01658401

Component

Pavements contribute significantly to the development of Urban Heat Islands (UHIs). This is impacted by the local climate and urban form, as well as the thermal and optical properties of the pavement, which are usually not measured. Field cores of asphalt concrete (AC) pavements from five locations in Illinois were used to evaluate the optical and thermal properties of existing pavements. Thermal conductivity ranged from 1.0 to 3.0 W/mK, diffusivity 0.6 to 2.0 mm²/s, and heat capacity 0.7 to 3.0 MJ/m³K, which differ significantly from values typically used in pavement design. The same cores were used to extend a simplified bilinear aging albedo model, with the asymptotic albedo and at-construction albedo being largely within the expected range of 0.10 to 0.20 and 0.05 to 0.10, respectively. These properties as well as historical weather data from each of the locations were used to evaluate the local pavement Radiative Forcing (RFp) and Global Warming Potential (GWP). The highest RFp of about 65 W/m² was observed in a location in Southern Illinois, which receives more sunlight annually than the other locations. GWP was found to increase with service life. An Average Day (AD) metric was also applied on net surface heat flux and surface temperature to highlight differences because of thermal properties, which GWP does not properly capture. Surface temperatures were found to vary, with lower values of conductivity and heat capacity leading to higher surface temperatures and hence an increased UHI.

This paper was sponsored by TRB committee AFD00 Section - Pavements.

18-01278

English

0000-0001-6194-269X

4p

2018

Transportation Research Board 97th Annual Meeting

Digital/other

References

Asphalt concrete pavements; Core samples; Global warming; Heat islands; Optical properties; Surface temperature; Thermal properties

Radiative forcing

Illinois

Environment; Highways; Pavements

Transportation Research Board Annual Meeting 2018 Paper #18-01278

TRIS, TRB, ATRI

Jan 8 2018 10:19AM