Aggregates are coarse granular materials which are used for construction purposes. They have good binding and draining properties, so will often be used to form solid foundations for building on. There are a number of different types, all of which have their own purposes and can prove useful in various different settings.
Sand is a particularly common aggregate in construction. It comes in different consistencies – soft sand is used in bricklaying, pointing, wall construction, paving and plastering. Sharp sand, or concrete sand, is usually used to make concrete. It has larger particles and is more coarse.
Gravel and crushed rock are also popular aggregates, and are often used for decorative purposes in landscaping. They might also be used as a sub base under asphalt or for roads and driveways.
Some aggregates will be made up of recycled materials. The most common kind is blast furnace or steel furnace slag. These are a by-product left over by other industrial processes, and can be used to make different kinds of cement.
This is a brief overview of some common kinds of aggregate. There are many others available, and all will be useful in different circumstances depending on the situation.