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Workability of Fresh Concrete by Slump Test

WORKABILITY
Slump test is used to determine the workability of fresh concrete. Slump test as per IS: 1199 – 1959 is followed.The apparatus used for doing slump test are Slump cone and Tamping rod.

Procedure to determine workability of fresh concrete by slump test.
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 nonabsorbent 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.

slump-test-fresh-concrete

Reporting of Results
The slump measured should be recorded in mm of subsidence of the specimen during the test. Any slump specimen, which collapses or shears off laterally gives incorrect result and if this occurs, the test should be repeated with another sample. If, in the repeat test also, the specimen shears, the slump should be measured and the fact that the specimen sheared, should be recorded.

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Typical Questions
Ques 1. What is the ideal value of slump?
Answer 1
In case of a dry sample, slump will be in the range of 25-50 mm that is 1-2 inches. But in case of a wet concrete, the slump may vary from 150-175 mm or say 6-7 inches. So the value of slump is specifically mentioned along the mix design and thus it should be checked as per your location.

Slump depends on many factors like properties of concrete ingredients – aggregates etc. Also temperature has its effect on slump value. So all these parameters should be kept in mind when deciding the ideal slump

Ques 2. How does a superplasticizer effect the slump of concrete?
Answer 2
Value of Slump can be increased by the addition of chemical admixtures like mid-range or high-range water reducing agents (super-plasticizers) without changing the water/cement ratio.

Ques 3. How much time one should take to raise the cone?
Answer 3 Once the cone is filled and topped off [ excessive concrete from top is cleared ] raise the cone within 5-10 seconds.

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Ques 4. What are the dimensions of the cone used in Slump Test?
Answer 3
The dimensions are
Top Diameter – 10cm
Bottom Diameter – 20cm
Height – 30cm

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Kanwarjot Singh

Kanwarjot Singh is the founder of Civil Engineering Portal, a leading civil engineering website which has been awarded as the best online publication by CIDC. He did his BE civil from Thapar University, Patiala and has been working on this website with his team of Civil Engineers.

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150 comments on "Workability of Fresh Concrete by Slump Test"

Manoj Bhola says:

What will be the slump value for column,slab,Retaining wall,footing,piers?

hirwa says:

for slump test must known the workability of concrete bt we tolk. about compression test

Ajit kumar sahu. says:

The slump value of concrete should be lie between 25mm to 125mm.

vm sounthararajan says:

if i used pumping of concrete with steel fibres, any slump losss there or not

Pritish Gupta says:

How to do determine the slump of a concrete. Who tells you which slump is appropriate and why?

Manoj kumar says:

What is the reason if slump of a mix for design comes approximately same after 30 min.and 60 min.?

kry sok heng says:

i want the appropriate slump value for casting the precast T-girder.

vikas.Patil says:

At 120mt what type of do we use

SURENDAR says:

what is proportion of mix for conducting slump test

rajat says:

you should use the propotions which you got from mix design of concrete.There is no particular praportion.

alex says:

good……thanks…..

Samsul Islam says:

What is VEBE Consistometer and Specifications Limits…

Sovann says:

What is the differences between low workability and high workability?

mansingh pawar says:

For slump test must the workability of concrete

abhishek says:

what is allowable slump for slab and beam concrete???

subrat singh says:

what is ratio of slum test ?????????

SANDEEP BANSAL says:

How presence of particles below 150micron in fine aggregate effects workability of a design mix concrete?

NIRANJAN says:

how to cal slump cone volume

palash says:

within how much time the slump test should be complete???

Bharat Chaudhary says:

between 25mm to 75mm

AMIT KUMAR says:

HOW MUCH THE TOLERANCE IN THE SLUMP TEST (+) OR (-)

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