01551927

Component

Temperature of pavements substantially influence on the distresses and service life of flexible pavements because of the temperature dependent viscoelastic nature of asphalt concrete. In addition, pavement surface temperature is directly related to the roadway safety and environmental issues such as formation of ice during winter and urban heat island effect during summer. This study investigates the feasibility of mitigating temperature-related issues on asphalt pavement by controlling thermal properties of asphalt concrete. High density expanded polypropylene beads and graphite powder were tested to change the thermal properties of asphalt concrete, and their effects on the mechanical properties were investigated experimentally. Test results show that the asphalt concrete containing 18% by volume of the expanded polypropylene has the decreased thermal conductivity, heat capacity, and indirect tensile strength by 17%, 32%, and 27%, respectively. On the other hand, adding proper amounts of graphite powder improves indirect tensile strength up to 40% and increases thermal conductivity up to 43%. A series of heat transfer analysis was conducted using a finite difference heat transfer model to investigate the effect of the thermally modified asphalt mixtures on the pavement surface temperature. Results show that the amplitude of daily temperature variation reduces as the thermal conductivity increases. This implies that the graphite modified asphalt concrete is effective in thermal regulation of pavement surface, and can provide a green and cost effective solution for mitigating urban heat island effect and reducing the use of deicing agents. The simulation using the thermal properties of the asphalt concrete with 4.8% graphite shows that the maximum surface temperature drops 1.9ºC in summer, and the minimum surface temperature increases 0.3ºC in winter.

This paper was sponsored by TRB committee AF000 Design and Construction Group.

01550057

15-3651

English

0000-0001-9404-9128

20p

2015

Transportation Research Board 94th Annual Meeting

Digital/other

Figures; Photos; References; Tables

Asphalt concrete pavements; Graphite; Mechanical properties; Polypropylene; Surface temperature; Thermal properties

Highways; Maintenance and Preservation; Materials; Pavements; I31: Bituminous Binders and Materials; I32: Concrete; I60: Maintenance

Transportation Research Board Annual Meeting 2015 Paper #15-3651

TRIS, TRB, ATRI

Dec 30 2014 1:13PM