This property of consistency or stiffness is called the slump. Slump Slump is a convenient way to approximate the water to cement ratio in the field. Slump is measured with a slump cone. The cone is removed and placed next to the pile of concrete. The difference between the top of the slump cone and the top of freshly molded concrete is the slump.
More flowable concrete is said to have a higher slump.
The desirable characteristic of a high slump is that it is easier to work with when it is placed. The undesirable side is that it will create an inferior product unless the concrete is allowed to cure for a longer time. The reason that the concrete will be inferior, if not allowed to cure for the proper amount of time, is because the concrete will develop an unwanted amount of capillaries. Again, this translates into a less waterproof, less water vaporproof and weaker concrete. Water is an essential chemical ingredient in the making of concrete, however we need to use more of it than is chemically necessary in order to place the concrete with some degree of ease.