Use of Slump cone test :

Slump test is most commonly used method for measuring consistency of concrete.

This is test is a control test and gives an indication of the uniformity of concrete from batch to batch.


Slump test of concrete to measure workability

Apparatus and Equipment used : Apparatus for conducting slump test essentially consists of metallic mould in the form of frustum of a cone having internal dimensions as under:-

Bottom diameter = 20 cm.

Top diameter= 10 cm.

Height 30 cm.

Thickness of metallic sheet for mould should not be thinner than 1.62 mm.

Tampering rod  diameter = 16 mm. (60 cm long bullet pointed at lower end).

Steps for Procedure:

i.The internal surface of the mould is thoroughly cleaned and applied with a light coat of oil.

ii.The mould is placed on a smooth, horizontal, rigid and non-absorbent surface.

iii.The mould is then filled in four layers with freshly mixed concrete, each approximately to one-fourth of the height of the mould.

iv. Each layer is tamped 25 times by the rounded end of the tamping rod (strokes are distributed evenly over the cross section).

v. After the top layer is rodded, the concrete is struck off the level with a trowel.

vi. The mould is removed from the concrete immediately by raising it slowly in the vertical direction.

vii.The difference in level between the height of the mould and that of the highest point of the subsided concrete is measured.

viii. This difference in height in mm is the slump of the concrete.


Result Recorded:

Slump of concrete= Height of the mould – highest point of the subsided concrete is measured.

Slump of concrete was recorded = 85 mm  

Degree of workability = Medium (True slump).


The reading was taken at site construction and it will be different for other concrete mixes.


                                                  Relation between Workability and Slump

Factors affecting Slump test of fresh concrete test:

1.     Concrete batching, mixing and transportation methods and equipment.

2.     Concrete temperature.

3.     Sampling of concrete, slump-testing technique and condition of test equipment.

4.     The amount of free water in the concrete.

5.     Mixing time of concrete at the time of testing.

6.     Physical properties such as chemistry, fineness, particle size distribution, moisture content and temperature of cement material. shape, texture, combined grading, cleaniness and moisture of aggregates.

7.     Chemical mixture dosage- composition and addition sequence.


Results of Slump Test on Concrete can be one of the following:


Figure a -Results of Slump Test on Concrete.

True Slump - True slump is the only trump that can be measured in a test. Measurements are taken between the top of the cone and the top of the concrete after the cone is removed as shown in figure a.

 Zero Slump - A zero recession is a sign of a very low water-cement ratio, resulting in a dry mixture. This type of concrete is commonly used for road construction.

 Collapsed slump - This is an indication that the water-cement ratio is too high, i.e. the concrete mixture is too wet or it is a high practicality mixture, for which a deceleration test is not suitable.

 Shear Slump – The shear slump indicates that the result is incomplete, and concrete to be retested.



§  Use hand gloves & shoes while testing.

§  Equipment should be cleaned thoroughly before testing & after testing.

§  The apparatus should remain free from vibrations during the test.

§  Petroleum jelly or oiling should be applied to the mould.

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