Effect of Fine Aggregate Gradation on Macro and Micro Properties of Cold Recycling Mixture Using Emulsified Asphalt
, Kexin Li 1, Jianmin Zhang 2, Ruibo Ren 1,*, Pinru Du 3, Pinhui Zhao 1, Quanman Zhao 1 and Litao Geng 1
Round 1
Reviewer 1 Report
The manuscript studied the effect of fine aggregate content on the mechanical strength, triaxial shear resistance, and fracture energy of cold recycling mixture using emulsified asphalt. This manuscript needs essential modifications as follows:
- The language of the manuscript must be improved. For example, the first sentence in the abstract is very long, i.e., it consists of four lines.
- The data of Reference 32 must be corrected and completed. All references must be checked.
- The literature study must be enriched. In this respect, authors must read and refer to the following papers:
- https://doi.org/10.1080/10298436.2018.1555332
- https://doi.org/10.1590/1679-78255516
- https://doi.org/10.1016/j.conbuildmat.2022.127075
- https://rosap.ntl.bts.gov/view/dot/36802
- https://doi.org/10.1016/j.jksues.2022.04.001
- Table 5, Last raw, what is the meaning of nFA? All mixes have the same fine aggregate content (42.6% < 4.75 mm). The difference between these mixes is the grading of the fine aggregate of the same content. Therefore, the manuscript must be rewritten based on this observation.
- Calculation procedures must be presented and explained with equations for each property. How was triaxial compressive fracture energy calculated? What is its unit? (Table 7).
Author Response
Dear reviewers:
Thank you very much for your comments.
We have checked all the comments in our paper one by one. The works has been fully revised just as following:
Point 1: The language of the manuscript must be improved. For example, the first sentence in the abstract is very long, i.e., it consists of four lines.

Response 1: The full text was read through and modified where necessary.
Point 2: The data of Reference 32 must be corrected and completed. All references must be checked.
Response 2: Reference 32 has been corrected and all references have been checked.
Point 3: Table 5, Last raw, what is the meaning of nFA? All mixes have the same fine aggregate content (42.6% < 4.75 mm). The difference between these mixes is the grading of the fine aggregate of the same content. Therefore, the manuscript must be rewritten based on this observation.
Response 3: nFA is fine aggregate grading coefficient based on N method grading theory revised by A.N. Talbol. And it has been supplemented in the article. As you mentioned，all mixes has same fine aggregate content. Fine aggregate grading may be more appropriate. Therefore, I have replaced the “fine aggregate content” with the “fine aggregate gradation”.
Point 4: The literature study must be enriched. In this respect, authors must read and refer to the following papers:
https://doi.org/10.1080/10298436.2018.1555332
https://doi.org/10.1590/1679-78255516
https://doi.org/10.1016/j.conbuildmat.2022.127075
https://rosap.ntl.bts.gov/view/dot/36802
https://doi.org/10.1016/j.jksues.2022.04.001
Response 4: Firstly, thanks for your recommendation of these articles. I have read all the articles carefully. Many findings of these articles are very enlightening to me. Four of those have been cited in my revised manuscript. And the literature study had been enriched.
Point 5: Calculation procedures must be presented and explained with equations for each property. How was triaxial compressive fracture energy calculated? What is its unit? (Table 7).
Response 5: It has been supplemented in the revised manuscript: The fracture energy is calculated according to the stress-strain curve, as shown in Figure1. It is the energy required for failure of the mixture when it begins to be compressed until it reaches the maximum stress. According to the calculation method, its unit is N/cm2.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The paper "Effect of Fine Aggregate Content on Macro and Micro Properties of Cold Recycling Mixture using Emulsified Asphalt" is well structured and written by the authors, and I believe it has publication potential, however some minor corrections are needed:
(1) The abstract must be improved, authors must add quantitative information of their main results;
(2) The state of the art and literature on the subject is still limited. Authors should be able to effectively showcase the innovation and contribution of this research. I suggest adding some searches like: 10.1016/j.conbuildmat.2022.126357; 10.1617/s11527-021-01877-6; 10.1016/j.cscm.2021.e00596.
(3) There are several results that are presented in the methodology section, this is not correct and a section of these characterizations should be created in the results section;
(4) "Thus, the adhesion between aggregate, emulsified asphalt mortar and cement hydration products was increased. Macroscopic strength of CRME was enhanced." Authors should improve this discussion and explanation of this item with other studies in the literature;
(5) The conclusion should show some advances and gaps in the literature;
Author Response
Dear reviewers:
Thank you very much for your comments. And thank you very much for your recognition of our works.
We have checked the comments in our paper. Some work has been revised as following:
Point 1: The abstract must be improved; authors must add quantitative information of their main results.
Response 1: Abstract has been supplemented in the revised manuscript.
Point 2: The state of the art and literature on the subject is still limited. Authors should be able to effectively showcase the innovation and contribution of this research. I suggest adding some searches like:
https://doi.org/10.1016/j.conbuildmat.2022.126357;
https://doi.org/10.1617/s11527-021-01877-6;
https://doi.org/10.1016/j.cscm.2021.e00596.
Response 2: The art and literature study has been enriched. Thank you for recommending articles. All the articles have been read and many findings are very enlightening to me. Those has been cited in my revised manuscript.
Point 3: There are several results that are presented in the methodology section, this is not correct and a section of these characterizations should be created in the results section;
Response 3: Several results are the basic technical performance test results of materials, so they are presented in materials and methodology section.
Point 4: "Thus, the adhesion between aggregate, emulsified asphalt mortar and cement hydration products was increased. Macroscopic strength of CRME was enhanced." Authors should improve this discussion and explanation of this item with other studies in the literature;
Response 4: This part has been modified as required. Previous studies have also pointed out that the main effect of cement on the performance of CRME is controlled by the proportion of hydration products and entrapment state between asphalt and hydration products. Meanwhile, the proportion of ordinary filler in fine aggregate will affect the degree of cement hydration. And then affect the quantity of hydration products and the interweaving state of hydration products and asphalt
Point 5: The conclusion should show some advances and gaps in the literature;
Response 5: Advances and gaps has been replenished in revied manuscript.
Author Response File: Author Response.docx
Reviewer 3 Report
Before making any recommendations for a very interesting scientific article, I would like to present the following statements on the topic. Based on my long-term research and transfer profile in the field of holistic perception of the issues of municipal and pavement engineering, I consider the evaluated scientific article to be extremely topical and fully convergent with the following author's research and educational premise. Pavements should be designed, built, managed, maintained, recycled (decomposed) at a reasonable price, in reasonable quality, respecting the relevant requirements of users, residents and sustainable development (including minimizing the negative impacts of climate changes on settlements and regions). One such minimization measures in the field of roads may be the use of unbound permeable aggregate base (UPAB) materials with strong load-transmitting skeleton suggested in the sponge-city initiative. In an very good inspirational contribution, new scientific findings enabling the better application of CRME presented to me. Personally, I consider the article under review to be a valuable contribution to Sustainable Pavements. Kibert (1994) laid down the foundation for Sustainable construction (SC) practice, and established SC around resource minimization and reuse, use of renewable and recyclable resources, and minimizing carbon footprint. Vanegas and Pearce (2000) presented SC based on resource depletion and degradation, impact on built environment and human health, and Pulaski (2004) presented a comprehensive approach towards sustainability in construction operation, MALLICK and EL-KORCHI (2018). Sustainable construction tools and standards were first developed for buildings. The first set of assessment/rating concepts and tools in the US were provided by the: Green Building System (GBS (USGBC LEED); the origin of these tools can be traced back to UK´s Building Research establishment (BRE) environmental assessment method (BREEAM) (BRE 2006; BREEAM 2006). Subsequently other “systems“ were developed: Canada: Green Globe, Japan: CASBEE (Comprehensive Assessment System for Built Environment Efficiency), Singapore: BCA (The Building and Construction Authority) Greenmark, China: Green Olympics Building assessment System (GOBAS), Australia: Building greenhouse rating (ABGR), India: TERI-GRIHA (Green Rating for Integrated Habitat Assessment). Presented, in the conditions of Europe environmentally progressive technology of municipal waste recovery is in full compliance with Although differing in scope, the currently agreed common goals of SC are as follows: reduce carbon footprint, ecology and environmental protection, healthy indoor and outdoor environment, resource efficiency, conserve resources (land and raw materials).
Mandatory requirements:
LNSA 110...In Table 4. Test results of technical performance of emulsified asphalt... needs to be corrected 5 day /%.
LNSA 125…In Table 6. Mix design results of CRME... It is necessary to change the format of the table so that the MPa is not divided.
LNSA 143…Testing was carried out by UTM-100 with a loading rate 143 of 1 mm/min...It is necessary to explain the abbreviation of the parameter UTM-100, resp. to refer to the methodology of its determination.
LNSA 154 and 164… LNSA 116-117… 2.3.4. SEM... 2.3.5. X-ray CT... necessary to change the titles of these subchapters, it is not appropriate to give only abbreviations.
CRME was designed by modified Marshall method according to JTG/T 5521… It is necessary to add a reference to the method.
LNSA 214…In Table 6. Mix design results of CRME... It is necessary to change the format of the table so that the (N/cm2) is not divided.
LNSA 298-299…Where, r is equivalent average diameter, mm; V is volume of each air void in mixture, 298 mm3 ... It is necessary to add more detailed information to the equivalent average diameter.
LNSA 305…In Table 9. Air void equivalent average diameter of CRME with different gradations, it is necessary to add a physical unit for the Equivalent average diameter.
LNSA 306-329… The conclusions need to be reworked, the abstracted knowledge must also be quantified numerically. There are also presented duplicates: LNSA 308-309 With fine aggregate content increase, emulsified asphalt content increased obviously .... LNSA 325-326 (5) Increase of fine aggregate content resulted in increase of emulsified asphalt content in CRME. Thus, energy consumption in the triaxial test increased and flexibility enhanced, which showed that fracture energy and failure strain of triaxial test increased (LNSA 308-309). This sentence has a markedly declarative, generally stated character, which is not sufficient for the purposes of a renowned scientific journal and therefore "enlarged, enhanced, increased" must be characterized in numerical form.
Facultative recommendations:
LNSA (Line number of the scientific article) 10-22... For Abstract, I would like to present similar recommendations as I stated for the Conclusions, although in this part of the scientific contribution their incorporation is not so necessary, but it can be beneficial for readers. It would certainly be worth considering incorporating numerical or ratio quantifications of interesting findings of the authors presented especially in the following sentence. With the increase of fine aggregate content, amounts of large-volume air voids in CRME decreased and amounts of small-volume air voids significantly increased, while the equivalent diameter of air voids decreased slightly with the increase of fine aggregate content.
LNSA 28-29…Cold recycling technology, hot recycling technology, rubber asphalt technology 28 and warm mix recycling technology of asphalt pavement is widely applied [1–5]...These are probably citations of works from one country or. one continent, so it would be useful to add references to relevant works by authors from other continents.
LNSA 109.. In Table 3. Test results of technical performance of matrix asphalt... 10 °C ductility/cm, Density/(g/cm3)... It is necessary to unify the format of writing of physical units, this requirement also applies to other parts of the article under consideration.
LNSA 165...Figure 1. Nano Measurer statistical analysis... recommended to specife of the paper title to make it clear what the construction material is.
LNSA 244...In Figure 5. Interaction between hydration products and asphalt mortar of G1 mixture...It would be useful to explain the abbreviation C-S-H.
LNSA 272... Figure 7. Quantitative analysis of cement hydration products distribution... Is the label "miture" correct?
The authors presented the results of interest research into the effect of fine aggregate content on macro and micro properties of final product CRME technology saving non-renewable resources and reducing energy for pavement construction and rehabilitation. In my opinion, the presented results contribute to the scientific credibility of the mentioned environmental technology in the field of pavement engineering. The assessed article "Effect of Fine Aggregate Content on Macro and Micro Properties of Cold Recycling Mixture using Emulsified Asphalt" can be assessed as very good, containing certain shortcomings that need to be eliminated. From the aspect of high quality of the assessed contribution, in case of incorporation of comments, or relevant justification of their non-incorporation, I am able to process a repeated review within 3 days.
Author Response
Dear reviewers:
Thank you very much for your comments. And thank you very much for your recognition of our works.
We have checked the comments in our paper. Some work has been revised as following:
Mandatory requirements:
Point 1: LNSA 110...In Table 4. Test results of technical performance of emulsified asphalt... needs to be corrected 5 day /%.
Response 1: The mistake has been corrected in Table 4.
Point 2: LNSA 125…In Table 6. Mix design results of CRME... It is necessary to change the format of the table so that the MPa is not divided.
Response 2: Format of the table 6 has been changed.
Point 3: LNSA 143…Testing was carried out by UTM-100 with a loading rate 143 of 1 mm/min... It is necessary to explain the abbreviation of the parameter UTM-100, resp. to refer to the methodology of its determination.
Response 3: The loading rate of UCS was following with “Standard Test Methods of Bitumen and Bituminous Mixtures for Highway Engineering” (JTG E20-2011), which has been cited in revised manuscript.
Point 4: LNSA 154 and 164… LNSA 116-117… 2.3.4. SEM... 2.3.5. X-ray CT... necessary to change the titles of these subchapters, it is not appropriate to give only abbreviations. CRME was designed by modified Marshall method according to JTG/T 5521… It is necessary to add a reference to the method.
Response 4: All of these have been revised in revised manuscript.
Point 5: LNSA 214…In Table 6. Mix design results of CRME... It is necessary to change the format of the table so that the (N/cm2) is not divided.
Response 5: Format of the table 7 has been changed.
Point 6:LNSA 298-299…Where, r is equivalent average diameter, mm; V is volume of each air void in mixture, 298 mm3 ... It is necessary to add more detailed information to the equivalent average diameter.
Response 6: firstly, I’m so sorry for making a mistake here: r is equivalent average radius, and it has been corrected. And detail information has been provided as following.
Air voids was equivalent to a sphere of same volume, and the radius of the sphere corresponding to the same volume as the air void was defined as the equivalent radius of the air voids. All equivalent radius of each air void in the mixture were averaged, and this was called the equivalent average radius. Equivalent average radius was used to describe the distribution characteristics of air void size. The calculation method of equivalent average radius is shown in Equation 1.
|
|
(1) |
Where, r is equivalent average radius, mm; Vi is volume of air void numbered i, mm3; n is total amounts of air voids in mixture.
Point 7: LNSA 305…In Table 9. Air void equivalent average diameter of CRME with different gradations, it is necessary to add a physical unit for the Equivalent average diameter.
Response 7: I'm very sorry for missing the unit of equivalent average radius (mm), which has been added in Table 9.
Point 8: LNSA 306-329… The conclusions need to be reworked; the abstracted knowledge must also be quantified numerically. There are also presented duplicates: LNSA 308-309 With fine aggregate content increase, emulsified asphalt content increased obviously .... LNSA 325-326 (5) Increase of fine aggregate content resulted in increase of emulsified asphalt content in CRME. Thus, energy consumption in the triaxial test increased and flexibility enhanced, which showed that fracture energy and failure strain of triaxial test increased (LNSA 308-309). This sentence has a markedly declarative, generally stated character, which is not sufficient for the purposes of a renowned scientific journal and therefore "enlarged, enhanced, increased" must be characterized in numerical form.
Response 8: Both conclusion and abstract part were revised following your suggestion.
Facultative recommendations:
Point 1: LNSA (Line number of the scientific article) 10-22... For Abstract, I would like to present similar recommendations as I stated for the Conclusions, although in this part of the scientific contribution their incorporation is not so necessary, but it can be beneficial for readers. It would certainly be worth considering incorporating numerical or ratio quantifications of interesting findings of the authors presented especially in the following sentence. With the increase of fine aggregate content, amounts of large-volume air voids in CRME decreased and amounts of small-volume air voids significantly increased, while the equivalent diameter of air voids decreased slightly with the increase of fine aggregate content.
Response 1: Abstract part has been revised following your suggestion.
Point 2: LNSA 28-29…Cold recycling technology, hot recycling technology, rubber asphalt technology 28 and warm mix recycling technology of asphalt pavement is widely applied [1–5]...These are probably citations of works from one country or. one continent, so it would be useful to add references to relevant works by authors from other continents.
Response 2: This part has been rewrite.
Point 3: LNSA 109.. In Table 3. Test results of technical performance of matrix asphalt... 10 °C ductility/cm, Density/(g/cm3)... It is necessary to unify the format of writing of physical units, this requirement also applies to other parts of the article under consideration.
Response 3: It has been checked and unified.
Point 4: LNSA 165...Figure 1. Nano Measurer statistical analysis... recommended to specife of the paper title to make it clear what the construction material is.
Response 4: It has been supplemented: Figure 2. Nano Measurer statistical analysis for CRME (G1 mixture).
Point 5: LNSA 244...In Figure 5. Interaction between hydration products and asphalt mortar of G1 mixture...It would be useful to explain the abbreviation C-S-H.
Response 5: Abbreviation C-S-H has been explained: calcium silicate hydrate (C-S-H) is mostly amorphous.
Point 6: LNSA 272... Figure 7. Quantitative analysis of cement hydration products distribution... Is the label "miture" correct?
Response 6: The spelling of "miture" has been replaced by "mixture" in Figure 8.
Author Response File: Author Response.docx
Reviewer 4 Report
Effect of Fine Aggregate Content on Macro and Micro Properties of Cold Recycling Mixture using Emulsified Asphalt
The paper presents research to explore the influence of fine aggregate on the macro and micro properties of cold recycling mixture using emulsified asphalt (CRME).
Comments
Strengths of the paper:
- Professionally laid out paper – both academic and practical, comprehensive, clear, and solid in terms of descriptive content and proposed considerations/applications.
- Review references (34) on the considered topic and a review of published research works presented.
- Well thought out the methodology by using different approaches and methods.
- The proposed methods seem to be innovative and contain well-known hints of originality.
- The results of the tests showed that with the increase of fine aggregate content, amounts of large-volume air voids in CRME decreased and amounts of small-volume air voids significantly increased, while the equivalent diameter of air voids decreased slightly with the increase of fine aggregate content.
Weakness of the paper:
- I advise increasing the review references, in particular regarding the evaluation of air voids using X-ray computed tomography.
- The authors should try to generalize the results by highlighting how the results can improve pavement performance.
- Authors should anticipate some results in the abstract to capture the readers’ curiosity.
- Abbreviations should be defined when first used.
- The abbreviation AFt should always be written the same way in the paper (many times it is written Aft).
- It would not be superfluous to briefly introduce the cement hydration process and the importance of product AFt.
- In addition to the data reported in Table 8, in my opinion, a graphical representation with the cumulative distributions of air void amount in the mixtures would be more effective (see the enclosed graph)
- In the Conclusions, it would be appropriate to briefly resume the description of the experimental analyses carried out and an explanation of the importance of the study in the light of the results achieved.
- … no more weaknesses!
The overall merit of the presented research work is adequate and worth publishing after incorporating the above suggestions.
Comments for author File: 
Comments.pdf
Author Response
Dear reviewers:
Thank you very much for your comments. And thank you very much for your recognition of our works.
We have checked the comments in our paper. Some work has been revised as following:
Point 1: I advise increasing the review references, in particular regarding the evaluation of air voids using X-ray computed tomography.
Response 1: Literature study had been enriched. Research about evaluation of air voids using X-ray CT has been replenished.
Point 2: The authors should try to generalize the results by highlighting how the results can improve pavement performance.
Response 2: Several suggestions have been provided in this paper. Both the quantity, size, formation of interleaving structure of cement hydration products, and the number, distribution, size of air voids were the key to determine the performance of CRME. Therefore, in order to improve the performance of CRME, it is necessary to ensure the hydration quality of cement; increase the proportion of ordinary filler, improve compaction effect to reduce the amounts of large volume air voids as much as possible.
Actually, authors plan attempts to optimize the gradation composition of CRME, and analyse the relationship between hydration quality, number of voids, mechanical properties and ordinary filler content. Then give the range of ordinary filler for improve CRME performance.
Point 3: Authors should anticipate some results in the abstract to capture the readers’ curiosity.
Response 3: Abstract has been rewritten, and quantitative information of main results has been supplemented.
Point 4: Abbreviations should be defined when first used.
Response 4: Full text has been checked and revised.
Point 5: The abbreviation AFt should always be written the same way in the paper (many times it is written Aft).
Response 5: Full text has been checked and all the Aft has been revised.
Point 6: It would not be superfluous to briefly introduce the cement hydration process and the importance of product AFt.
Response 6: The hydration process was briefly described, and the importance of hydration products to macroscopic strength was described. The reason of chosen AFt for quantitatively analysis were clarified.
Point 7: In addition to the data reported in Table 8, in my opinion, a graphical representation with the cumulative distributions of air void amount in the mixtures would be more effective (see the enclosed graph)
Response 7: Thank you for your suggestions and examples. Table 8 has been replaced by Figure 9 (cumulative distributions of air void amount)，see attachment file.
Point 8: In the Conclusions, it would be appropriate to briefly resume the description of the experimental analyses carried out and an explanation of the importance of the study in the light of the results achieved.
Response 8: Conclusion part has been supplemented: The influence of fine aggregate gradation on mechanical property, hydration products and air void structure were studied by macro and micro test. Ultimate cause on influence of fine aggregate gradation on the strength of CRME was revealed. However, the research will deeply explore the influence of air void morphology, to find relationship between air void morphology parameters and mixture strength.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The authors have successfully addressed all my comments. Therefore, I recommend the publication of this manuscript.
Reviewer 3 Report
At the end of the first review, I anticipated the high quality of the 2nd version of the article under review in the following form.
The authors presented the results of interest research into the effect of fine aggregate content on macro and micro properties of final product CRME technology saving non-renewable resources and reducing energy for pavement construction and rehabilitation. In my opinion, the presented results contribute to the scientific credibility of the mentioned environmental technology in the field of pavement engineering. The evaluated article "Effect of Fine Aggregate Content on Macro and Micro Properties of Cold Recycling Mixture using Emulsified Asphalt" can be assessed as very good, containing certain shortcomings that need to be eliminated. From the aspect of high quality of the assessed contribution, in case of incorporation of comments, or relevant justification of their non-incorporation, I am able to process a repeated review within 3 days.
I am pleased to say that the authors have credibly fulfilled my prediction of the final quality of the article and the authors have incorporated virtually all the recommendations, including optional ones. Based on the quality of the submitted version of the scientific paper: "Effect of Fine Aggregate Gradation on Macro and Micro Properties of Cold Recycling Mixture using Emulsified Asphalt", I am pleased to say its excellent quality. At the same time, I would like to express my sincere thanks to the publishers as well as the authors for the opportunity to broaden my scientific horizon.
Based on the above facts, I decided to manage the report not within 3 days but within 1 day, which is actually within 3 days.
I have the only formal request for the submitted version, namely to add a dot at the end of the reference 31. JTG E20-2011; Standard Test Methods of Bitumen and Bituminous Mixtures for Highway Engineering. Ministry of Transport of the People’s Republic of China: Beijing, China, 2011
Sincerely and congratulations again on an excellent article
Review author
