There are many construction projects that require the use of stone or its derivatives. Whether you are a construction company buying stone by the truckload or a homeowner laying a new patio, you need to understand the difference between some of the more common types of manufactured stone, crushed, quarry process and stone dust, and which of them best meet your needs.
As the name implies, crushed stone is simply stone that has been reduced in size and screened to ensure uniformity of size.
Usually it is made of granite-gneiss, trap rock, limestone or any combination of these materials. It is sold in different sizes, each suitable for different uses.
- 3/4 inch crushed stone – usually used as an aggregate in cement or asphalt, commonly used in the construction of roads
- 1 1/2 inch crushed stone – used for gravel driveways, septic fill, ballast for railroads and to enhance drainage
- 2 1/2 inch crushed stone – mainly used to prevent erosion on roadsides and in drainage ditches, also often laid at the entrance to long-term construction projects.
Quarry process, also known as QP, dense grade aggregate (DGA), crusher run and road stone, is a combination of small, 3/4-inch-or-less crushed stone and stone dust. Most often it is made out of crushed limestone, granite-gneiss, trap rock or a combination of the aforementioned. It is designed to bind together and form a strong, solid surface when compacted.
Quarry process can be used anywhere strength and durability is required. It is often found in driveways, as both a road base and road surface, walkways, bike paths and it can be used as clean fill. For patios and walkways it is often used as part of the sub base to provide strength and stability.
Stone dust, also known as stone screenings, is the finest of the types of crushed stone. It is made of the same type of stone as the other types but is crushed into a powder. When used by itself stone dust forms a hard surface that is water resistant. When used with a larger stone it acts as a binding agent.
Because of its ability to form a strong, non-porous surface, stone dust is often used in between the stones or bricks in patios and walkways. In this application, it not only protects the base of the area from moisture, thus preventing heaving or mold growth, but it also effectively keeps weeds and grass from growing up between the pavers. It serves the same purpose when used in horse arenas, biking and hiking trails and walkways.
Stone dust is also used as a binding agent in cement or asphalt for roads, driveways and sidewalks.
All three of these types of manufactured stones serve a distinct purpose. Be sure you have a clear idea of exactly which of these you will need to successfully complete your project before making a trip to the local quarry. Frequently the plans may call for more than one of these types of crushed stone, particularly if the construction involves excavating and then rebuilding the area with various layers to provide stability and durability.
If you are unsure about the amount of these crushed stones you will need or which would best suit your needs, talk to your local quarry. Nobody knows stone and its uses better than they do.