Gravel

All aggregates should meet the following criteria:

• Maximum wash loss of 0.5%,
• Minimum durability index of 35,
• Maximum abrasion of 10% for 100 revolutions and maximum of 50% for 500 revolutions.

• Granular material for underdrains should be clear crushed 50 mm diameter stone graded in accordance with ASTM D 2940.
• The void space ratio should be 0.4 (or 40%)
• A 100 mm layer of smaller grade pea gravel should be laid over the clear stone to reduce the chance of puncture damage to geotextile fabric.

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.

Gravel, or crushed stone of various size gradations (i.e., diameter), used in construction; void forming material used as bedding and runoff storage reservoirs and underdrains in stormwater infiltration practices.

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

Filter fabric that is installed to separate dissimilar soils and provide runoff filtration and contaminant removal benefits while maintaining a suitable rate of flow; may be used to prevent fine-textured soil from entering a coarse granular bed, or to prevent coarse granular from being compressed into underlying finer-textured soils.