Porous Asphalt and Permeable Friction Course Overlays

Permeable Pavements Task Committee

Part of: Permeable Pavements


Porous asphalt typically consists of conventional warm mix asphalt (WMA) or hot mix asphalt (HMA) with significantly reduced fines resulting in an open-graded mixture that allows water to pass through an interconnected void space. The porous asphalt surface void space typically ranges from 18% to 25%. In comparison, voids for standard asphalt are typically 2% to 3%, and they are not interconnected. The Franklin Institute in Philadelphia, PA conducted initial development of porous asphalt in the early 1970s. Some of these earlier installations are still functioning well. Significant mix design limitations were addressed in the early 2000s, resulting in durable long-lived pavements appropriate for a variety of uses.

Subject Headings: Pavement overlays | Porous media | Concrete | Voids | Pavement design | Materials processing | Asphalts


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