Clean concrete using brushes combined with chemical cleaners or just soap and water. Methods vary depending on how dirty the concrete is and what is soiling it.
In most cases, clean lightly soiled concrete or interior concrete using a pH neutral concrete cleaner. Acidic cleaners remove efflorescence stains and other substances that are dissolved with acid. Alkaline cleansers are helpful for removing grease.
In all cases, use a brush or cleaning machine to scrub the concrete. In the case of severe build up and stains, treat an area twice before rinsing it well. Then, treat surfaces with a concrete sealer appropriate for the application.