For concrete containing nominal maximum size of aggregate of 38 mm. The apparatus consists of a measuring bowl of 0.005 cm capacity. A flanged conical cover assembly fits over the bowl and can be sealed with clamps keeping a rubber gasket in between. A water inlet valve with a spray tube and an air bleed valve are fitted on the conical cover assembly. A pressure gauge is mounted on the top of the stand pipe. A hand pump is provided for the application of pressure