According to the January 24, 2022 Memorandum from the Illinois DOT, aggregates are divided into two common uses: Lift and Cap. CS1 or RR1, two terms for this class of course aggregate may be used as bedding fill for the improvement of subgrades with finished, compacted lift thicknesses of between 12 to 24 inches. This recycled material is then capped with CA6 and the entire roadbed will provide both good stability and drainage.
For additional information on this, see our page Why Recycled Aggregate?
According to the January 24, 2022 Memorandum from the Illinois DOT, aggregates are divided into two common uses: Lift and Cap. CA6 is used for placing a three inch compacted cap over the 12-24" subgrade improvement using RR1 3" materials. CA6, commonly known as road gravel is used as a compactable base material and is 3/4" stone (or recycled concrete, brick, etc) or less. At a thickness of 2", one ton of this material will generally cover 100 square feet of area.