What is workability of concrete? which test is performed at site for its determination? and what are its recommended values for different purposes?

slump test

workability is basically the flow property of the concrete. in those constructions where the concreting depth is very high like piles, we will require a good workability. 

generally at construction site we do slump test to chek the workibility of the concrete.

in some cases to increase workability we add more water then the extra water is nullified by water reducing admixtures or super plastisizers.