Wednesday, May 15, 2013

Slump Test in Civil Engineering

Workability of Fresh Concrete by Slump Test




Aim:



 To determine the workability of fresh concrete.

Apparatus required:

 1.Slump cone (dimensions are
          Top Diameter – 10cm
          Bottom Diameter – 20cm
          Height – 30cm)
2. Tamping rod
3. Oil
4. trowel

Procedure


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

·          The mould is placed on a smooth, horizontal, and rigid  surface.

·          The mould is then filled in three layers with freshly mixed concrete, each approximately to one-third of the height of the mould.

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

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

·         The mould is removed from the concrete immediately by raising it slowly in the upward direction.

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

·         This difference in height in mm is the slump value of the concrete.

·         This process is done repeatly  by adding various water contents.

 

Types of slumps:
   

           True slump

           Shear slump

            Collapse

         

Result:
   

For dry sample, the slump value will be in the range of 25-50 mm.
For wet sample, the slump value will be in the range of 150-175 mm

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