Mechanism of Polyurethane Binder Curing Reaction and Evaluation of Polyurethane Mixture Properties

Round 1

Reviewer 1 Report

Comments:

The present work studies focus on analyzing the curing reaction mechanism of polyurethane (PU) binders and comprehensively evaluating the PU mixture’s properties. The authors studied some characterizations as Marshall specimen height test, Splitting tensile test, Rutting test, Low-temperature bending test, Freeze-thaw splitting test, Four-point bending fatigue test, and Fourier transforms infrared spectroscopy analysis. 
Although the article is well-structured and presents logically ordered and coherent topics, it is crucial to fix some typos and improve the english.
Below are my suggestions:
1) improve the introduction by inserting the importance and innovation of this work;
2) what is the importance and relevance of the material studied for the scientific community and industry? This point was not very clear!
3) Figures 1, 2, and 3 can be removed from the manuscript, as they have no relevance.
4) Materials and methodology should be improved, as the form of presentation is a little confusing.
5) the most critical point to be improved is the discussion.
6) The conclusion must be improved.
7) As the manuscript was presented, it does not offer innovation for the area.

Therefore, my suggestion is to reject the article in its present form, and after the necessary modifications, the work must be submitted for further re-evaluation.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

I have only some (minor comments), predominantly linked to the "FT-IR" part:

• I suggest that you use the term band instead of the term "peak" (I think band is more common expression when IR spectra are discussed
• I miss references for assignment of the bands to certain vibrations
• what do you mean by "hard area" and "soft area "Table 4". Rather unusual expression in the field of FTIR spectroscopy
• just a note: it is always hard to compare intensities of the bands - I guess you have not conducted the curing measurements in situ - because of the various amounts of substances measured. More reliable approach would be if you used a band that does not change with time as an internal standard and then compare an intensity of the band of interest with the intensity of the internal reference band 

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Preparation and properties of polyurethane composite materials for asphalt pavement were studied in the submitted manuscript.  It is interesting in the field of asphalt pavement.  My comments are as follows.
1. P3, L2: Concerning the materials, are these common name  PU 70# base asphalt and SBS modified asphalt in the world?
2. P3, L5: Is Qilu 70# common name in the world?
3. P3, L6-7: How about the molecular weight of PU binder?
4. P6, L9: What kind of isocyanate did use?
5. P6: Figure 1 is just a beaker with liquid.  It doesn't has important meaning.
6. P6, L15: What is the KBr coating method?  The PU binder was coated on KBr?

7. P7, L27: There are any crosslinkings?  I think linear polymer chains.

8. P13, 4. Conclusions: The numbers were repeated.

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

The authors conducted factorial experiment on curing of PU by means of binder. They varied different parameters, including the optimal time for curing and the formation of of the PU structure, for achieving optimal mechanical properties of PU mixture. Thus they achieved excellent splitting tensile results, freeze - thaw cycles. It appeared that the PU mixture has very low wear-ability and it is excellent candidate to replace the asphalt on the roads. The paper can ne accepted in its present form.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors answered all questions conveniently, and they made all suggested improvements. Thus, I am satisfied and accept the article in its current form.