Browse through wikipedia and you will find that The concrete slump test is an empirical test that measures workability of fresh concrete.
The test measures consistency of concrete in that specific batch. using eighther concrete testing box or comcrete slamp cone. It is performed to check consistency of freshly made concrete. Consistency refers to the ease with which concrete flows. It is used to indicate degree of wetness.
Consistency affects workability of concrete. That is, wetter mixes are more workable than drier mixes, but concrete of the same consistency may vary in workability. The test is also used to determine consistency between individual batches.
The test is popular due to the simplicity of apparatus used and simple procedure. Unfortunately, the simplicity of the test often allows a wide variability in the manner in which the test is performed. The slump test is used to ensure uniformity for different batches of concrete under field conditions and to ascertain the effects of plasticizers on their introduction In India, this test is conducted as per IS specification. Kafum engineering services is a leader in fabrication of precise designed slump test tools both  cone and squre slump test tools in kenya.