A grade crushed rock is a 20mm minus stone, meaning it is a material composed of every size stone from 20mm down to fine dust. It is the fines that enable crushed rock to compact hard.
This granite stone product is used under paving and concrete slabs, where its main function is to build height and create a stable, compacted base. The A grade offers a more compactable base than B grade.
Standard crushed rock can also be used as an underneath layer for the more decorative crushed rocks to help contain costs.
Apply at a minimum depth of 50mm, moistened with water and compacted with a roller or vibrating plate compacter.