Rheological, Spectroscopic, and Chemical Characterization of Asphalt Binders Modified with Phase Change Materials, Polymers, and Glass Powder
Round 1
Reviewer 1 Report
In this contribution, the authors investigated the effects of the phase change materials (PCM) and glass powder (GP) on the performance of asphalt binders. While this topic is inspiring to the readership of Appl. Sci., several critical discussions are overlooked. Therefore, the following questions and comments need to be addressed before making a further decision.
1. What is the chemical composition of the PCM? Why does mixing PCM with GP significantly change the TGA profile, other than the confinement effect of GP? At a ratio of 50:50, not all PCM is absorbed into the pores of GP (heterogeneous mixture in Line 351), but GPCM shows almost no weight loss below 125 °C, even for the non-absorbed portion of PCM. Besides, what are the weight loss profiles at other PCM to GP ratios? Similar questions in Figure 17, why does GPCM show no melting and crystallization peaks as observed in PCM? Does the confinement also inhibit the phase transition of PCM?
2. PCM is claimed to be confined in the pores of GP (Line 381). Are the pores in GP resulting from the packing of glass grains or the intrinsically porous structure (Line 147)? If the pores are from packing, when blending with asphalt changes the packing of GP, will PCM be released? Or, if GP grains are intrinsically porous, can the pore size distribution be characterized, e.g., using SEM or BET?
3. In Figure 2, why does adding 5% of PCM reduce the cohesiveness of asphalt binders so significantly? The pictures of the neat asphalt without PCM and asphalt with GPCM are expected for comparison. Also, does the PCM evaporate at the mixing temperature of 150 °C (Line 150)? Is the low cohesiveness due to the phase separation or foaming effect?
4. In Line 386, does 80% of PCM evaporate at 90 °C for 5% PCM, and all PCM evaporated at temperatures above 90 °C? If so, why is the PCM in 5% PCM more volatile than the neat PCM shown in Figure 12?
5. In Figure 13, 5% GPCM shows a higher viscosity than 7% GPCM, but 5% GPCM-SBS exhibits a lower viscosity than 7% GPCM-SBS. Why does SBS reverse the effects of GPCM on viscosity? Does the GPCM preferably interact with SBS more than asphalt?
6. In Figure 14, what is the contrast resulting from, the different electron densities in different phases or the roughness of the observed surface? How is the fibril microstructure formed? Why do the PCM and GP affect the width of fibrils?
7. In Figure 15, the baseline is not subtracted and peaks are not normalized before comparing the peak heights (Line 438). The curves are difficult to identify due to the color code and oversized width, the same as in Figure 18. The aromatic structures and sulfoxide need to be assigned to specific wavenumbers. Besides, for SBS, the peak at 700 (or commonly 699) cm-1 is typically assigned to the aromatic C-H deformation in polystyrene (Line 441), while polybutadiene shows a characteristic peak at 966 cm-1 for the trans-C-H wagging and torsion.
8. Other minor amendments:
Line 166, redundant thanks to.
line 268, G*/sinδ, the rutting index (Line 271), should not be denoted as the shear rate value.
Line 323, Table 4 instead of 3.
Line 387, the weight loss is due to evaporation instead of degradation at 150 °C. So is in Line 545 and 551.
Line 415, the control binder is shown in Figure 14 b-d instead of h-j. Figure 14 has a limited resolution, and the scale bars are illegible.
Line 459, two instead of tow main components.
Line 541, Figure 18 instead of 39.
Line 542, Figure 19 instead of 40. Figure 19 needs legends for all curves.
Showing pictures of instruments is not necessary.
Comments for author File: 
Comments.pdf
Author Response
Please see the attachment. The English language and style of the paper were reviewed and edited.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Overall good article and well organized. I have a few comments that must be incorporated before accepting.
1) No information on bia-based PCM is provided. It is necessary to know the source and detail (physical and chemical properties) of the used PCM in this article, to better understand its behavior compared to other PCM materials.
2) Detailed description of the used PCM must be provided in the materials section.
3) Line 195-196: Why time 2-3 minutes and a speed of 1000 rph was selected? provide valid justification.
4) Literature provided is not the latest. A sufficient number of related articles published in 2023, 2022, 2021, and 2020 must be provided.
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
Dear Authors,
Congratulations for the work done.
Manuscript applsci-2191202 investigates the effect of PCM, Polymer, and Glass Powder on Rheological, Spectroscopic, and Chemical Characterization of asphalt.
The subject of the article is very interesting and important in the field of modified asphalt. The research methodology is reasonable, the research is comprehensive and some very interesting and innovative conclusions are obtained. The results provide ideas for the subsequent modified.
In general, the structure and content of the manuscript is acceptable for Applied Science. Nevertheless, in order to improve its readability, please consider these recommendations listed below:
1、Table1 in 230min is likely to cause misunderstanding of the reader, should be ≥ 230, while the corresponding specification should be given.
2、Table2 does not use the prescribed format.
3、The phase change materials used in asphalt can be divided into high-temperature phase change materials and low-temperature phase change materials. High-temperature phase change materials can overcome the high temperature of asphalt concrete, low-temperature phase change materials have the effect of anti-condensation ice. The phase change temperature of the phase change material used determines its function, so the important parameters such as the phase change temperature of the bio-based phase change material used should be pointed out in detail.
Author Response
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Author Response File: Author Response.docx
Reviewer 4 Report
This study conducted tremendous experimental work to investigate the rheological, spectroscopic, and chemical characterization of asphalt binders modified with GP and PCM. It contains some innovative findings. However, the following some suggestinos are listed as followings:
1. Line 22, DSR, and TGA need an explanation in the abstract.
2. The introduction needs to be rewritten to improve the readability.
3. The authors need to examine the formation in this article. Such as Line 54, 150, 217, 262, 429.
4. Table 1 and Table 2 can be merged.
5. Figure 1 requires reformatting or adding a new table.
6. The format of the pictures and titles should be modified according to the template.
7. Add the type information of the testing instrument. Line 178, 246.
8. The numbering of the figures and tables need to be double checked.
9. Add references to support the author’s view. Line 299-534.
10. Figure 19, data point symbols should be smaller to avoid data overlap.
Author Response
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Author Response File: Author Response.docx
Reviewer 5 Report
applsci-2191202:
Follow my comments:
*The topic is current.
*Lines 1-3: The title is appropriate.
*Lines 9-15: The abstract is adequate as it contains all the elements: brief introduction; main goal; method; main findings; and conclusion.
*Lines 26-27: Do not use acronyms as keywords.
*Lines 29-35: Nanomaterials are also used.
https://doi.org/10.1016/j.ijfatigue.2022.107440
https://doi.org/10.1016/j.conbuildmat.2022.128087
*Lines 111-112: Review this sentence: “From the author’s point of view, there is no previous published data found to provide comprehensive insight on incorporating these additives in asphalt binders.” I disagree with the authors.
Clearly present at the end of the introduction the contribution of the paper to the area of knowledge.
*Lines 122-127: Justify the choice of ligands and inform the standards used in their characterization Table 1 and 2).
*Line 132: Justify the %.
*Discuss about Figure 1
*Improve the quality of Figure 1; and, present the characterization data of figure 1 in the text. Report all standards.
*Lines 144-172: Justify the percentages used;
*Lines 190-199: Justify the parameters used in the preparation (time, temperature, RPH). Justify the choice of proportions? Is it based on existing studies?
*In table 3, justify the proportion of additives.
*Lines 217-223: Inform the spindle used and the standard.
*Lines 224-237: Does this process have a standard? If not, inform studies that also performed this procedure.
*Equipment figures are unnecessary. Inform in the text the brand and model of the equipment used, as well as the city and country of manufacture.
*In the inner document, replace the term "complex shear modulus" with "dynamic shear modulus".
*Line 267: Which method of aging? Enter the standard.
*Figure 10 is unnecessary.
*Keep a formatting standard in the figures! Review all.
*The results are well discussed. However, the authors do not confront the findings with the existing literature. This is indispensable.
*Conclusions are long, shorten. Authors should be concise and clearly answer the objective of the paper.
*References are missing. The authors overlook several publications on the topic. These publications will help revise the results discussion section.
Author Response
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Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
1. Figure 8 shows the weight loss of PCM starting from the ambient temperature. Is this weight loss because of degradation or evaporation?
If the PCM is so volatile, how is the loss of PCM prevented when mixing with GP (shown in Figure 5) and asphalt? Is the loss of PCM account for the absence of low-temperature weight loss and thermal transition in the TGA and DSC profiles of GPCM, respectively?
If the low thermal conductivity of GP (need reference) results in no melting of GPCM, will the melting appear at a slower heating rate or prolonged heating? This thermal transition is vital to support the benefit of adding PCM into asphalt, as described in the Introduction.
2. Although interpreting the ESEM images is not the focus of this manuscript, what is the insight into the effects of PCM or GPCM?
3. In Figure 10, the baselines are not at the same level, e.g., 5%GPCM has a higher baseline than 7%GPCM. Besides, the transmittance is affected by the sample preparation, e.g., thicker samples show lower transmittance. Without subtracting the baseline and normalizing the peak height (to either internal or external reference), comparing the peak values is not accurate, as in Line 489.
4. In Figure 3, the notes in figures are not consistent with the caption.
Author Response
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Author Response File: Author Response.docx
Reviewer 2 Report
My previous comments have not been addressed.
Point-to-point reply to reviewer's comments is required, which is not provided.
Nothing is changed in the main manuscript.
Author Response
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Author Response File: Author Response.docx
Reviewer 5 Report
applsci-2191202 - R1:
The authors did not respond point by point to my comments. In addition, the markings must be clear in the text.
Follow my comments:
*The topic is current.
*Lines 1-3: The title is appropriate.
*Lines 9-15: The abstract is adequate as it contains all the elements: brief introduction; main goal; method; main findings; and conclusion.
*Lines 26-27: Do not use acronyms as keywords.
*Lines 29-35: Nanomaterials are also used.
Add:
https://doi.org/10.1016/j.ijfatigue.2022.107440
https://doi.org/10.1016/j.conbuildmat.2022.128087
*Lines 111-112: Review this sentence: “From the author’s point of view, there is no previous published data found to provide comprehensive insight on incorporating these additives in asphalt binders.” I disagree with the authors.
Clearly present at the end of the introduction the contribution of the paper to the area of knowledge.
*Lines 122-127: Justify the choice of ligands and inform the standards used in their characterization Table 1 and 2).
*Line 132: Justify the %.
*Discuss about Figure 1
*Improve the quality of Figure 1; and, present the characterization data of figure 1 in the text. Report all standards.
*Lines 144-172: Justify the percentages used;
*Lines 190-199: Justify the parameters used in the preparation (time, temperature, RPH). Justify the choice of proportions? Is it based on existing studies?
*In table 3, justify the proportion of additives.
*Lines 217-223: Inform the spindle used and the standard.
*Lines 224-237: Does this process have a standard? If not, inform studies that also performed this procedure.
*Equipment figures are unnecessary. Inform in the text the brand and model of the equipment used, as well as the city and country of manufacture.
*In the inner document, replace the term "complex shear modulus" with "dynamic shear modulus".
*Line 267: Which method of aging? Enter the standard.
*Figure 10 is unnecessary.
*Keep a formatting standard in the figures! Review all.
*The results are well discussed. However, the authors do not confront the findings with the existing literature. This is indispensable.
*Conclusions are long, shorten. Authors should be concise and clearly answer the objective of the paper.
*References are missing. The authors overlook several publications on the topic. These publications will help revise the results discussion section.
Author Response
Please see the attachment
Author Response File: Author Response.docx
Round 3
Reviewer 1 Report
1. In Figure 8, the green curve shows the weight loss of PCM starts at 25 °C, instead of at a higher temperature as the author replied to Question 1.
2. If the authors claim the weight loss of PCM is not due to degradation, please rephrase the word “degradation” in Line 343, 346, 350, 358, 362, 292, 401, etc.
3. If the weight loss of PCM is not due to degradation or evaporation, how do the authors interpret the mechanism of weight loss?
4. Line 230 has an incomplete reference.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 5 Report
A good review was carried out.
Author Response
Thank you!
