The Development of a New Thermoplastic Elastomer (TPE)-Modified Asphalt
Round 1
Reviewer 1 Report
The study carried out is good, based on experiments in the laboratory and supported by conclusions. The introduction is extensive and highlights the problem of protecting the environment, respectively the need to use plastic and rubber powder in the production of asphalt.
Regarding the topic, there are not a large number of articles in this regard, but the advantages of using rubber powder in the composition of asphalt are very well known.
Regarding the template, the article must be rearranged and include a grammatical correction.
Author Response
The study carried out is good, based on experiments in the laboratory and supported by conclusions. The introduction is extensive and highlights the problem of protecting the environment, respectively the need to use plastic and rubber powder in the production of asphalt.
Regarding the topic, there are not a large number of articles in this regard, but the advantages of using rubber powder in the composition of asphalt are very well known.
Regarding the template, the article must be rearranged and include a grammatical correction.
Response:
Thank your comments. Based on the formatting requirements of the article, this article has made modifications to the entire text. Especially the images have been completely redrawn.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The paper deals with the development and assessment of a new TPE modifier to be employed in the bitumen modification. The performance of the TPE modified asphalt were analyzed by means of empirical testing (penetration, softening point, ductility, and viscosity indexes). Fluorescence microanalysis was also performed to analyze the microscopic mechanism of the TPE modified asphalt.
The investigated topic is interesting specifically in this time where the use of secondary materials is encouraging. The explanations of the adopted procedures and obtained results presented too much confusion in the description (especially in the section 2 and 3) which does not allow to fully understand what has been done and achieved.
A limitation of the study is the use of traditional test instead a more appropriate rheological approach, which is essential to highlight the different behavior of non traditional binders, especially those produced using recycling materials (which may influence the overall stability of the binder and its durability). The influence, for example, of the aging shall be carried out to fully understand the interaction between the bitumen matrix and the additives adopted.
Moreover, what about the stability od the new modified bitumen? Storage stability test is fundamental for these types od new binders in which sedimentation and phase separation represents a critical point and may strongly influence the final properties of the bitumen.
The Authors should add more References to the different statements they introduced in the “Introduction” section, highlighting also the results obtained by the different research (in some cases just a mention of the type of materials investigated is presented).
In some parts of the text an extensive language review could be necessary to avoid any difficulty in reading and understanding the text (repetitions and too long sentences, sometimes missing subjects and punctuation, grammar and syntax mistakes), leading to some confusion in the reading (especially for the discursive parts, e.g. page 2, lines 42-44).
Pay attention to the formatting of the text and Table, there seem to be several differences throughout the text.
Comments for author File: Comments.pdf
Author Response
The paper deals with the development and assessment of a new TPE modifier to be employed in the bitumen modification. The performance of the TPE modified asphalt were analyzed by means of empirical testing (penetration, softening point, ductility, and viscosity indexes). Fluorescence microanalysis was also performed to analyze the microscopic mechanism of the TPE modified asphalt.
The investigated topic is interesting specifically in this time where the use of secondary materials is encouraging. The explanations of the adopted procedures and obtained results presented too much confusion in the description (especially in the section 2 and 3) which does not allow to fully understand what has been done and achieved.
Response:
Thank your comments. I deeply apologize for any inconvenience caused to your understanding. Due to the fact that the TPE material studied in this article needs to be developed through multiple formulations and involves multiple modifiers, there is a certain degree of understanding error due to the use of numbering for reference. Further optimization is needed in the future to ensure smooth understanding.
A limitation of the study is the use of traditional test instead a more appropriate rheological approach, which is essential to highlight the different behavior of non traditional binders, especially those produced using recycling materials (which may influence the overall stability of the binder and its durability). The influence, for example, of the aging shall be carried out to fully understand the interaction between the bitumen matrix and the additives adopted.
Response:
Thank your comments. This article mainly studies TPE using three major indicators, viscosity, fluorescence microscopy, and other methods. Further research on the rheological properties of TPE through means such as DSR is needed to ensure that TPE materials can be applied in the engineering field.
Moreover, what about the stability od the new modified bitumen? Storage stability test is fundamental for these types od new binders in which sedimentation and phase separation represents a critical point and may strongly influence the final properties of the bitumen.
Response:
Thank your comments. The storage stability of modified asphalt is mainly characterized through segregation tests and evaluated by the difference in softening point â–³ts between the top and bottom. According to the technical standards for modified asphalt in China, when Δts ≤ 2.5 ℃, the stability of modified asphalt is qualified. On this basis, the morphology of modified asphalt at high temperatures was also analyzed using optical microscopy and transmission electron microscopy. From Table 8 in the paper, it can be seen that the composite activation system is superior to a single system, especially in terms of the stability performance of modified asphalt.
1) Similar to the modified asphalt with a single activator system, the modified asphalt with L-B added in the composite system has the best stability.
2) The addition of plant-based softener S-1 can improve the softening point of modified asphalt.
3) In the composite system, the changes in the content of L-A and S have little effect on the performance of modified asphalt, and the performance indicators do not change with the changes in their content.
4) Compared with other composite systems, the softening point of the modified asphalt system added with L-B is slightly lower.
The Authors should add more References to the different statements they introduced in the “Introduction” section, highlighting also the results obtained by the different research (in some cases just a mention of the type of materials investigated is presented).
Response:
Thank your comments. Some literature has been added in the introduction to provide a richer explanation of the research content.
In some parts of the text an extensive language review could be necessary to avoid any difficulty in reading and understanding the text (repetitions and too long sentences, sometimes missing subjects and punctuation, grammar and syntax mistakes), leading to some confusion in the reading (especially for the discursive parts, e.g. page 2, lines 42-44).
Response:
Thank your comments. By organizing the entire text, the grammar has been modified.
Pay attention to the formatting of the text and Table, there seem to be several differences throughout the text.
Response:
Thank your comments. The table format of the entire text has been modified to make it uniform.
The Authors introduce TPE modified asphalt highlighting the environmental value but without underlining which are the components. I would describe the TPE composition before celebrating the benefits.
Response:
Thank your comments. Polymerized "alloy" materials, using (recycled) plastics and (waste) vulcanized rubber powder as the main polymer raw materials, are fully combined with asphalt components in the thermodynamic process under the action of some selected composite organic additives. Physical and chemical reactions between different components are completed in dynamic mixing. Different types of reactions should occur simultaneously in the mixing without mutual inhibition, It can establish synergistic effects between various components or heterogeneous phases, dissolve each other, and establish a morphological structure similar to thermoplastic elastomers TPE and TPR. This thermoplastic highly asphalt alloy material can be extruded, granulated, cooled and solidified, stored at room temperature without adhesion, and is convenient for industrial packaging and transportation.
The Authors introduced several results from literature relating to the use of rubber and waste plastics but without providing any references. Since this is the “Introduction”, readers expect to have adequate references.
Response:
Thank your comments. In the introduction section, some literature has been added to facilitate readers to have a clearer understanding of the current development status in this field.
The Authors mentioned that “rheological properties” were analyzed, but at the end of reading I can’t see information about the rheological behavior of the TPE asphalt investigated. What were they referring to?
Response:
Thank your comments. The rheological properties mentioned in this article are mainly analyzed from traditional indicators such as softening point, penetration, and ductility, and are not applied to instruments and indicators specifically used to study the rheological properties of materials such as DSR.
In the “Penetration” double (0.1 mm) is reported. Moreover, some units are missing (e.g. “Softening point”). Is the difference between the ductility specs at 10 °C and 15 °C so big?
Response:
Thank your comments. The (0.1 mm) has been deleted.
According to the technical standards for road asphalt petroleum, the technical indicators for ductility at 10 ℃ and 15 ℃ are shown in Table 1. The gap between the two is indeed very large.
Pay attention to the formatting, different from Table 1
Response:
Thank your comments. All table formats have been modified.
I don’t see in the raw materials the waste plastic. Probably it is my fault but wasn't the TPE made using both waste rubber powder and waste plastic? If yes, additional Table “Physical properties of waste plastic” should be added.
Response:
Thank your comments. The indicators for waste plastics have been added, as shown in Table 1.
Table 1. Physical properties of waste plastic
|
Technical indicators |
Measured results |
|
Density/（g/cm3） |
0.915 |
|
Melt index/g/10min |
4.12 |
|
Melting peak temperature/% |
1.48 |
|
MD yield tensile strength/MPa |
9.5 |
|
MD breaking tensile strength/MPa |
48 |
|
Gloss/45℃ |
44 |
|
Haze/% |
4.5 |
“TPR” stand for?
Response:
Thank your comments. TPR has been deleted.
“S” stand for “S-1”, the vegetable oil-based activator?
Response:
Thank your comments. S1-S7 represents the formula and process for preparing activated waste rubber powder by adding different activators.
All the Figures should be improved.
Response:
Thank your comments. The Figures have been completely redrawn.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The authors have improved the paper and largely satisfied the Reviewer's requests, so the paper can be considered ready for publication.
