The concrete mass after the test when slumps evenly all around without disintegration is called the true slump.
When one-half of the concrete mass slide down the other is called the shear slump. This type of slump is obtained in a lean concrete mix.
When the sample is collapsed due to adding excessive water, it is known as collapse slump.
For very stiff or dry mixes it does not show any changes of the slump after removing the slump cone.