Mechanism of HCB-Modified Asphalt and Dynamic Properties of Mixtures
Round 1
Reviewer 1 Report
The authors investigated the physical and rheological properties of Hydroxymethyl carbon black modified asphalts and carbon black modified asphalts.
The paper is well written and organized and connections are covered in the paper. Please see the minor comment below:
Line 130: Please rewrite the sentence “the its…”
Line 130: “floc is significantly reduced.” Is this concluded from Fig. 3?
Besides this, I've found the paper fit for publication.
Author Response
Point 1: Line 130: Please rewrite the sentence “the its…”
Response 1: Thanks for the respectful reviewer’s valuable comments. The sentence “the its…” rewrite has been rewritten.
Point 2: Line 130: “floc is significantly reduced.” Is this concluded from Fig. 3?
Response 2: Yes. From Fig.3, the surface of HCB is smoother than that of CB and the floc is apparently reduced.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Interesting findings are reported and the reviewer would like to thank authors for their efforts. Authors are encouraged the issues listed below.
- English language of the presentation needs improvement. Occasional grammatical errors are observed in the manuscript. Also, in several cases manuscript lacks flow. It is important to have the manuscript edited properly.
- Asphalt mix volumetric properties need to be clearly presented. For example, Pbe, Gse, VMA, VFA, DR, etc.
- While HCB and CB have been tested using SEM, EDS, and FTIR methods the implications of the outcomes of these tests have not been properly discussed in the context of the tests conducted on asphalt mixes., For example, it is not clear how the chemical compositions of the HCB or CB have affected the asphalt binder's chemical structure that has caused it to soften. Discussion is suggested to be added.
- This is a study with a limited scope. Therefore, generalization of the results should be avoided in conclusion section. Also, a short discussion highlighting the study limitations is suggested to be added.
Author Response
Point 1: English language of the presentation needs improvement. Occasional grammatical errors are observed in the manuscript. Also, in several cases manuscript lacks flow. It is important to have the manuscript edited properly.
Response 1: Thanks for the respectful reviewer’s valuable comments. We have checked and revised our manuscript carefully for grammar errors. And we have asked Javed Akhtar to help us with the revision again. He is an international doctoral student in our research team from Pakistan.
Point 2: Asphalt mix volumetric properties need to be clearly presented. For example, Pbe, Gse, VMA, VFA, DR, etc.
Response 2: Thanks for the respectful reviewer’s valuable comments. The volumetric properties of base asphalt mixture (BAM) and hydroxymethyl carbon black modified asphalt mixture (HAM) have been clearly presented in Table 3.
Table 3 Parameters of asphalt mixture for Marshall design method
|
Asphalt mixture |
OAC, % |
VV, % |
VMA, % |
VFA, % |
MS, kN |
Flow value, mm |
||
|
|
BAM |
4.5 |
3.95 |
14.5 |
72.8 |
12.5 |
3.1 |
|
|
|
HAM |
4.5 |
4.18 |
14.4 |
72.3 |
13.4 |
2.5 |
|
Related content has been added to the manuscript.
Point 3: While HCB and CB have been tested using SEM, EDS, and FTIR methods the implications of the outcomes of these tests have not been properly discussed in the context of the tests conducted on asphalt mixes., For example, it is not clear how the chemical compositions of the HCB or CB have affected the asphalt binder's chemical structure that has caused it to soften. Discussion is suggested to be added.
Response 3:
Thanks for the respectful reviewer’s valuable comments.
Oxygen-containing functional groups such as -OH are formed on the surface of HCB, increasing the polarity of carbon black surface. As a result, the adsorption among HCB particles is weakened, and the dispersion capability in asphalt is improved. The interaction effect between HCB and asphalt and the particle effect are enhanced, which increases the viscosity and strengthens the resistance to shear-slip deformation of HCB modified asphalt.
There are a certain number of hydrogen bonds in HCB modified asphalt. The hydrogen bond will break after absorbing enough energy and TFOT can provide enough thermal energy for the hydrogen bonds, preventing the aging of BA. Polycondensation and oxidation reactions happed in the asphalt during aging process, increasing the number of carbonyl functional groups. These reactions increase the number of hydrogen bonds in the HCB modified asphalt, which has a positive effect on improving the aging resistance of the asphalt.
Related content has been added to the manuscript.
Point 4: This is a study with a limited scope. Therefore, generalization of the results should be avoided in conclusion section. Also, a short discussion highlighting the study limitations is suggested to be added.
Response 4:
Thanks for the respectful reviewer’s valuable comments.
The conclusion has been revised.
This paper only investigated the physical and rheological properties of HCB modified asphalt and dynamic properties of its mixture and does not compare with other modified asphalt. In the following research, the rubber and SBS modified asphalt will be studies, and then the modified effects of these modified asphalts will be compared.
Related content has been added to the manuscript.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The reviewer appreciates authors effort put in improving the manuscript according to review comments.
