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  • Fabricio Leiva-Villacorta 1,* and
  • Adriana Vargas-Nordcbeck 2

Reviewer 1: Anonymous Reviewer 2: Anonymous Reviewer 3: Konstantina Georgouli

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. Please note. The plagiarism rate is as high as 72%, please reduce it to below 15%.

2. There are too few references.

3. Reference not cited correctly.

4. Should 30.5 in Table 7 be 30?

5. There are too few keywords and they are not appropriate.

6. The 19mm data in Figure 3 exhibits significant dispersion, please provide further explanation.

Comments on the Quality of English Language

Extensive editing of English language required

Author Response

An Extensive editing of English language was conducted by the authors to make the document clearer and easier to follow. In addition, a professional in communication and U.S. native provided a final revision.

  1. The main source of duplicated content is the report submitted to the sponsor that can be obtained from the following link https://www.dot.state.mn.us/materials/dps/publications.html
  2. several new references were added to enrich the background.
  3. All the references were revised for proper citation.
  4. The value was corrected to 30, thank you for that comment
  5. Three more keywords were added
  6. The following statement was included in the document "

    As observed in Figure 1, 19.0 mm specimens had higher surface texture and overall higher density variability that contributed to the higher dispersion in Figure 3."

 

Reviewer 2 Report

Comments and Suggestions for Authors

This was an interesting study that needs to be further elaborated.

1_ Please improve the introductory background and enrich with relevant references that are now very limited.

2_ Please refine the objective statement and include a methodological flowchart.

3_ In the results, provide discussion points and comparative issues with past studies in order to highlight the original contribution of the current study.

4_ Please add new references and conform to the required format.

Comments on the Quality of English Language

Moderate changes are needed.

Author Response

An Extensive editing of English language was conducted by the authors to make the document clearer and easier to follow. In addition, a professional in communication and U.S. native provided a final revision.

  1. Several references with relevant information were added in the in the introduction to enrich the document.
  2. The objective was refined and included at the end of the introduction section.
  3. This is the first study that was conducted to obtain the precision statements and that was the original plan of the sponsor.
  4. See response to point 1.

Reviewer 3 Report

Comments and Suggestions for Authors

The paper deals with the repeatability and reproducibility of the data concerning pavement density. It is important to set this standards and to this end the paper's conceptual idea is interesting. There are some issues that need to be addressed. My comments are the following.

 1. The objective of the paper is not clearly stated. I suggest to add a paragraph at the end of the Introduction to clearly state the aim and objective of the paper.

2. The method followed needs to be further supported and explained. Why did you perform laboratory tests? The scope of the DPS is to convert dielectric data to density without coring field cores. 

3. More information on the sensors used for laboratory and field testing are needed.

4. Are the mixtures prepared in the laboratory similar to the mixtures in the field? 

5. In Figures 2-5 and 8-11 the legend needs to be defined (what does 195, 206, ... stand for?)

6. On page 10, line 262 "Figure 12a shows bar plots of SR and SR values computed" SR appears twice. I believe it should be Sr and SR.

7. On page 10, line 268 instead of Figure 6 it should be Figure 12.

8. My main concern is that many sections are not adequately explained and analyzed. The abstract contains information that are not mentioned or further analyzed in the main text. For example in the abstract authors state "However, when converted to density, the statements were significantly  below the reported statements for Bulk Specific Gravity and Vacuum Sealing in the laboratory, and Nuclear and Electromagnetic density gauges in the field." Were these methods used in the frame of this research?

Author Response

  1. The objective was refined and included at the end of the introduction section.
  2. Laboratory tests are part of the AASHTO protocol to obtain a correlation between density and dielectric values.
  3. All the sensors were developed by the same vendor. Each sensor serial number was included in the plots and mentioned within the body of the document.
  4. All the mixtures were plant produced lab compacted mixtures to account for the variability during production.
  5. It was stated in the revised version that each number 195, 206, etc. represents the serial number of the sensor as a form to identify each sensor.
  6. Figure 12 shows Sr and SR in the revised version.
  7. Text was corrected to show "Figure 12"
  8. An Extensive editing of English language was conducted by the authors to make the document clearer and easier to follow. In addition, a professional in communication and U.S. native provided a final revision.

 

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

None.

Author Response

No comments were provided in this second round of revisions.

Reviewer 3 Report

Comments and Suggestions for Authors

The Materials and Methods section should be more analytical and detailed. Specimen preparation, filed testing and measurement apparatus must be thoroughly discussed and presented. Specific comments are the following:

1.      Line 149-150: “In this context, each sensor or antenna was treated as an independent laboratory”. To measure what. It should be clearly stated that dielectric constant measurements are made.

2.      Line 150-151: “evaluating laboratory precision with a total of nine sensors”. Please describe the sensors characteristics. For example their frequency. Why are they considered as different laboratories. What are the differences between them? How is this in accordance with the reproducibility as stated in the Introduction (considers the variability of results when the testing conditions change from one laboratory to another. This includes differences in operators, equipment, and environmental conditions, which usually contribute appreciably to the variability of the test results).

3.      Line152. How were the specimens compacted? Later on it is referred that the Superpave Gyratory compactor was used. Which standard was followed. What was the final height of the specimens?

4.      Line 155. Three readings (centered, rotated and flipped over). Centered where? At the top of the specimen? At the middle of the specimen in the vertical direction? Maybe a figure would help the reader to gain a better understanding of the measurement method.

5.      Line 162. Which thickness do you refer to? It should be clearly stated.

6.      Were there any surface defects that could interfere with the measurements?

7.      Table 2. Which of the sections are fine graded and which are open graded?

8.      Line 185-187. The air void and thus dielectric constant variability is well known especially for coarse graded mixtures compacted with the gyratory compactor. It is proven that higher air voids are concentrated at the top and bottom platens due to the restrictions on the plates. This can be avoided by cutting the top and bottom of the specimens by a few mm. Was this considered in the study? Would this have an impact on the results and conclusions?

9.      Line 196-197 “These critical values vary depending on the number of laboratories used (or, in this case, 196 the number of sensors) and the number of replicates”. Is the number of the measurements in each replicate (three in this case) a dependance factor as well? Would that change the critical values?

10.   Lines 207-210. “It was observed that 19.0 mm samples had significantly higher reproducibility standard deviations at lower dielectric values. This increase in variability can be attributed to both the overall higher variability in the results from the 19.0 mm samples and the increased variability observed at high air void levels”. How is this statement drawn from figure 6? Which are the values corresponding to 19.0mm samples?

11.   Figure 6. The range of the standard deviations in the y axis is up to 0.05. Shouldn’t it be up to 0.10 according to Figure 3. Does this figure show the relationship between standard deviations (as in figure 3) and dielectric measurements (as in figure 2)? Are all data presented in this figure or just those corresponding to 9.5 mm samples?

12.   Table 3. Please define the equations form which the density was estimated.

13.   Line 233. Please explain what does HDPE stand for.

14.   Did you perform any equipment consistency verification prior to the laboratory testing?

15.   Line 345. Please replace 30.5m with 30m

16.   Lines 358-359. How are these values compared to the statements shown in table 1?

17.   Line 368 “Preliminary laboratory conversions of dielectric values to air voids”. Did such a conversion take place in the framework of the present research.?

18.   In the introduction it is stated that “The study also focused on breaking the measurement errors down into their components and estimating the error propagation impact on the final DPS evaluated in-place pavement density”. No mention is being made in the conclusions about this. I believe that this is not part of this research. The research is focused on explaining possible reasons for variations which is far from error components and error propagation. The statement should be revised to clearly state the undertaken work.

Author Response

Please see the attachment

Author Response File: Author Response.docx

Round 3

Reviewer 3 Report

Comments and Suggestions for Authors

I would like to thank the authors for addressing my comments. There are just a couple of clarifications.

1. Lines 155-159. "These mixtures were compacted with a Superpave Gyratory compactor at four density levels: High (H) = 97%, Medium High (MH) = 94%, Medium Low (ML) = 91%, and Low (L) = 88% of the maximum theoretical density (Gmm). Each compacted sample was  compacted at 75 gyrations to the Superpave design size of 115 mm (height) by 150 mm (diameter)." If all specimens were compacted at 75 gyrations  with the same target height, how were the different densities accomplished?

2. Line 182. "Thickness: ranging from 3.8 cm to 13.9 cm". Replace thickness with asphalt layer thickness

Author Response

Thank you for your comments:

Comment 1: We did have to adjust the text in the document to show that samples were compacted to reach the 150 mm height by changing the weight of the design sample that was compacted at 75 gyrations.

Comment 2: the test was replaced to show "Asphalt Layer Thickness"