The role of road pavements in the phenomenon of Urban Heat Island

The thesis aims at proposing a comprehensive study concerning the role of road pavements with respect to the phenomenon of the urban heat island that are generated within the anthropized areas, i.e. all the dynamics that determine a sensible increase of the urban temperatures with respect to that recorded in the surrounding rural environments. More specifically, the core of the research concerns an extensive experimental activity aimed at evaluating different construction solutions to obtain thermal-optimized road pavements. Such solutions consist of clear or colored road pavements made with non-black surfaces and are manufactured with different techniques. Therefore, the main purpose of the whole research regards the definition of advices, indications and guidelines for the production of road pavements able to mitigate the urban heat island and prevent an excessive increase of the urban temperatures. Laboratory and outside activities were scheduled to identify the chromatic characteristics and monitor the thermal properties and responses of the selected technologies. Using a multi-scale approach (from binders to mixtures), an advanced mechanical characterization of the materials was also proposed to assess their suitability since each alternative must ensure adequate standards from functional, safety and durability points of view. A back calculation based on all the collected data permitted the evaluation of the efficacy of the proposed technologies in mitigating the urban heat. Finally, further aspects involved in the use of thermal-optimized pavements, but not directly related to thermal concerns, were also studied: mainly, such aspect regarded the infrastructure-landscape integration of clear or colored surfaces, their possible use as traffic calming measures (and the related road safety matter), their repercussions on the nightly artificial illumination or that needed within the road tunnels. Furthermore, some efforts were also spent in order to investigate their impacts with respect to the human comfort (thermal and visual ones) and the human health. Principal findings of the research stated that some technologies (clear mixtures containing synthetic transparent resins and valuable clear aggregates) were effectively able to contain the temperatures reached during the direct solar exposition (more intense in the summer). The most effective material was useful to lower the maximum reached temperature of about 18 °C with respect to that of a traditional black mixture conventionally employed as wearing courses in urban roads (assumed as reference).