WHAT IS SLUMP TEST

SLUMP TEST OF FRESH CONCRETE

AIM:- To determine the workability of fresh concrete by slump test asper IS 1199-1959.

PRINCIPLE:- Slump test is most common used test for measuring consistency of concrete. It can be employed either in laboratory or at field.

APPARATUS AND MATERIALS:- 
  • Slump cone

It is a metallic mould in the form of frutusum of a cone with internal dimensions as follows:
Bottom diameter - 20 cm
Top diameter - 10 cm
Height of cone - 30 cm
The bottom and top ends of the mould are open, parallel to each other and right angle to the axis of cone.
  • Tamping rod which have diameter 16 mm and length 0.6 m.
  • Fresh concrete

PROCEDURE:- 
  1. The internal surface of the mould is thoroughly cleaned and free from super flurois moisture and adherence of any old set concrete before commencing the test.
  2. The mould is placed on a smooth, horizontal and non absorbent surface.
  3. The mould is filled with concrete in 4 equal layers. Each layer is tamped with 25 strokes of tamping rod.
  4. After the top layer has been tamped the concrete is stuck off the level with the trowel.
  5. The mould is removed from the concrete immediately by raising it slowly in the verticle direction.
  6. The difference in level between the height of the cone and that of the highest point of the subsided concrete is measured.
  7. This difference in height in mm is the slump of the concrete.

AFTER THE TEST WE OBTAIN SOME RESULTS LIKE FOLLOWING.
  1. True slump
  2. Shear slump
  3. Collapse slump
1. True slump:- If the concrete subsides evenly it is called true slump.

2. Shear slump:- If one half of the concrete cone slides down, it is called shear slump. The shear slump is measured as a difference in height between the height of the cone and the average value of subsided Concrete.

3. Collapse slump:- If the concrete is more leaner then it will collapse after removing cone it is called as collapse slump.


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