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===Foundation aggregates===
 
===Foundation aggregates===
 
[[File:Geogitter-4.jpg|thumb|Geogrids like these are sometimes incorporated into the layers of permeable pavement foundation aggregates to provide additional stability and conserve aggregate material]]
 
[[File:Geogitter-4.jpg|thumb|Geogrids like these are sometimes incorporated into the layers of permeable pavement foundation aggregates to provide additional stability and conserve aggregate material]]
Most [[OPSS aggregates]] are not recommended for use in permeable paving systems. The exception being type 'o' with a default void ratio of 0.3.  
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All aggregates should meet the following criteria:
*[[Choker layer]]
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* Porosity of 0.4
*[[Reservoir aggregate]]
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* Maximum wash loss of 0.5%
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* Minimum durability index of 35
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* Maximum abrasion of 10% for 100 revolutions and maximum 50% for 500 revolutions
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Most [[OPSS aggregates]] are not recommended for use in permeable pavements, with the exception of 'Granular O' type.
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'''<u>Granular Subbase</u>'''
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Should be clear, crushed 50 mm diameter stone, graded in accordance with ASTM D2940.
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<u>'Rain ballast' aggregate (63 mm) would also be suitable</u>
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'''<u>Granular Base</u>'''
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Should be clear, crushed 20 mm diameter stone conforming to ASTM C33 No 57
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'''<u>Bedding</u>'''
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Should be clear, crushed 5 mm diameter stone, graded in accordance with ASTM C33 No 8, High Performance Bedding (1-9 mm diameter), or equivalent. Typical bedding thickness is between 40 mm and 75 mm.  
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For more information, also see [[Aggregates]] page.
    
===Geotextile===
 
===Geotextile===
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