The Vebe test is conducted on concrete to identify its workability, preferably for dry mixes.
The test apparatus comprises a cylindrical chamber measuring nine and a half inches in diameter and eight inches in height, a slump cone, and a transparent disc-shaped rider. This entire setup is positioned on a vibrating table.
A standard slump cone placed in the cylinder is filled with concrete in a standard way, and the slump cone is removed, leaving the fresh concrete in the shape of a truncated cone.
Then, a 6-pound transparent disc-shaped rider supported by the apparatus is placed on top of the concrete cone.
Operating at 50 cycles per second, the vibrating table induces a vertical movement to facilitate concrete compaction in the cylinder.
Concrete in the cylinder is considered thoroughly compacted when the transparent rider is entirely obscured, indicating no visible voids on the concrete surface.
The workability of the mixture, indicated by the energy needed for full concrete compaction, is measured in Vebe seconds, which is the duration of the concrete transition from a slump cone shape to a cylinder.
