There are two primary steps to pouring exposed aggregate concrete, according to the Concrete Network. The base concrete is mixed and then poured into slab form using a shovel or concrete mixer, where it is struck off and bull floated. The decorative aggregate is then spread over the slab by hand or shovel until it covers the top of the slab and the embedded top using the bull float.
According to the Concrete Network, an alternative to the two-step method is to mix the decorative aggregate directly into the concrete base and pour both elements into slab form. A less expensive alternative involves mixing the aggregate with concrete and spreading a thin layer of the mixture over an already-poured slab. The thin layer should be between 1 inch and 2 inches thick.
In all instances, once the aggregate is poured, it must be exposed as a final step. The aggregate can be exposed by washing the thin film of concrete off the stones with water and then brushing the slough away with a broom. The time allowed between laying the aggregate and exposure can be extended up to a day by spraying the surface with a chemical retardant that prevents the thin film of concrete on the aggregate from drying.