Effect of Weak Zones on Resilience of Sustainable Surface Course Mixtures of Fresh-Reclaimed Asphalt Pavement

Round 1

Reviewer 1 Report

I. Overall Evaluation • This research paper deals with the effect of weak zones (WZ) on the resilient modulus of mixtures of fresh asphalt with 20 % RAP. • The study demonstrates that 20/30 grade binder caused increase in MRT considerably for 0.1 sec load duration and 0.3 sec load duration while compared to other grade binders. • Weak zones (WZ) based on digital images of asphalt specimens are presented to assess the effect of orientation of surface course gravel particles on resilient modulus. • Experimental data is validated by factorial analysis. • Main objectives of this study are:

1. To determine the resilient modulus (MR) of asphalt mixtures prepared with different grade binders for wearing course gradations (like SP-A, 88 SP-B and MS-2) of fresh asphalt aggregate and 20 % reclaimed asphalt pavement 89 (RAP) mixture at different temperatures and load durations.

2. Validation of experimental data by statistical analysis.

3. Image analysis to view orientation of aggregate particles of fresh asphalt and RAP anddetermination of weak zones. 

 

II. Technical Quality and Originality

 

• Technical content is good • Detailed explanation of work is done.

 

III. Organization and clarity of language

 

• Organization of the work is systematic except for some minor corrections. • Equation 1 is missing. • Equation 2 has to be Center tabbed. • Uniformity in size of tables and figures is not followed. • Some figure descriptions are left aligned and some are center aligned. • Table 4 columns are not aligned properly.

 

IV. Results and Conclusion

 

• Figure 7 description is not clear. • What is the inference from figures 7, 8 & 9 is not explained. • Placing of figure 11 is not appropriate. • Sizes of the figures 12 & 13 have to be reduced. • Conclusion discussion is clear and up to the mark.

Author Response

Thank you very much for valuable comments and suggestions for the improvement of the article. Response is attached. 

Author Response File: Author Response.pdf

Reviewer 2 Report

This manuscript presented a research on the effect of weak zones on the resilience of the fresh asphalt-RAP mixtures, However, the current research status on the effect of weak zones on the resilience of the asphalt mixtures is not properly cited and discussed. In the context, the authors only used the IDT test to evaluate the resilience of the asphalt mixture, which was biased and insufficient.

1. What is the main question addressed by the research? This research wanted to address the effect of weak zones on the resilience of the mixture of fresh asphalt and reclaimed asphalt pavement (RAP) by using binders with different grades. 2. Is it relevant and interesting? The authors did not clearly present the relevance in the manuscript. 3. How original is the approach? The approach is conventional. 4. What does it add to existing publications on related topics? It showed that the usage of 20/30 grade binders might increase the resilient modulus of the asphalt mixture. 5. Is the paper well written? The paper needs English editing service. 6. Are the conclusions consistent with the evidence and arguments presented? The conclusions cannot be fully supported by the experimental results and discussion.

Author Response

Thank you very much for valuable comments and suggestions for the improvement of the article. Response is attached. 

Author Response File: Author Response.pdf

Reviewer 3 Report

The paper shows effect of weak zones in mixture to resilient modulus results. Unfortunately, it lacks the rigor expected in an international publication.

L 23 grammar: the relation of WZ to the total

The testing is standard and you don’t need to include photos; remove figures of instrumentation

L45 avoid repetition

L51fresh asphalt fresh asphalt-RAP mixtures?

L61 don’t use diseases for  pavement use distress. Diseases is for humans or animals

Correct grammar: Increasing load duration to double value will cause

L 76nominal aggregate size to nominal maximum aggregate size

These gradations might be well known to some but not all readers. Please explain these

L98 grammar: mixtures for study of resilience of asphalt mixtures

quantified as 3.8% of what?

Define VA aggregate

L105 what do you mean by tests like? Did you do other tests?

L150 what is seating force?

Fig 6 are the upper and lower limits for all three mixtures? What was your motivation for choosing the three mixtures?

How repeatable are fig 7-9? Are these single measurements? Which binder was used in fig 7 and 8?

Please give information about the binder and aggregates in RAP.

Table 4 what is ABC? Define all variables in caption. Need to improve description of table 4 significantly

Materials and method and results: add heading with test method and materials. State clearly which mixtures are with RAP.

Fig 13 what are the blue and red lines? Your 10x and 20x magnifications show the same information why do you need both? How do you define weak zones? expected cracks?

L282This sentence is not justified from the results presented: WZ fall in the order of SP-B < MS-2 < SP-A which validates the  evaluated resilient modulus. There is no justification for this statement: area of WZ decreases. You need to do a more rigorous analysis using image analysis techniques that is lacking here. You can only mention that this is an observation on a limited number of samples. You actually showed one sample.

L286 How did make this conclusion: the resilient modulus of asphalt mixtures  increases due to increase in grain-to-grain contact of gravel particles

Typo: Presented in Figs. 14 to 17 present the

Fig 14-17 again how did you define area of weak zone, how many samples did you measure? What do you mean by total resilient modulus?

Add error bars to all figures where relevant. State how many repetitions.

Where are the IDT results?

 

Author Response

Thank you very much for valuable comments and suggestions for the improvement of the article. Response is attached. 

Author Response File: Author Response.pdf

Reviewer 4 Report

The paper is well structured and is interesting. Even so, the reviewer believes that such large differences in resilient modulus shown in Figure 10 should be justified in detail. In addition, it should be clarified how the % of weak zones has been estimated to build figures 14, 15, 16 and 17.

As minor items, highlight the following:

- Figures 1, 3, 4 and 5 have poor quality. They must be improved.

- Reference formulas 2 and 3.

Author Response

Thank you very much for valuable comments and suggestions for the improvement of the article. Response rebuttal is attached. 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Necessary changes had been made hence accept the paper

Author Response

Thankyou very much for your valuable input in the improvement of the manuscript quality. 

Reviewer 2 Report

The authors have made good improvements in the manuscript. However, a few modifications can be implemented to polish it further.

(1) In page 15, line 305, the influences of the grades, gradations, and load durations on M_RT can be expanded and depicted more detailly.

(2) In the conclusion part, the correlation between the grades and weak zones should be specified, and the applications of the findings proposed in this manuscript in pavement must be addressed.

Author Response

Sr.	Reviewer Comments	Authors Response	Remarks
1	In page 15, line 305, the influences of the grades, gradations, and load durations on MRT can be expanded and depicted more detailly.	The influences of grades, gradations and load duration on MRT was expanded and depicted with more details in the paper.	Comments Incorporated.
2	In the conclusion part, the correlation between the grades and weak zones should be specified, and the applications of the findings proposed in this manuscript in pavement must be addressed.	Conclusion Sr. No. 4 was added about the correlation between the grades and weak zones. The applications of the findings in pavement have been addressed also.	Comments Incorporated.

Author Response File: Author Response.docx

Reviewer 3 Report

The hypothesis of the paper in identifying weak zones in mixture and relating them to performance is good, however the identification of the weak zones using microscopy is not convincing.

Author Response

We Authors want to Thanks to the Worthy Reviewer who appreciated the hypothesis of the paper. Regarding the use of microscopy for the identification of the weak zones, we appreciate all the Worthy Authors and Editor for making the content more meaning full through their precious comments. During finalization of scope and methodology, for the determination of weak zones of asphalt mixtures, we have two options: 1. Scanning Electron Microscope (SEM) – micro to nano level 2. Optical Microscope – macro to micro level Optical microscopy was adopted for this study as our scope was more towards the macro to micro level. However, observation of the Worthy Reviewer is still well noted. An effort has been made through the addition of some more elaborations to make the aspect more convincing in the revised/final draft.

Author Response File: Author Response.docx

Reviewer 4 Report

The required suggestions have been corrected. Ths reviewer´s opinion is that paper is suitable for publication in its current version.

Author Response

Thankyou very much for your valuable input in the improvement of the manuscript quality.