Proposed Cool Coatings with High Near-Infrared Reflectance and Heat Insulation for Asphalt Pavement

Kui Hu,Caihua Yu,Yuzhou Duan,Guixiang Chen,Yujing Chen

doi:10.3390/coatings11010085

Abstract

In summer, black asphalt pavement can absorb a considerable amount of solar radiation, which causes its temperature to rise. Heated asphalt pavement can aggravate the urban heat island (UHI) effect and transfer heat downward, which may cause the problem of permafrost thawing beneath pavements. The objective of this study was to develop a novel cool coating layer (CCL) with high near-infrared reflectance and heat insulation to make the surface of asphalt pavement cool. A self-developed test device and method was established to evaluate cooling effects. Based on the experimental results, the optimal coating can cool asphalt pavement by 11.21 °C when the radiation striking the sample surface is 650 W/m2. This coating, called the composite cool coating layer (CCCL), is composed of the following materials: polyurethane resin, rutile TiO2 of 18%, hollow glass microspheres of 12%, and copper chromite black spinel of 0.7%. Silicon carbide particles of 1 kg/m2 can help the CCCL achieve satisfactory antiskid performance. In conclusion, CCCL can effectively inhibit the absorption of solar radiation and reduce the flow of thermal energy downward without sacrificing skid resistance.

Highlights

Asphalt pavement is widely used in major highways because it has the advantages of offering a smooth and relatively quiet ride and being easy to maintain
In the high-altitude western regions of China, the annual total solar radiation is as high as 7000–9000 MJ/m2, 50% higher than that in eastern regions of China at the same latitude [1]
We investigated a new strategy for a cool coating layer (CCL) with reflective and insulative properties that achieves the needed redirection of solar energy without being unduly expensive and without sacrificing skid resistance

Summary

Introduction

Asphalt pavement is widely used in major highways because it has the advantages of offering a smooth and relatively quiet ride and being easy to maintain. Some researchers have advocated inhibiting the transfer of heat by changing the porosity of the asphalt pavement [18–21], but adopting a largeporosity asphalt mixture can cause serious rutting problems in the summer [22,23] None of these proposed measures do anything to reduce the strong absorption of solar radiation, so they do not prevent the basic problem—heat entering pavements. A small number of scholars have applied cool coatings to cool asphalt pavement [24–30] This method is less expensive and can help reduce the temperature of pavement surfaces effectively. It is of great significance for the protection of frozen soil to improve the cooling effect of cool coatings and inhibit the downward transfer of heat. Disperse lubricants and curing agents were selected as additives to facilitate the formation of coatings

Preparation of Samples

Results and Discussion

Skid Resistance

Findings

Conclusions