SLUMP TEST OF CONCRETE

Slump Test Of Concrete

Slump test is the most common and simple test adopted to measure the workability of fresh concrete.This test is adopted to check the workability or consistency of freshly mixed concrete in a specific batch.The slump test is used to ensure uniformity for different loads of concrete under field conditions.

Apparatus Used In Slump Test

1. Slump cone with Height of 300 mm, Bottom diameter 200 mm and Top diameter 100 mm.
2. Standard Tamping Rod.
3. Non-Porous Base Plate.
4. Measuring Scale.

Procedure For Slump Test

1. First clean the inner surface of the empty mould and then apply oil to it.
2. Set the mould on a horizontal non-porous and non-absorbent base plate.
3. Fill the mould fully by pouring freshly mixed concrete in the three equal layers.
4. Each layer is tempted 25 times with a standard 16 mm diameter steel rod.
5. When the mould is completely filled with concrete, the top surface is stuck off by means of screening and rolling motion of the temping rod.
6. After filling is completed and the concrete is leveled, the cone is slowly and carefully lifted vertically, an unsupported concrete will now slump.
7. The decrease in the height of the centre of the slumped concrete is called slump.
8. The slump is measured by placing the cone just besides the slump concrete and the temping rod is placed over the cone so that it should also come over the area of slumped concrete.
9. The decrease in height of concrete to that of mold is noted with scale.

Types Of Slump

1. True Slump
2. Shear Slump
3. Collapse Slump

1. True Slump

In true slump concrete just subside shortly and more or less maintain the mould shape.This type of slump is most desirable.

2. Shear Slump

If one-half of the cone slides down in an inclined plane, it is called a shear slump.It indicates lack of cohesion in the concrete mix.

3. Collapse Slump

When the sample is collapse due to adding excessive water, it is known as collapse slump.