Thermal profiles in pervious concrete during summer rain simulations

Résumé

Pervious concrete pavement systems may have many environmental benefits including the mitigation of heat
island impacts. This mitigation is a complex combination of pervious concrete‟s insulating capability and its
ability to store water which may provide evaporative cooling. However, the introduction of water may also
bring heat into the system, where the system is the pervious concrete pavement layer over an underground
aggregate bed for retention and/or detention of stormwater. This study involved three different mix design
placements in southern Brazil on a hot sunny summer day. The experiment had a control section and two test
spots where controlled artificial rain events were introduced at two times during the afternoon for each of the
three placement types. The „rain‟ initially brought heat from the surface into the pervious concrete layer.
Subsequent evaporation cooled these interior pavement layers to levels similar to the control locations. This
introduction of water into pervious concrete with very hot surface temperatures in the heat of the day is
expected to be a severe condition for adding heat to the system through the flow of water. If water additions
are made at different diurnal times, such as nighttime rain, they may provide similar evaporative benefits
with less heat transfer into the system via the water phase, and thus even more cooling of the system. These
experiments reinforce the conclusion that pervious concrete may be a cool pavement during summer
conditions, even under extreme conditions when surface heated stormwater enters the system.
Keywords: pervious concrete pavement, stormwater, heat island