To study the workability (determine the consistency) of prepared concrete either in the laboratory or laboratory or during the progress of work in the field and to check the uniformity of concrete from batch to batch.
Mould for slump test, non porous base plate, measuring scale, temping rod. The mould for the test is in the form of the frustum of a cone having height 30 cm, bottom diameter 20 cm and top diameter 10 cm. The tamping rod is of steel 16 mm diameter and 60cm long and rounded at one end.
A concrete mix (M15 or other) by weight with suitable water/ cement ratio is prepaid in the laboratory similar to that explained in 5.9 and required for casting 6 cubes after conducting Slump test.
i. Clean the internal surface of the mould and apply oil.
ii. Place the mould on a smooth horizontal non- porous base plate.
iii. Fill the mould wit5h the prepared concrete mix in 4 approximately equal layers.
iv. Tamp each layer with 25 strokes of the rounded end of the tamping rod in a uniform manner over the cross section of the mould. For the subsequent layers, the tamping should penetrate into the underlying layer.
v. Remove the excess concrete and level the surface with a trowel.
vi. Clean away the mortar or water leaked out between the mould and the base plate.
vii. Raise the mould from the concrete immediately and slowly in vertical direction.
viii. Measure the slump as the difference between the height of the mould and that of height point of the specimen being tested.
The above operation should be carried out at a place free from Vibrations or shock and within a period of 2 minutes after sampling.
The slump (Vertical settlement) measured shall be recorded in terms of millimeters of subsidence of the specimen during the test.
Slump for the given sample=