Winter Road Science: How Permeable Pavements Freeze

Winter's freeze-thaw cycle poses significant challenges for road infrastructure. A seven-winter study in Madison, Wisconsin, examined the underground temperature behavior of three permeable pavement types: interlocking concrete pavers, pervious concrete, and porous asphalt. Researchers found that interlocking pavers experienced fewer days below freezing and maintained warmer subsurface temperatures compared to the other two materials. This difference is crucial as unfrozen ground can continue to absorb meltwater, preventing surface pooling and refreezing.

The experiment involved detailed temperature monitoring of the pavement and aggregate base layers. Over 303 winter days, the subsurface layers beneath pavers remained above freezing more consistently than those under pervious concrete or porous asphalt. For instance, the bottom layer beneath pavers stayed unfrozen on 81% of days, compared to 74% for the other two types. Extended cold periods also showed pavers freezing less completely than pervious concrete and porous asphalt.

These temperature variations have implications for road maintenance and environmental impact. When subsurface layers remain unfrozen, meltwater can infiltrate effectively, potentially reducing the reliance on road salt. Studies suggest permeable pavements could significantly decrease salt usage. However, researchers emphasize that dissolved chlorides can still reach groundwater. Thus, minimizing salt application remains advisable, even with permeable surfaces.