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New porous pavements should be inspected several times in the first few months after construction and at least annually thereafter. Inspections should be conducted after major storms to check for surface ponding that might indicate possible clogging.


It is recommended that vacuum sweeping be performed at least twice a year. In environments where larger amounts of fine materials are present, the frequency should be increased accordingly. The Virginia Transportation Research Council recently published a study that evaluates how porous asphalt performs when it’s maintained using various vacuum sweeping protocols.


It is very important that sand and abrasives not be used for winter maintenance, as they will clog the pores; de-icing materials should be used instead. The University of New Hampshire’s research suggests that porous asphalt retards the formation of ice on the pavement surface, so that the use of de-icing compounds may be drastically curtailed.


In Europe and Japan, large pressure washing/vacuum equipment has been used to restore permeability on porous surfaces on roadways (referred to as open-graded friction courses in the US) that have become clogged. Little research has been done on restoring permeability to porous pavement structures.


If the porous pavement is damaged, it can be repaired using conventional, non-porous patching mixes, as long as the cumulative area repaired does not exceed 10 percent of the paved area.


Maintenance Bonus: 75 percent reduction in de-icing chemical use

The two photos below show a parking lot at University of New Hampshire one hour after plowing, with a close-up of the porous asphalt portion of the lot at bottom. Porous and non-porous areas were evaluated for the degree of snow and ice cover and the friction factor. A 75 to 100 percent reduction in salt application was possible. That is, with only 0 to 25 percent of the salt, the snow and ice cover on the porous asphalt was the same as on conventional dense-mix asphalt. This reduction can be achieved without compromising braking distance or increasing the chance of pedestrians slipping and falling. In a number of cases, it has been reported that no deicing chemicals are needed, and plowing alone is sufficient to remove snow from the paving surface.

Winterconventional.jpg       Winterporouslot.jpg
Conventional asphalt one hour after plowing       Porous asphalt one hour after plowing