Pavement albedo and sustainability: an experimental investigation

Albedo, or solar reflectance, is the ratio of reflected solar radiation to the total amount that falls on that surface, known as incident solar radiation. Albedo values range from 0, for perfect absorbers, to 1, for perfect reflectors. Surface albedo is linked to many effects and issues. From an environmental standpoint, the following related issues can be listed: urban heat island effect, air-conditioning energy and smog reductions, sunlight’s heating of the air near the surface, insufficient reflection, raising of the temperature of the pavement and thus of the temperature of the air that is near it, heating of the city, turning on of the air conditioners, further heating of the outside air and increasing costs energy, use of the thermal energy to drive the conversion of organic gases and nitrous oxides into smog. From a mechanistic standpoint, stiffness of asphalt, viscosity, lifecycle costs of maintenance and disposal of pavements, rutting performance, durability are affected by the thermal characteristics of the pavement. Finally, illumination, aesthetics of street pavements in cities and visibility refer to other non-negligible effects. In the light of the abovementioned facts, the objectives and scopes of the paper addressed the analysis of sustainability and albedo characteristics for several types of surface courses. Experiments on different pavements were carried out and a methodology was set out. For the pavements under investigation, the differences between dense-graded and open-graded friction courses did not result always substantial. Furthermore, analyses and tests demonstrated that the analysis of the consequences on albedo of the addition of recycling powders calls for further research.