Research on the Calibration Method of the Bonding Parameters of the EDEM Simulation Model for Asphalt Mixtures
Angelo Filonzi
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsTitle
Predictive Modeling of Splitting Tensile Strength of Asphalt Mixtures Based on EDEM
Abstract
Line 13 – The words “in this paper” are repeated. Please remove them in both sentences.
Line 14 – Remove the word “selected”.
I’m not clear if the abbreviation DEM or EDEM means “discrete element simulation” or “discrete element simulation”. Please double check the abstract and keywords. It confuses the reader. Please make it consistent in the entire manuscript.
According, with the introduction several researchers have been using discrete element simulation using different methods. Can you please include and specify in the abstract what is new in your current research/manuscript?
Introduction
Line 39 – Are all these 3-9 citations needed? Split these citations and refer them when it is required only.
Line 39 – Define: PFC2D, PFC3D, and EDEM.
Line 45 – Define CAE.
Line 50 – Why discrete element method is shown with capital letter? Please, be consistent in the entire manuscript. Sometimes it shows without capital letter and sometimes with capital letter.
Line 76 – Change “this paper” to “this study”.
Materials and Methods
Also, why you didn’t select a neat/unmodified binder for comparison purposes? This study, uses a modified asphalt binder only. Is there a reason to not use an unmodified binder in the software? Can the software/model detect the different behaviors between modified and unmodified binders? Please, add some comments and information in the manuscript.
Line 84 – Define SBS.
Line 85 - Avoid the use of “In this paper…” in the entire manuscript.
Table 1 to 4 – Please, improve the title of these tables. These tables show required values from the specifications and also the test results values. E.g. Table 1 - “Technical indicators by specifications and test results for …….. ”. Please, improve them accordingly.
Line 98 – Do not use the phrase: “In this paper”. Please, remove it.
Table 5 – Is it possible to show the gradation in a graph instead of a table? Plots help to understand if the aggregate gradation is fine or coarse, etc. Please use the term “aggregate gradation” to refer to the gradation in the entire manuscript.
Line 103 – Avoid the use of “In this paper…” in the entire manuscript.
Line 103 – Why did you decide to name the indirect tensile test (IDT) as splitting tensile strength test?
Line 109 – In the Equation 1……
Table 6 – What are the typical dimensions of Marshall samples? Please, include this information in table 6. Height, diameter? This will help to have an idea with IDT tests from SGC.
EDEM Simulation Modeling of Asphalt Mixtures
Line 124 and 125 – Please revise this sentence. Should the normal and shear stresses exceed their critical values, the ‘Bond’ will fracture and will not regenerate.
Figure 1 – Revise the title: “Interaction of the 'Bond' between Particle A and Particle B”.
Line 150 – For better clarification, refer asphalt as an “asphalt binder” in the entire manuscript.
Line 175 – Remove “in this paper” in the entire manuscript.
Table 8 – Double check the title. Why use capital letter? Be consistent in the entire manuscript.
For particle generation and compaction process: What are the main differences between a Marshall compactor versus a Superpave Gyratory Compactor model? Can this model/software be used to model a gyratory compactor? How do you avoid the segregation of the particles? Are the small particles grouped at the bottom and coarse particles at the top? How do you avoid this situation? How do you achieve a good distribution of the particles?
Figure 4 – It looks like the sample after compaction has a high amount of asphalt mortar particles. Is it true? Table 10 shows that 36.1% represents asphalt mortar, but the cross-section in Figure 5 visually looks different. Can you please clarify and explain in the manuscript?
Figure 6 – Improve the scale of the figures.
Predictive Modeling of Splitting Tensile Strength of Asphalt Mixtures
Can you please briefly explain what is a “response surface experiment”? and how it was conducted?
Line 250 – remaining terms ARE not significant. Please, correct.
Figure 7 – Please, double check the scale of these figures.
Verification of EDEM simulation model for asphalt mixtures
Line 287 – Remove “in this paper” in the entire manuscript.
Conclusions
This study states that “the EDEM simulation of asphalt mixture yields a splitting tensile strength with a mere -2.48% relative error compared to laboratory tests”. This must be carefully evaluated due to the lack of different gradations, aggregate type, and asphalt binder type used.
The manuscript summarizes only two points in their conclusions.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsCoatings-3331852:
Follow my comments:
*The description of the calibration process for bonding parameters in the Hertz-Mindlin with bonding contact model could be more detailed, explaining the exact criteria used for selecting initial values and adjusting the parameters.
*The discussion section lacks a deeper analysis of the simulated results compared to experimentol data available in the literature.
*The authors could expand the contextualization of the results to indicate how this model improves upon or difers from previous approaches in EDEM simulation.
*The conclusion section does not adequately address the limitations of the study, such as the simplification of the asphalt mortar model using spherical particles.
*The practical impact of the research for the pavement industry, such as cost optimizations or performance improvements, is not sufficiently explored.
*Although the article mentions the use of response surface methodology, there is little explanation about the statistical validity of the adjusted model, such as residual analysis or significance tests.
*The comparison of results with similar studies is limited. Citing more works utilizing DEM simulations for asphalt mixtures would be beneficial.
*Figures, such as the response surface diagram (Figure 7), could be accompanied by more detailed textual explanations, better connecting the graphs to the findings.
*The nomenclature used to describe the model parameters (e.g., 𝑋₁, 𝑋₂, etc.) should be better explained upon first mention to avoid confusion throughout the text.
*Some reference cited are old theses and dissertations, which may not reflect the current state of the art. Updating these references with recent articles would strengthen the paper.
*The process for preparing the asphalt mixture samples for laboratory testing is described very briefly and could be expanded.
*Some sentences in the article are redundant, such as "In this paper, three representative coarse aggregate particles selected were modeled in 3D using SolidWorks software and imported into EDEM software." Repetitions could be eliminated for better clarity.
*Subjective terms such as "obvious advantages" and "typical discontinuous numerical simulation" should be avoided or explained with greater scientific rigor.
*There is no mention of the raw data obtained from laboratory experiments or how it was used to validate the simulations.
*The conclusions focus too much on reafirming the methods used and error values but do not sufficiently explore the potential future applications of the model or implications for other tipes of asphalt mixtures.
Comments on the Quality of English LanguageThe English could be improved to more clearly express the research.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript has been improved significantly. This is a good improvement and it looks good. Thanks you for your consideration related to my comments/edits/suggestions.
Reviewer 2 Report
Comments and Suggestions for AuthorsCoatings-3331852R1:
A good revision was made to the paper.
Comments on the Quality of English LanguageThe English could be improved to more clearly express the research.
