Permeable pavements: Specifications

Specifications for pervious concrete, porous asphalt, and permeable pavers

Material	Specification	Quantity
Pervious concrete	NO4-RG-S7 mix with air entrainment proven to have the best freeze-thaw durability after 300 freeze-thaw cycles. 28 day compressive strength = 5.5 to 20 MPa. Porosity between 14% to 31%. Permeability = 900 to 21,500 mm/hr. Proprietary pre-cast slabs meeting required specifications are also available.	Thickness will range from 100 mm - 150 mm depending on the expected loads.
Porous asphalt	Open-graded asphalt mix with a minimum porosity of 16%. Polymers can be added to provide additional strength to heavy loads. The University of New Hampshire Stormwater Center has detailed design specifications for porous asphalt.	Thickness will range from 50 mm - 100 mm depending on the expected loads.
Permeable Interlocking Pavements	Pavers shall meet the minimum material and standard specifications for precast concrete pavers (CSA A231.2 in Canada; ASTM C936 in United States). Open space between pavers (i.e. joint space) typically ranges between 5 and 15% of the total surface area. ASTM No. 8 (5 mm dia.) crushed aggregate is recommended for fill material in the paver joints (typically HPB). For narrow joint pavers, a smaller sized aggregate may be used. Narrow joints are required where pavement must be AODA compliant.	For vehicle applications the minimum paver thickness is 80 mm For pedestrian applications the minimum paver thickness is 60 mm and joint widths should be no greater than 15 mm.

A mixture of mineral aggregates bound with bituminous materials, used in the construction and maintenance of paved surfaces.

The porosity (n) of a mixture is the ratio of the volume of void-space to the total or bulk volume of the mixture. It is closely related to the concept of void ratio (e) where void ratio is the ratio of the volume of void-space to the volume of solids. n = Volume of voids/Total volume of mixture = e/(1+e)

The porosity (n) of a mixture is the ratio of the volume of void-space to the total or bulk volume of the mixture. It is closely related to the concept of void ratio (e) where void ratio is the ratio of the volume of void-space to the volume of solids. n = Volume of voids/Total volume of mixture = e/(1+e)

A broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations.