Study Finds That Permeable Concrete Can 'Cool Off' Urban Areas

A specimen of permeable concrete collected by Rutgers University researchers. Photo courtesy of Hao Wang/Rutgers University.

A team comprised mostly of researchers from Rutgers University (New Brunswick, New Jersey, USA) published a study which found that special permeable concrete pavement can help reduce the “urban heat island effect,” a phenomenon that makes cities significantly warner due to human activity.  

According to the study, impermeable pavement made of concrete or asphalt makes up over 30% of most urban areas. During the summer months, impermeable pavement can reach temperatures of 60 °C (140 °F). In cities with a minimum population of 1 million people, the average temperature increases by an average between 1.8 to 5.4 degrees over less densely populated areas. The increased heat in these urban areas can pose health risks to humans, as well as to aquatic life in the form of surface runoff, and cause a higher demand for air conditioning that leads to environmental and economic costs. 

With those concerns in mind, the Rutgers team designed permeable concrete pavement with large connected pores that allows water to drain through and evaporate, thereby reducing the temperature of both the pavement and its surface. While this form of concrete gives off slightly more heat on sunny days than conventional concrete, it also gives off 25-30% less heat on days following a rainfall and has a high thermal conductivity that enables it to transfer heat more quickly to the ground.

“Highly efficient permeable concrete pavement can be a valuable, cost-effective solution in cities to mitigate the urban heat island effect, while benefitting stormwater management and improving water quality,” says corresponding author Hao Wang, an associate professor in the Department of Civil and Environmental Engineering in the School of Engineering at Rutgers University–New Brunswick.

One limitation associated with permeable pavement is that its lack of durability relative to impermeable concrete, which is why it’s mainly used for sidewalks, parking lots, rest areas, and other areas with light pedestrian traffic. For this reason, the Rutgers-led team is currently investigating ways to make permeable concrete stronger and more durable so that it can be used in city streets.

The authors of the study published in the Journal of Cleaner Production include current and former professors, researchers, and doctoral students from Rutgers, along with collaborators at the New Jersey Department of Transportation and Central South University in China.

Source: Rutgers Today,