Materials for transit-mixed (also known as truck-mixed) concrete are batched at a central facility and entirely mixed in the truck while in route. Transit-mixing separates the water from the cement and aggregates, allowing the concrete to be mixed shortly before placement on the job site. The water added during transit mixing must be clean tap water without any additives or admixtures. It is important that the water used to mix the concrete is free of sediments and other impurities that could affect its ability to set properly. Concrete placed in this manner will not have the same long-term durability as place-mixed concrete, but it does provide immediate strength and workability. The concrete's shorter setting time also allows workers more time to complete other tasks while still providing sufficient time for the concrete to reach its full strength. Transit-mixed concrete is used where quick placement and maximum output are essential. This type of concrete can be used for driveways, parking lots, and sidewalks. It can also be used for small structures such as flatwork and steps since it can be placed almost immediately after it is mixed. Place-mixed concrete is mixed by hand or with mechanical equipment on site prior to use. This gives the mixer operator more time to adjust the mixture for different types of applications and to incorporate additional materials into the mix. For example, dry sand can be added to increase the density of the concrete if necessary.