Concreters mix, lay, spread, compact and finish concrete for building and construction work. They mix cement with other materials such as gravel, sand and water, and pour the concrete, usually over steel reinforcement, moving it into position using a pump. They also prepare and move boxing, or formwork, so that it contains the concrete in the right shape and dimensions. Once the concrete has been poured, concreters level the concrete, clean and seal it. They might also create decorative surfaces on the concrete prior to cleaning and sealing. They may also spray concrete onto retaining walls, swimming pools or other surfaces that require rendering.