Using a dry soft brush mop, sweep all dirt and dust off the floors into a dustpan. Then dilute water with a cleaning agent in a bucket. You will also need a rather big cotton rag or a special napkin, a rag for mopping. After wetting the rag in a soapy solution, wash the floors as you like, manually or by using a mop. Do not forget to wipe the concrete dry with a dry rag. You can also choose the best steam cleaner for tile and grout if you want to do the cleaning quicker.