the data presented in Figure 21.

20) On page 22, the statement in the second full paragraph with respect to comparing current results to those by Cai et al. is not consistent with the current work.  No results were presented for a case with no interlayer, so no conclusions can be made from the current results in this regard.  This section should be removed or restated.  The literature comparison is not justified as written.

21) Conclusion 2 states, 'warpage deformation of the pavement is most pronounced at high temperatures', seemingly at odds with 16), above.

22) Conclusion 3 - see 20), above.

23) Conclusion 4 is not based on any original work presented and is not supported by any additional calculations performed by the authors.  It should be removed or restated to make clear this is not a conclusion based on the current work.

Comments on the Quality of English Language

English word usage and grammar are generally ok.  A few questionable word choices and phrasings are identified above.  An additional grammatical review would be appropriate.

Author Response

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Author Response File: Author Response.pdf

Reviewer 6 Report

Comments and Suggestions for Authors

The paper presents research study analyzing structural response of a cement concrete pavement containing a buffer layer between the base layer and cement concrete pavement slab. Authors present interesting considerations focused on mechanical response of the structure under temperature and moving load conditions developing a three-dimensional finite-element model of a cement concrete pavement structure, providing analysis of the temperature fields, temperature-induced stress, and strain distributions in the structure under the cyclic temperature variations.

Although presented article may be interesting to the readers of Sustainability journal, the paper may only be considered for publication after the following concerns have been addressed successfully in a major revision:

1) At first, I found it very uncomfortable to point out errors in the text when the lines have not been numbered. It would make it much easier if they were.
2) Introduction of the "nomenclature" part is recommended because there are some variables, abbreviations and markings that should be defined at the beginning of the paper.
3) The Abstract part needs some improvement. In my opinion, an abstract should contain a summary of the entire manuscript and is intended to encourage the reader to read more deeply. The authors should provide more results here, rather than just presenting qualitative statements. Please provide some data here, or at least percentage results, confirming that a comparative analysis was carried out leading to specific conclusions. Moreover, in my opinion, the abstract should also be shortened a bit.
4) At the end of the introduction part I would like to see not only the plan of research (shown in Fig.1) but also a thesis stating what the authors would like to prove, show or obtain through the proposed research. Please start the last paragrah with: "The aim of this study is....".
5) Please avoid single-row tables (as in Table 1). In my opinion, table 1 can be combined with table 2. The same should be done with table 4 and subsequent ones.
6) Figure 2 contains two photos. In my opinion, the description should include a reference to both of them. It is advisable to provide the designation a) and b) along with an appropriate description.
7) Authors wrote: "...the specimens were placed in ovens set at controlled temperatures of 15, 30, and 60 °C for heat preservation." Please specify which samples were subjected to which temperatures. And if it comes to all of them, at what intervals, for how long, etc.
8) Please replace "The are shown in Figures 3." with "The arrangement of the test samples is shown in Figure 3" or something like that. Currently, paragraph 2.1.3. is written incomprehensibly and may be misleading. Please make it grammatically correct.
9) The notations in equations 1 and 2 do not correspond to their signatures below. Please pay attention to upper and lower case letters.
10) Authors wrote:"The ratio of shear force to vertical force is expressed as the interlayer bonding coefficient". Please provide it in the form of an equation, because at the moment it is difficult to say what the coefficient is.
11) In the paragraph 2.1.4 "Test result" please provide some more informations about the tests. How many test samples there were, how many times the tests were repeated, what were the standard deviations of the measurements, whether the values given in Fig. 4 and 5 are average values, etc.
12) Figure 6 is not mentioned in the manuscript text.
13) In the paragraph 2.2.1. "Uniaxial dynamic creep tests", again, please provide some more informations about the tests. How many test samples there were, how many times the tests were repeated, what were the standard deviations of the measurements, etc.
14) E1, E2, η1, and η2 should include subscripts in their notation. Additionally, explanations of individual variables in the equations should include a unit (please see eq. 3-5).
15) Authors wrote: "parameters E1, E2, η1, and η2 were determined, and the minimum correlation coefficient of the fitting result was 94%." Please provide detail informations about the measurement uncertainties.
16) The enlargements in Figure 15 (a) and (b) have no markings, only colors. Markings need to be added.
17) The markings on the enlarged graphs in Figure 16 are illegible.
18) Despite so many research results, the discussion of the results seems to be quite poor in analysis. Please add some more information about the percentage difference between individual results, add a collective table in which all the most important results are compared or a chart showing mutual correlations. In my opinion, repeating the results in Table 18 without comparing at least a percentage of the individual results is of little value.
19) The summary, in my opinion, also contains too few specific comparative results.  What is the significance of this manuscript in the context of the results obtained? The Authors also forgot to mention about what should be done next.

Comments on the Quality of English Language

Moderate editing of English language required. It's more about stylistic than grammatical issues.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

There is still some expression and format errors in the response letter.

Author Response

We apologise for the error in the response letter. Due to a very tight revision schedule, we were not able to edit the response letter very well. But our text has been revised by professional personnel and institutions.

Reviewer 6 Report

Comments and Suggestions for Authors

The manuscript looks much better after the improvements, although I regret to say that not all of my suggestions were taken into account. Nevertheless, I believe that even in its current form the article can be accepted for publication.

Author Response

We are very grateful for your suggestions for the paper, which is conducive to the better improvement of our paper.