The workability of concrete is another quality to consider. The concrete should be placed with the stiffest consistency possible, but still be reasonable to finish. A measure of concrete workability is slump. I shows suggested slump ranges for various types of construction. High slump, or flowing concrete usually contains excess water which dilutes the water-cement paste which makes it weaker.
Enough water is needed for full curing, but excess water leaves voids when it evaporates.
Concrete made with excess water also experiences greater shrinkage, which typically adds to more cracking. If high slump concrete is essential to the success of the project, you can produce it by using one of the high range water reducer admixtures, also called super-plasticizer. These admixtures greatly increases the workability of the concrete for as much as 30 minutes, after which the concrete returns to its original form. Recommended maximum slump. Hand consolidating includes rodding and spading.