Slump Test

Principle of Slump Test

The main purpose of slump test is to measure the workability of fresh concrete.  It measures the consistency or the wetness of concrete.

# Apparatus

1. Slump cone : frustum of cone , 300 mm of height. The base is 200 mm(8 in.) in diameter and it has a smaller opening at the top of 100 mm.

2. Scale for measurement.

3. Temping rod (steel) 15 mm diameter , 60 cm length.

PROCEDURE

1. Immediately after filling is completed and the concrete is leveled, the cone is slowly and carefully lifted vertically, an unsupported concrete will now slump.

2. The decrease in the height of the center of the slumped concrete is called slump.

3. The slump is measured by placing the cone just besides the slump concrete and temping rod is placed over the cone so that it should also come over the area of slumped.

4. The height decreased of concrete to that of mould is noted. It is noted with scale. (maximum it is measured to the nearest 5 mm (1/4 in ) .


SLUMP RESULT TESTS

1.True Slump

    True slump refers to general drop of concrete mass evenly all around without disintegration.

2. Shear Slump

     Shear slump indicates that the concrete lacks cohesion. It may undergo segregation and bleeding and thus is undesirable for the durability of concrete.

3. Collapse Slump

   It indicates that concrete is too wet and the mix is regarded as harsh and lean.

4. Zero Slump 

It indicates very low water-cement ratio, which results in dry mixes. It is a type of concrete that is generally used for road construction.

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