Test for workability of concrete - slump test

The concrete Slump Test is a measurement of concrete's workability or fluidity. It's an indirect measurement of concrete consistency or stiffness.

A slump test is a method used to determine the consistency of concrete. The consistency, or stiffness, indicates how much water has been used in the mix.

The stiffness of the concrete mix should be matched to the requirements for the finished product quality.

Slump Test Apparatus
-Slump cone,
-Scale for measurement,
-Temping rod (steel)

Types Of Concrete Slump
The slumped concrete takes various shapes, and according to the profile of slumped concrete, the slump is termed as;

1-Collapse Slump
2-Shear Slump
3-True Slump

The procedure of the Concrete Slump test:
1-The mold for the concrete slump test is a frustum of a cone, 300 mm (12 in) of height. The base is 200 mm (8in) in diameter and it has a smaller opening at the top of 100 mm (4 in).

2-The base is placed on a smooth surface and the container is filled with concrete in three layers, whose workability is to be tested.

3- Each layer is temped 25 times with a standard 16 mm (5/8 in) diameter steel rod, rounded at the end.

4-When the mold is completely filled with concrete, the top surface is struck off (leveled with mold top opening) by means of screening and rolling motion of the temping rod.

5-The mold must be firmly held against its base during the entire operation so that it could not move due to the pouring of concrete and this can be done by means of handles or footrests brazed to the mold.

6-Immediately after a 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 center of the slumped concrete is called a slump.

8-The slump is measured by placing the cone just beside the slumped 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. (usually measured to the nearest 5 mm (1/4 in).

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