Modelling the Environmental and Economic Life Cycle Performance of Maximizing Asphalt Recycling on Road Pavement Surfaces in Europe
Round 1
Reviewer 1 Report
This manuscript presents a modelling the environmental and economic life cycle performance of increasing asphalt recycling on road pavement surfaces in Europe. This approach seems promising and is of practical application value. The manuscript is well written and I do not see anything that needs to be revised.
A minor problem is the formatting of the text (Error! Reference source not found.) but this does not affect the substance of the publication.
Author Response
Thanks for the comments. The format error, when found, have been solved.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Title: Modelling the environmental and economic life cycle performance of increasing asphalt recycling on road pavement surfaces in Europe
Comments:
· Abstract:
Abstract is vague. Make it short.
· Key words:
Give the full forms of LCA; LCC.
· Highlights is not necessary as per the journal guidelines.
· This manuscript is not prepared with sustainability template,
· The word Error! Reference source not found is found at many places. Remove it.
· Fig.3 should be replace with an enhanced quality of images so that the text in the figure is readable
· How your work differs from the past work?
· In the unit L/m2, the square value should be at superscript. Do the same corrections throughout the manuscript
· Don’t numbering like 1). 2), 3) within the main text because the number 1, 2 are already assigned for introduction etc..
· The Presentation of manuscript could be better. In the present form, the organization of manuscript is poor.
· Conclusion should be presented with the research recommendations clearly
This Work ‘Modelling the environmental and economic life cycle performance of increasing asphalt recycling on road pavement surfaces in Europe’ requires major revision.
Regarding language, Minor editing is enough
Author Response
- Abstract: Abstract is vague. Make it short. Thanks for the suggestions, the abstract lenght was reduced.
- Key words: Give the full forms of LCA; LCC. Thanks for the suggestions, the keywords were changed to the full form and the acronyms left into brackets
- Highlights is not necessary as per the journal guidelines. Reply: Thanks for the suggestions, The highlights were deleted.
- This manuscript is not prepared with sustainability template. Reply: Thanks for the suggestions, the paper was adapted to the MDPI template.
- The word Error! Reference source not found is found at many places. Remove it. the links to sources were updated
- 3 should be replace with an enhanced quality of images so that the text in the figure is readable. Thanks, the figure 3 was substituted with image 3, 4 and 5 and now they are more readable.
- How your work differs from the past work? The paper shows an application of life cycle techniques to assess the environmental and economic sustainability of high content RAP asphalt mixtures. The authors aim at evaluating whether maximizing reusing of asphalt mixtures in wearing courses makes sense within Europe.
- In the unit L/m2, the square value should be at superscript. Do the same corrections throughout the manuscript.The unit was corrected
- Don’t numbering like 1). 2), 3) within the main text because the number 1, 2 are already assigned for introduction etc.. The numbering 1), 2) within the main text was deleted
- The Presentation of manuscript could be better. In the present form, the organization of manuscript is poor. The authors did their best to improve the paper.
- Conclusion should be presented with the research recommendations clearly. Thanks for your suggestion. Conclusions were deeply revised to be used by researchers and practitioners.
Author Response File: Author Response.pdf
Reviewer 3 Report
This study aims to model the environmental and economic life cycle performance of increasing asphalt recycling on road pavement surfaces in Europe. The topic is very interesting and have added value to literature. However, there are some issues that need to be addressed before consideration for publication.
Abstract
The abstract needs to be improved. The first sentence in the abstract, it is necessary for the authors to add a sentence to describe the problem or motivation to focus on this topic. The second sentence should provide the literature gap. In the third sentence, the authors should say what they are doing, and then provide the empirical findings. Finally, the significance of the finding should be offered. Authors should remove the numbering style 1), 2), and 3) from the abstract and put the contribution in the abstract.
Introduction
-I suggested authors to draw the steps of LCA as Figure instead of writing it as bullet. Same suggestion is applied to the steps of LCC.
-In addition, the research questions of this paper are unclear. Please adjust the structure of the Introduction to highlight the research gaps, questions, objectives, and contributions.
Methodology
-I suggested authors to remove the section 2.1 from the methodology section and make it as a separate section.
-I suggested authors to replace Table 2 by a Figure to show each asphalt geometry.
-There are a lot of writing in the section 2. I suggested to put more Figures instead of writing.
-I recommended numbering style to be limit to three levels at max instead of five levels.
-I recommended authors to polish their English writing through the manuscript.
Conclusion
-I suggested authors to highlight the main contributions of their study.
-Authors should indicate the limitations of their study along with those of their proposed methodology.
-the findings of their study should very brief instead of long sentence
References
-references are not completely written. In some, there is no issue, volume. Please check them carefully and I suggested to use new references instead of old ones.
The English writing must be improved
Author Response
Abstract
The abstract needs to be improved. The first sentence in the abstract, it is necessary for the authors to add a sentence to describe the problem or motivation to focus on this topic. The second sentence should provide the literature gap. In the third sentence, the authors should say what they are doing, and then provide the empirical findings. Finally, the significance of the finding should be offered. Authors should remove the numbering style 1), 2), and 3) from the abstract and put the contribution in the abstract.
Thanks for the suggestions. The abstract was reviewed accordingly.
Introduction
-I suggested authors to draw the steps of LCA as Figure instead of writing it as bullet. Same suggestion is applied to the steps of LCC.
Thanks for the suggestions. Using bullet points allows the explanation of the content of each step and for this reason it was considered the best choice.
-In addition, the research questions of this paper are unclear. Please adjust the structure of the Introduction to highlight the research gaps, questions, objectives, and contributions.
Thanks for the suggestions. The introduction was deeply revised accordingly.
Methodology
-I suggested authors to remove the section 2.1 from the methodology section and make it as a separate section.
Thanks for the suggestion. We understand your point, but our aim is to guide the reader in accordance to the legend presented in figure 2.
-I suggested authors to replace Table 2 by a Figure to show each asphalt geometry.
The table was reduced in content. Instead, the pavement representing the pavement structure was added.
-There are a lot of writing in the section 2. I suggested to put more Figures instead of writing.
Thanks for the suggestions. The authors are aware that section 2 is full of information. Figures and tables were added when possible, but there are some contents which need to be explained with the use of the text.
-I recommended numbering style to be limit to three levels at max instead of five levels.
Thanks for the suggestions. Some changes were made to make the document more readable.
-I recommended authors to polish their English writing through the manuscript.
Thanks for the suggestions. The paper was completely reviewed under this point of view.
Conclusion
-I suggested authors to highlight the main contributions of their study.
-Authors should indicate the limitations of their study along with those of their proposed methodology.
-the findings of their study should very brief instead of long sentence
Thanks, the conclusion were revised.
References
-references are not completely written. In some, there is no issue, volume. Please check them carefully and I suggested to use new references instead of old ones.
Thanks for the suggestions, the reference were reviewed and updated.
Author Response File: Author Response.pdf
Reviewer 4 Report
1. Abstract should be concise.
2.Aim of the study looking descriptive in nature. Make short
3.Line 131, why author selected 90% RAP and 60% RAP. why this particular RAP quantity
4.All RAP percentage taken here for just as the case study????
5.Fig 5/6 should be legible
6.For analysis , any software used? Specify
7.Here author has considered only CO2 emission. All other emission should be included
8.Table 6 on which basis cost for transport, electricity, heat decided
9.Section 3.3 may be included before Results and discussion section
Author Response
- Abstract should be concise. Thanks for the comment. The abstract lenght was reduced and now it’s more concise.
2.Aim of the study looking descriptive in nature. Make short. Thanks for the comment. Also the aim of the study was made shorter.
3.Line 131, why author selected 90% RAP and 60% RAP. why this particular RAP quantity. Thanks for the comment. This paper investigates the sustainability performance of six different mixtures, whose mix design and properties were validated by other researchers involved in the same project. The aim was to investigate the properties at the increase of the amount of RA, whose percentage within each mixture varies from 0% (control mix) to the closest feasible amount to 100% RA, in a range of 30- 60- 90%.
4.All RAP percentage taken here for just as the case study???? Thanks for the comment. Yes, these mix designs with a high amount of RAP were just investigated from a theoretical point of view and not used for existing roads.
5.Fig 5/6 should be legible. Thanks for the comment. The figures were updated: colors were changed to make them more legible.
6.For analysis , any software used? Specify. Thanks for the comment. The environmental calculations were performed with asPECT (asphalt Pavement Embodied Carbon Tool), as mentioned in line 301, while the life cycle cost was performed with the support of RealCost software, provided by the FHWA, as reported in line 444.
7.Here author has considered only CO2 emission. All other emission should be included. Thanks for the comment. Thanks for the suggestion. As mentioned in the paper, the research is limited to a Carbon Footprint, hence only the amounts of CO2eq are calculated. The authors are aware that extending the number of impact categories can improve the quality of the study. This can be the object of a further publication
8.Table 6 on which basis cost for transport, electricity, heat decided. Thanks for the comment. The costs reported in the table, as mentioned from line 470, were mostly collected interviewing plant/contractor and materials suppliers: for SE case study all data is provided by Ferrara, except the the cost of fibers by Iterchimica, for NE and CE case studies the information were taken from literature (i.e. Wayman, 2014), excluded the costs of fibers (Iterchimica, 2015) and STORBIT PLUS additive (Storimpex, 2015). Electricity and oil costs were taken from literature (Wayman M. 2014).
9.Section 3.3 may be included before Results and discussion section. Thanks for the comment. The section “Results and discussion” was organized into three main points: the first two present with the calculations of the calculation of environmental and economic performances, the third one summarizes and comments the above-mentioned results. In the authors’ opinion it follows a logic structure.
Author Response File: Author Response.pdf
Reviewer 5 Report
The study presents the sustainable and environmental impact of maximizing the recycling of materials in asphalt mixtures. Three cases were developed to analyse and compare the environmental and economic performance of the high-content RA asphalt mixture. The author needs to take into consideration the impact of recycled materials on the durability of the produced asphalt mixtures. The authors also need to demonstrate the impact of maintenance on the traffic level, because the performance life of recycled pavements is lower than pavement made of virgin mixtures. Moreover, time and energy are required for milling and preparing the required aggregate to meet the specified gradation.
The study presents the sustainable and environmental impact of maximizing the recycling of materials in asphalt mixtures. Three cases were developed to analyse and compare the environmental and economic performance of the high-content RA asphalt mixture. The author needs to take into consideration the impact of recycled materials on the durability of the produced asphalt mixtures. The authors also need to demonstrate the impact of maintenance on the traffic level, because the performance life of recycled pavements is lower than pavement made of virgin mixtures. Moreover, time and energy are required for milling and preparing the required aggregate to meet the specified gradation.
Author Response
Thanks for the comments. The whole research is based on the fact that “if not technically feasible, then they’re not sustainable”. Hence, a main assumption is that the newly developed mixtures can be engineered to perform as well as the baselines. This is a main assumption and it must be at the base of any “more sustainable” option. Hence not under-performing is taken as a starting point. This assumption is also backed-up from the results obtained within the AllBAck2Pave Project: Laboratory results are available in publication and open repository (i.e: https://www.h-a-d.hr/pubfile.php?id=1137), as mentioned in the manuscript.
In a LCA study, the time variable is to be considered as a function of the energy consumed for a given activity, it has no weight of its own. In this study, energy required both for milling and for heating the RA was considered, as reported in paragraph 2.2.1.2 (LCI Inventory).
Author Response File: Author Response.pdf
Reviewer 6 Report
The presented paper is an interesting, practical and useful article for engineers in the field of recycled materials. It needs some editing (for example, two tables with number 2 have been provided) and it is necessary to explain the contents more briefly. It is better to use statistical analyzes to measure the reliability of the results.
Minor editing of English language required.
Author Response
Thanks for the comments. The numbers of the tables was corrected and their references in the text was updated. Some contents were summarised. Concerning the statistical analysis, for our experience in other study, the sensitivity analyses are a very powerful tool. It could be a good idea to perform a sensitivity analysis of durability
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
After carefully check the revised manuscript, I have seen that authors have significantly improved it and answered to my comments. Therefore, I suggest the paper to be accepted in its current form for publication
Minor editing of English is required.
Reviewer 4 Report
Author has incorporated all the response to comments reported by author. The manuscript may be accepted for publication.
