- Porous asphalt is permeable to water

- Porous asphalt is similar to permeable/pervious concrete (function)

- Composed of larger stones in comparison to regular asphalt; different asphalt binders

- Material allows water to pass/drain through the asphalt layer

- Underlying open-graded stone bed - After a storm water event: rainwater drains through the concrete layer into underlying stone bed

- Infiltration through stone bed into soil/groundwater

- Porous asphalt is a hard surface ( roadways/areas with higher traffic)

-Application areas: parking lots, streets, driveways…

Basic information

Type: 
Retrofitting + Creation
Challenge: 

Performance

Evapotranspiration none none
Shading none none
Reflection (Albedo) none
Water Conveyance none
Water Infiltration 1
Water Retention none
Water Storage none
Water Reuse none
Water Filtering none
Water Bio-remediation none
Deposition none
Bio-filtration none
Habitat Provision none
Connectivity none
Beauty / Appearance none
Usability / Functionality 1
Social Interaction none
Role of Nature / Mode of Action: 
- Permeable concrete  water regulation function - Porous medium  the soil - Reduced flood risk compared to typical roads, where water runs off the surface
Technical & Design Parameters: 
- Quite simple technology - Porous asphalt consists of larger stones compared to regular asphalt - Use of different asphalt binders - Use of standard equipment that is used to build e.g. roads for regular asphalt - Careful planning of the underlying bed size/depth to avoid that the water level rises into asphalt layer (stone bed depth: 18-36 inches)
Conditions for Implementation: 
- Greater effort ( roads have to be repaid)
Benefits & Limitations: 
Benefits: - Water regulation with space which is used for traffic (no more space is needed) - Can be used to slow traffic and reduce noise - Reduces storm runoff by 70-90 % - Improves water quality (removes 85-95% suspended solids, 65-85% phosphorus, 80-85% nitrogen 30% nitrate, up to 98% metals)

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No. 730052 Topic: SCC-2-2016-2017: Smart Cities and Communities Nature based solutions