Mitigation of Urban Heat Island Effects by Thermochromic Asphalt Pavement

Round 1

Reviewer 1 Report

Authors have presented a study of asphalt surface coatings using functionalized material to improve the reflectance of the asphalt concrete pavement. This was aim at providing possible solution to the urban heat island that is usually compounded by dark surfaces such as roofs and pavement.
The idea is sound and relevant. The manuscript is concise and to the point. Most necessary experiments were conducted to achieve the research objectives.

However, there is an important safety test that is missing from this study: the surface friction test. How does this coating affects surface friction of the pavement. Because any significant drop in surface friction could easily results in more accident tendency. Authors should provide some result on how the coating are not a problem when it comes to surface friction. 

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Before making any recommendations for an interesting scientific article "Thermosensitive Asphalt Pavements: Mitigation of Urban Heat Island Effects by the Functionalization with Thermochromic Microcapsules", I would like to present the following statements on the topic. Based on my long-term research and transfer profile in the field of holistic perception of the issues of municipality engineering, transport structures especially pavements I consider the evaluated scientific article to be extraordinary topical. Personally, I consider the dominant using of asphalt pavements in built-up areas of residential units to be inappropriate, precisely from the aspect of Heat Island Effects.

In order to improve the contribution enabling its rapid publication in a  renowned scientific journal Coatings, I would like to recommend incorporation of the following mandatory and facultative requirements to the authors, respectively, a credible justification for their non-implentation into  revision of reviewed article.

Mandatory requirements:

LNSA (Line Number of Scientific Article) 19...Road pavements are usually dark and, consequently, have a low albedo... Due to the fact that many readers not working in the described issue, and reading only the abstract,  not know the exact meaning "albedo", I recommend its brief explanation (e.g. Albedo is  measure of the reflectivity of material surface).

LNSA 26-27...Why does the scientific term Fourier Transform Infrared Spectroscopy have an abbreviation (FTIR)?

LNSA 85-88…The studies concern the temperature variation control and the reduction of the energy absorption by the pavement, once high temperatures contribute to the permanent deformation process of the asphalt pavements, and the low temperatures are associated with cracking and ice formation [1,26–28]…The article lacks an overview of air temperatures, from which the temperature ranges of road surfaces result. For example, in the article: Evaluation of the Effect of Average Annual Temperatures in Slovakia between 1971 and 2020 on Stresses in Rigid Pavements. Land (2022). The article presents a credibility correlation dependencies of air average annual temperature (Ta), maximum daily air temperature (Td,max) from altitude above sea level (m) of the surroundings of pavements. Based on the statistical evaluation of the subject air temperatures from 1971-2020, the following facts were objectified. The average temperatures range for altitude 0-1000 m were for Ta of 11.2 to 3.9 °C and Td,max 42 to 26 °C.

LNSA 209...transmittance...it is necessary to briefly explain the given term, which will allow a better understanding of Figure 5. FTIR spectra (recommended name change, see LNSA 265).

LNSA 265...3.3. SEM and EDS...I recommend not to use subsection names consisting only of abbreviations, the recommendation applies to the entire document.

LNSA 357-358 … Conclusions. This article was devoted to developing a functionalization coating with TM able to help to reduce the UHI effects aggravated by the dark coloration of asphalt pavement...In the article, it is desirable, at least in outline, to indicate the potential of the described innovative technology to reduce the temperature of the asphalt pavement surface and its immediate surroundings.

Facultative recommendations:

LNSA 2-4...Thermosensitive Asphalt Pavements: Mitigation of Urban Heat Island Effects by the Functionalization with Thermochromic Microcapsules... I would like to recommend to the authors a slight modification of the title of the reviewed scientific article. The term Thermosensitive Asphalt Pavements does not appear directly in the entire article, apart from its title. Also, the length of the title of the article, in the context of its content, seems to me to be beyond standard. For that reason, I would personally use, for example, the name: Mitigation of Urban Heat Island Effects by Thermochromic Microcapsules on asphalt pavement surface  (please take it only as an inspiration).

LNSA 97-99... Albedo is the fraction of solar energy received by the Earth that is returned scatteredly to space and ranges from 0 (100% absorption and 0% reflection) to 1 (0% absorption and 100% reflection) [31–33 ]....I personally consider the following definition of albedo taken from the English Wikipedia to be more accurate.  Albedo is the measure of the diffuse reflection of solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body that reflects all incident radiation. I recommend the authors to state their recommended definition of albedo for the issue of road pavements, especially urban asphalt pavements, described by them. 

INSA 185...(ASTM D'3319-97)...it would be appropriate to add the above-mentioned Standard to the references, or at least to provide its identification data in more detail in the text.

LNSA 264… Figure 6. Thermal Differential test… I recommend the authors to consider a significant expansion of the title, including an explanation of the abbreviations used, which will increase the self-explanatory nature of this figure.

LNSA 288-290… By comparing the SEM micrographs of sample AM with AM+T and AM+D, it is possible to visually notice that there is a change in their surface and the substrate became less visible due to the functionalization layer...For experts not working directly in the described issue, it would be appropriate to explain "is possible to visually notice" in more detail. It should be considered whether it would not be appropriate to highlight some details of the micrographs representing the surface differences in question.

LNSA 305-306… Thus, the SEM and EDS tests show the changes that functionalization leads to on the 305 surface of the bituminous mixtures, especially in AM+T+D+R. A... In the context of the article, is it correct to use term bituminous mixtures or asphalt mixtures?

I consider the scientific potential of the reviewed, for me  inspirativescientific article to be considerable and, despite the mentioned comments, I recommend its revision. From the aspect of the stated fact , based on a detailed study and high inovative, environmental of this paper  potential into the field to improve Urban Heat Island, in case of incorporation of comments, or relevant justification of their non-incorporation, I am able to process a repeated review within 3 days.

Author Response

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Author Response File: Author Response.pdf