6F2 and 6F5
This is a product produced in the same way as GSB, but is bigger – typically 100mm to 125mm or 4” to 5” in old money, but which can be compacted to form the base for a road.
Confusingly the terms 6F2 and 6F5 refer to a similar product i.e. a 4”-5” Crusher Run but one being produced from quarried material and the other from recycled materials.
Some Quarries refer to 6F2 as quarried stone and 6F5 as recycled, while others use the terms the other way around. Both these products are sometimes known as capping or capping layer and are normally used where a high load bearing capability is required for a road or a building.
Normally this material is laid down in layers and compacted between each layer and then GSB is used for the last 40 – 60mm to trim to the final required level before finishing with either concrete or tarmac.