Influence of Heat Reflective Coating on the Cooling and Pavement Performance of Large Void Asphalt Pavement

Abstract

To reduce the temperature of asphalt pavement in summer, and alleviate the urban heat island effect, a comprehensive method of combining a heat reflective coating and large void asphalt pavement was proposed. Using the developed coating cooling test equipment, the cooling effect of the coating on a large void asphalt mixture was studied in six different proportions, four different colors, and four different dosages, and the durability of the coating was verified by abrasion tests. Finally, the best dosage of the coating was recommended through an adhesion test of the coating, and a water permeability and anti-skid performance test of the pavement. The results show that the reflectivity of the coating can be improved by adding functional fillers, of titanium dioxide and floating beads, into the coating. The order by reflectivity and cooling effect of the four color coatings was green > red > gray > blue, and the maximum cooling value of the green coating reached 9.7 ℃. The cooling performance of the coating decreased with the increase of wear time, and the rate of decrease was fast, then slow, and finally tended to be stable after 20,000 times wear. The coating reduced the anti-skid performance and the water permeability coefficient of large void asphalt pavement, but still maintained a high level. The green coating with 15% titanium dioxide and 10% floating beads is recommended as the cooling coating for large void asphalt pavement, and its dosage should be controlled at about 0.4–0.8 kg/m2.

Urban Heat Island Mitigation through Planned Simulation

“…On the other hand, Qin et al [62] concluded that to achieve optimal results for mitigating UHI effects, the areas where road materials are replaced with those that have higher albedo indexes must have a proportionality less than or equal to 1.5 between the height of buildings and the width of roads; when these measures are considered, solar radiation reflected by roads is not absorbed by the surfaces of buildings, thus avoiding the thermal discomfort of its inhabitants. Another strategy to improve asphalt reflectance is to add titanium dioxide-based dyes to the asphalt mixture, which can achieve similar results to those of concrete pavements according to Zheng et al [63]. In addition, there are other mitigation alternatives such as those proposed by Cortes et al [64]; in their UHI simulation analysis, carried out in Mandaue City on Cebu Island, adding green roofs and vegetation helped decrease air temperature and LST by 0.4 and 1.1 • C, respectively.…”

Evidence-based Guidance on Reflective Pavement for Urban Heat Mitigation: A Case Study in Phoenix, Arizona

“…For comparison, an untreated AC surface had a consistent reflectivity of 12%, reflecting half as much solar radiation as the aged RP surface, and a third as much as the new RP surface. Reduction in reflectivity for RP is likely due to wear, dust accumulation, rubber residual, and other materials 54 .…”

Study on the Photothermal Performance of a “Thermal Shielding” Coating Using Tungsten Bronze as Functional Material for Asphalt Pavement

“…Surface gritting with light-colored aggregate, chip seals with light-colored aggregate, sealing, resurfacing, coatings and pigments, and other methods can increase the reflectivity of pavement surface [9,11]. In recent years, with the rapid development and wide application of organic resin materials and nanomaterials, pavement reflective coating has been the most preferred technique for reflective pavement, with merits such as excellent and controllable optical properties, simple construction, strong adhesion to asphalt pavement, and no adverse effects on the mechanical properties of asphalt mixtures being proven [12][13][14].…”