Thermal Behaviour of Innovative Acoustic Pavements for the Life Cool & Low Noise Asphalt Project

By the end of the 21^st Century heat waves are expected to increase in frequency, duration and intensity due to climate change. Therefore, cities must find solutions to limit heat-related health impacts on their population. Many ways to mitigate the effects of heat waves exist, such as urban greening or cool pavements.

Since 2013, the City of Paris has been experimenting pavement-watering using its non-potable water network. The results of these experiments have shown that this cooling strategy allows a reduction of up to 2 to 3°C UTCI-equivalent temperature.

Since 2017, the Cool & Low Noise Asphalt project, co-funded by the European Union's Life program, aims to study the thermal performance of three innovative pavements compared to traditional asphalt concrete, as well as their acoustic performance. These pavements have been developed to optimize the effects of pavement-watering thanks to their surface texture and porosity that is expected to offer greater water retention and longer pavement-watering cooling effects.

Three experimental sites are divided into three portions: innovative portion (innovative pavement) and traditional portion (repaved with standard asphalt), which are both watered, and a control portion (original pavement) that isn’t watered. Each of the portions are equipped with a weather station to monitor a multitude of meteorological parameters to evaluate the effectiveness of the innovative pavement and pavement-watering.

Based on the temperature and heat flux measurements conducted 5 cm deep in the pavement, the thermal analysis shows a positive impact of watering. From the analysis of the heat flux hysteresis, the surface cooling flux and evaporation rate are estimated. The differences in observations are discussed in light of street orientation and pavement materials.