Comparison of Potential Contribution of Typical Pavement Materials to Heat Island Effect
Round 1
Reviewer 1 Report
I appreciate the authors efforts in conducting this research and putting together the manuscript. The manuscript is overall well-written, and the research methodology is scientifically sound. The figures' quality is acceptable and the results have been fairly well presented and discussed. The results support the conclusion.
Author Response
Thank you very much for your approval of this study.
Reviewer 2 Report
Review comments on "Comparison of potential contribution of typical 2 pavement materials to heat island effect."
This topic has been widely discussed as foundation work for the heat mitigation measures (pavement materials and internal structures, coating materials. etc,) applied to the paved road around the globe. Therefore, this is nothing new to the rank of the UHEI potentials among three convenient paving materials. Also, the way the test results are collected and interpreted contains some errors that could affect the results. Below are the specific comments the authors should consider:
Line 75: Specific mixture conditions (concrete (C25, P.O 42.5), a porous asphalt mixture (PAC13, 90#, 20%) and a dense asphalt concrete (AC13, 90#)) must be elaborated as they are critical contributors to the temperature absorption characteristics.
Line 106: The heat transmission from the surface to the bottom of the sample is predominantly affected by heat conductivity and heat diffusivity of paving materials. Both properties would change with the boundary conditions. In particular, the normal heat diffusivity that occurs in pavements can be greatly hampered by the thermally insulated wraps, escalating the temperature increase. In order to minimize this interference, sample sizes (dimensions) need to be designed based on some thermal analyses.
Line 112 A heat radiation from the Sun was measured for a day but its daily variations were not accounted for. The impact of solar radiation would be much greater than air temperature changes and will depend on the daily cycles during warm days. A difference between solar radiation and air temperature could be significant even in the daytime. The authors need to explain why the test was done only for a day, not weeks or months, to capture this long-term effect.
Line 149: It would be quite puzzling if the temperatures at different depths are different when the underlying layer conditions are considered. Depending on the aggregate structural and moisture conditions in base or subbase, the temperature changes tremendously for larger voids as in porous asphalt pavements.
Line 154 Please elaborate on the heat capacity. The statement from Line 154 to Line 162 is incomplete to explain the heat continuously emitted from the pavements even after the Sunsets.
Line 180: The solar radiation needs to be investigated in a larger time scale, As a result, the correlations the testing variables might be either weaker or stronger than presented.
Line 188: What do the COPPEL in Table 2 and HIP in Equation 2 stand for? All acronym must be explained before use in the text.
Line 230: The accumulated HIP needs to be investigated over a longer period of time to factor in the daily fluctuations of thermal indicators.
Line 293: In line 283, the authors mentioned “The heat absorption and heat release rate of dense asphalt concrete is the fastest among the three materials.” But in Line 294, it says “the order of heat release capacity is C25＞AC13＞PAC13.” It is contradicting to what it said in Line 283. Any description of the rank of Q storage?
Line 298: Broadly speaking, it is true that the surface temperature is the most sensitive to the climatic conditions including air temperature and solar radiation. But as a scientific paper, this needs to be rigorously tested under various possible scenarios over a longer time period. This paper mentioned those possible drivers (radiation, conductions, and convection) behind the UHIE, but it lacks in detail and evidence that supports the individual contributions.
Line 314: The HIP predictions coincide with conventional observations in the field. In fact. porous pavements (both asphalt and cement concrete) are designed to cool the surface of roads. So, it is not surprising to see the presented ranking. The authors should have gone deeper than this and offered better insight into this phenomenon with well-designed experiment programs.
Author Response
Thanks for the encouraging and constructive comments. All comments have been carefully reviewed and addressed in the revised paper and responded one by one.
Please see the attachment
Author Response File: 
Author Response.pdf
Reviewer 3 Report
The manuscript presents a very interesting topic and concerns The The urban heat island effect. Environmentally friendly technologies and counter-measures of global warming are one of the most important challenges in the global economy.
The subject matter is within the scope of the journal The methodology is sufficiently well explained that someone else knowledgeable about the field could repeat the study. Each figure and table is necessary to the understanding of the conclusions. All elements of the manuscript relate logically to the study's statement of purpose. The work is well written but needs some adjustments.
Some suggestions for improvement are given as follows:
- Introduction:
In the introduction, the authors indicate the problem of global warming. Currently, construction materials and road construction technologies must comply with the principles of sustainable development. So the authors should extend the introduction to other environmentally friendly production technologies.
Recommended articles in this range:
Recycling of marble waste: A review based on strength of concrete containing marble waste. Journal of environmental management, 2019, 231, 86-97. https://doi.org/10.1016/j.jenvman.2018.10.034
Application of zeolite tuffs as mineral filler in Warm Mix Asphalt, Materials, 2020,13(1), 19, DOI: 10.3390/ma13010019
Influence of waste engine oil addition on the properties of zeolite-foamed asphalt, Materials, 2019, 12(14), 2265, https://doi.org/10.3390/ma12142265
- Materials and Methods
What materials and proportions were used to make cement concrete, porous asphalt mixture and asphalt concrete? At what temperatures were the mix asphalts compacted? - Complete this information
Delete Figure 1 - These are standard samples.
Delete Figure 3 - Temperature measuring instruments have no scientific justification
- Results
Tasks regarding thermal conductivity, the heat capacity and the reflectivity require discussion and more extensive analysis.
- Conclusion
- The conclusions relate to conducted research, they do not require improvement.
I hope that the feedback I provided should be useful for authors.
Comments for author File: Comments.pdf
Author Response
Thank you very much. The authors sincerely thank all reviewers for their encouraging and constructive comments. All comments have been carefully reviewed and addressed in the revised paper or responded one by one.
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The reviewer can see some improvements in the revised manuscript. In the response note, the authors have addressed the comments and concerns over the scope and conditions of the experiments. But it still lacks some important information. such as asphalt binder properties and volumetric properties (e.g., binder contents percent binder by volume of the mixture), air contents, VMA, VFA, etc.), which may be linked to the heat conductivity and diffusivity of asphalt mixtures. For instance, binder types and amounts may have to do with heat absorption and emission at different temperatures. This may explain the short-term UHIE of materials in depth.
Unless there are some novel findings based on extensive investigations, this manuscript does not carry any significant values because the ranking of the HIP of three materials is nothing new. Further, although the intention of authors is understandable, the long-term characterization of UHIE that can account for the effect of various climatic events is critical to confirm it as a reliable indicator for the HIP.
Author Response
Thanks for the encouraging and constructive comments. All comments have been carefully reviewed and addressed in the revised paper and responded one by one.
Please see the attachment
Author Response File: Author Response.pdf
Reviewer 3 Report
The subject matter is within the scope of the journal. The methodology is sufficiently well explained that someone else knowledgeable about the field could repeat the study. Each figure and table is necessary to the understanding of the conclusions. All elements of the manuscript relate logically to the study's statement of purpose.
Author Response
Thank you very much for your approval of this study.
Round 3
Reviewer 2 Report
As the authors acknowledged in the response letter, the contributions of the tested materials to the index development have been discussed in other research and thus have little scholarly values added to the literature. If the long-term evaluation is easy to obtain (as the authors claim), it is wiser to get the data and make this work publishable because it would make an impact. Unless this happens, my overall recommendation should be the same.
Author Response
This research is based on the analysis of the relationship between the pavement structure temperature, surface temperature, air temperature and solar radiation to study the impact of different materials on the Urban Heat Island Effect. This is a data-based analysis method with solid experimental procedures. Our proposed index HIP includes the influence of two environmental parameters, air temperature and solar radiation intensity. We consider HIP a comprehensive index, which is more valuable than the single analysis of the thermophysical parameters of the material. It is obvious that long-term measurement of the surface or internal temperature of pavement materials and air temperature is not a very difficult technology. However, the impact of various uncertain factors in the long-term monitoring of the project needs further analysis. The work of this paper has formed a preliminary conclusion under the limited conditions of the experiment. Long-term project monitoring is not achieved overnight.
