Rheological Deterioration of High Viscosity High Elasticity Asphalt (HVEA) Under the Coupling Effect UV Aging and Salt Freeze-Thaw (SFT) Cycles

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript examines the rheological properties of high-viscosity highly elastic asphalt (HVEA) exposed to ultraviolet radiation for aging and freeze-thaw cycles in a saline environment. Positive experimental results were obtained, which can be recommended for the use of this type of asphalt at sub-zero temperatures and for improving its properties after aging.
The following comments are made regarding the manuscript:
1. In subsection 2.2, the authors do not specify the composition of the asphalt samples being prepared, i.e., the amounts of added components are not specified: C5 resin, elastomer, furfural oil, and sulfur.
2. On page 9, the text initially lists the number of cycles as 8 (in two places); this should be corrected to 9.
3. In Figures 6 and 7, the authors indicate the required S value, which is 300 MPa, with a dotted line; however, the discussion does not compare this value of the studied samples with this value. 4. Also in Figures 8 and 9, the required m value of 0.3 is indicated by a dotted line. The discussion also does not compare the sample values ​​with this value.
5. In Section 3.5, the authors attribute the absorption bands at 2915 cm-1 and 2843 cm-1 in the IR spectrum to the symmetric and asymmetric stretching vibrations of methylene in aromatic compounds. I agree that these bands belong to methylene vibrations, but they are not part of aromatic compounds; they should be alkyl compounds or fragments.
6. In this section, it would also be more correct to write the characteristic peak of C=C bonds instead of the ethylene formula CH2=CH2.
7. Unfortunately, Figure 13 does not show a decrease in the intensity of the C=C bond peak at 966 cm-1.
8. On page 2, the abbreviation "nano-PA" should be expanded.

Author Response

Please see the attachment. Thank you~

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Title:

Rheological Deterioration of High Viscosity High Elasticity Asphalt (HVEA) under the Coupling Effect UV Aging and Salt Freeze-Thaw (SFT) Cycles

 

Abstract:

• “the S-value of HVEA decreased and then increased” – It is better to refer “S-value” as BBR Stiffness rather than S-value.
• “gradually decreased with the drop of VTS value”. What is the meaning of VTS?
• Please, be consistent with the abbreviation used: FT-IR or FTIR. Fix it in the entire manuscript.

 

Introduction:

• Please, be consistent with the terminology: high-viscosity high-elasticity asphalt OR high viscosity high elasticity asphalt? Fix it in the entire manuscript.
• “on the aging properties of SBS asphalt”. What is the definition of the SBS abbreviation?
• “3% of CB had significant adverse effects”. Please write the full word: Three percent of CB…. For formality.
• “the nano-PA modifier can effectively alleviate”. What is the meaning of PA abbreviation?
• “During the UV aging process, the PA modifier could enhance the viscoelasticity of asphalt and inhibit the generation of microcracks on the surface of asphalt. In addition, PA modifiers can promote the thermal stability of asphalt binders under UV irradiation, and can inhibit the generation of carbonyl and sulfoxide groups in asphalt.” Can you add any citation to support this? OR it’s related to this specific study/research?
• “de-icing salt solution and 20 FT cycles”. What is the meaning of FT?
• “Few studies had systematically examined the synergistic effects of simultaneous UV aging and SFT cycles on the rheological properties of HVEA, yet in real-world environments, these two degradation mechanisms often occurred simultaneously and may have synergistic effects that accelerate the deterioration of material properties.” Can you add any citation to support this? OR it’s related to this specific study/research?
• “bending beam rheology (BBR) test”… Please, changed to: “bending beam rheometer (BBR) test”.
• “(FT-IR)” or FTIR?

 

Materials and methods:

• “SK70#”. Please, change it to: “was a SK70# asphalt binder”.
• Table1 – Improve the labeling of this table. For example: “The main technical indicators of matrix asphalt binder SK70#”.
• Table1 – Make sure that in the entire manuscript the degree Celsius units are presented in the correct way. Use a space between the number and degree symbol all the time. For example: 25 °C and NOT 25°
• Table 1 – Index column change the column title. For example: “Required Index by standard”.
• “snow-melting agents, including NaCl and CaCl2, in concentrations of 3%, 6%, 9%, 12%”. Are these concentration by volume? By weight? By total binder? Etc. Please explain in the manuscript.
• Table 3 – Units of flash and pour point are not mentioned.
• Table 4 - Color Chromaticity has units? Or not?
• Table 4 – Motion viscosity units is unclear. 100 °C?
• “Subsequently, it was transferred to a heating mantle for heat preservation”. Heating mantle at what temperature? What is the volume used for mixing? 200 grams of base binder? 600 grams? Please, specify the volume of base binder used for mixing purposes.
• “A FT cycle process was set up for 18h”. What is the meaning of FT, SFT? Etc.
• “Thus, the number of SFT was set to 3, 9, and 15 times respectively”. Are these Times OR cycles? Please, be consistent with the terminology used.
• Figure 1 -Improve the labeling/title of this figure adding more information. Flowchart of what? Including what? Etc.
• Figure 1 – Meaning of TS? Write Stiffness instead of S only. Meaning of VTS? Was SK70# the Base binder?

 

Characterization:

• “The strain was fixed at 12% under the strain control mode”. What is the asphalt binder aging condition used for this test? You use 12% strain for unaged binder and 10% strain for short-term aged binder. Please, add the aging condition of the material tested. Include AASHTO reference
• In the temperature sweep test you did not explain the parameter G*/sind. Please add this information.
• Aging condition of BBR test? Include AASHTO reference
• “The fatigue factor G*·sinδ obtained from the TS test based on the DSR was used to evaluate the fatigue resistance characteristics of the samples.” What temperature and aging condition was used? Usually, this parameter is used for intermediate temperature. Authors cannot evaluate fatigue at high temperature from your temperature sweep test conducted above 52C. Include AASHTO reference
• Aging condition for FTIR used?

 

Results and discussion:

High temperature rheological properties:

• “when the UV-SFT number was 3 times”. Were these the number of cycles? The word times and cycles confuse the reader.
• Figure 2 and 3 – Adjust the z-axis units to kPa. Once again are these results related to unaged or short-term aged binders? Improve the label/title of these two figures. Add this information to them: “rutting factor results when UV-SFT was 9 times”.
• 3D Figures 2 and 3 are difficult to read. You can also try a 2D plot x-axis temperature, y-axis G*/sind, and different curves for different concentrations. Also, explain if short-term aging or unaged was used (cut-off value of 1.0kPa using 12% strain for unaged and cut-off value of 2.2kPa using 10% strain for short-term aged) The manuscript fails to explain this key testing information related to high temperature properties. This also apply to Figures 4 and 5. Show the cut-off value same as Figure 6.

 

Low temperature rheological properties:

• “As displayed in Figs. 6 to 9, As the test temperature decreased”. Do not use capital letter.
• Please, refer as “Stiffness” instead of S-value.
• Figure 6 and 7 – Improve the labeling. Write Stiffness instead of S. No abbreviations. It looks informal.

 

Temperature sensitivity:

• Figure 10 – Improve the colors of this figure. Almost, impossible to read. Also, improve the labeling. It looks informal.

 

Fatigue properties:

• Authors cannot conclude about fatigue testing at high temperatures.
• Figure 13 – Improve the colors. Difficult to read.

 

Conclusion:

• “resistance to deformation were relatively small at high temperatures and more pronounced at medium temperatures”. What was the intermediate temperature used in this study? It seems that no tests were conducted at intermediate temperature, but authors are concluding about intermediate temperatures.
• “As the test temperature increased, the fatigue factor of HVEA decreased gradually, which…”. The study cannot conclude something about fatigue resistance testing the material at high temperatures. Fatigue occurs at intermediate temperature. Authors cannot conclude about fatigue properties, because the material was tested at high temperatures.
• “fatigue resistance improved with the rise in temperature”… This is obvious, the viscoelastic material becomes soft and improving cracking.

- Major issues related to the testing methods (High temperature testing using unaged parameters (12% strain), fatigue tested at high temperatures). Please, explain in your manuscript why you took the decision of this.

Author Response

Please see the attachment!

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Dear authors you can find my review in the PDF file

Comments for author File: Comments.pdf

Author Response

Please see the  attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript presents a huge improvement over the previous version. Thanks to the authors to accomplish the reviewer edits and comments.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear authors

The necessary corrections and improvements noticed by my review report have been made successfully.