Explanation of the problem

Asphalt can reach temperatures of 60°C or even higher during hot days. Heat softens asphalt and makes it sticky by melting the binder (bitumen) in the surface layer. This leads to rutting or even damages to the road surface. At intersections, traffic lights, and curves, asphalt sticks to car tires, causing potholes in the road surface. Asphalt also retains heat for an extended period; cooling occurs slowly, so during hot periods, the asphalt doesn’t have sufficient time to cool down at night. Concrete pavers and pavement slabs are also affected by heat; they expand, rise, and may break.

Damage to pavement is particularly problematic for road authorities and the transportation sector. At critical infrastructure nodes such as ports, pavement damage can lead to cascade effects.

Information and maps for better understanding

Basic maps according to the standardized stress test

  • Map showing the number of warm nights per year (Climate Impact Atlas) → provides an indication of the increase in the number of nights when asphalt cannot cool adequately at night.
  • Detailed heat map of the perceived temperature on a hot day Climate Impact Atlas) → provides insight into the locations where pavement is at risk of overheating.

Additional maps

  • Map showing the number of summer or tropical days now and in the future (Climate Impact Atlas) → provides insight into the number of days when pavement damage may occur.
  • Locations of asphalt roads and concrete pavement.

Some measures and guidelines

  • Modify the asphalt mixture by incorporating harder bitumen or polymers.
  • Add white stones to asphalt or concrete paving stones to reflect more radiation and reduce temperature.
  • Install asphalt with an open structure, allowing (rain)water to flow through and provide cooling.
  • Create shade on the road surface.
  • As an emergency measure, spread salt: salt attracts moisture from the air, cooling the asphalt. Additionally, salt extracts moisture from the asphalt, making it less fluid.