The Use of Vacuum Residue as a Potential Rejuvenator in Reclaimed Asphalt Pavement: Physical, Rheological, and Mechanical Traits Analysis

Round 1

Reviewer 1 Report

This paper investigates the effect of vacuum residue (VR) rejuvenator on the performance of recycled asphalt and recycled asphalt mixes, and evaluates the economic benefits of recycled asphalt mixes compared with virgin asphalt mixes. The study is very informative and the main comments are listed below.

（1）The author needs to provide additional information on the number of parallel experiments in different test groups and add error lines to the results graph.

（2）It is recommended to supplement the production process of recycled asphalt mixture. For example, the heating temperature of the material, the forming temperature of the specimen, etc.

（3）In Figure 3 and Figure 4, the line thickness of the VA group is different from that in Figure 2, it is recommended to unify the drawing mode.

（4）In the economic benefits section, it is recommended to further consideration of the transportation costs in each stage, and explain the various components of the cost composition of recycled asphalt mixture （10.1016/j.conbuildmat.2022.130054, 10.3390/buildings12071057）. In addition, if the authors have not considered the impact of this component, additional explanations need to be provided in the paper.

None

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Please consider and correct some remarks related to some lines as mentioned on the manuscript attached below for Lines (32,100,198,199,200,228).

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

This paper analyses the feasibility of using VR with the aim of improving the properties of bitumens and bituminous mixtures with 40% RAP. The proposal would contribute to decrease of bitumen consumption in order to obtain environmental and economic benefits. The paper is well structured and working plan covers most relevant properties. However, it would be important to let the authors know my comments and ask them to answer the following questions in order to accept the paper for publication:

Line 138: why do authors say that penetration is 160 dmm?

Line 258: PVN is this parameter the same as penetration index?

Section 4, lines 157-188: How many replicates were manufactured for each test? A statistical analysis should have been carried out to confirm the significant differences.

Lines 316-317: the difference could be due to dispersion of results or due to the modification caused by VR in the aged asphalt. What is the standard deviation in the results of this test?

Line 364: what is R100?

Section 5.7, lines 375-390: Maximum particle loss percentage is an important limit used in other countries to design permeable mixtures. I would like to know if these mixtures have a specified limit according to local specifications.

Cantabro test is used in some European countries to design porous asphalt but not for mixtures with a low air void percentage, as in this case. Also, the test is usually performed at 25ºC. When the test is carried out at different temperatures, it is called UCL method. This paper could be considered as a reference:

Valdés, G., Miró, R., Martínez, A., & Calabi, A. (2014). Effect of the physical properties of aggregates on aggregate-asphalt bond measured using the UCL method. Construction and Building Materials, 73, 399-406.

 

Section 5.8, economic analysis: the comparison is interesting and a good indicator but it must be kept in mind that no LCA has been conducted and the assumption that similar service life will be obtained with the mixtures compared has been made.

Author Response

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