Slump Test Of Concrete

CONCRETE TECHNOLOGY (Part 2)

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WHAT IS SLUMP TEST?

Slump test is a field test to determine the consistency as well as workability of fresh concrete. It is used mainly in construction sites. Slump test is very important to check immediate the quality of concrete. Slump test is very simple and easy to handle.It's also done with short period of time. Workability of concrete does not measured directly by this test.So,for Slump test consistency of concrete is measured which gives a general idea about the workability condition of concrete.

SLUMP TEST EQUIPMENT-

Slump test requires some equipment to perform the test. The equipment mainly used for slump test are followings.

Base Plate- This is use to hold the attachment.
Mould- This mould is known as slump cone. It is made of steel ,plastic etc.The height of the mould 12 inches (30 cm). The diameter of the base opening is 8 inches (20 cm) and top opening is 4 inches (10 cm).
Tamping Rod- Tamping Rod is mainly made of steel.This Rod is usually 24" long and has a diameter of 5/8" diameter.
Tape Measure- Standard tape should be measure for measurment.

EQUIPMENT OF SLUMP TEST

SLUMP TEST PROCEDURE-

These are the useful procedure of Slump test-

At first, Clean the internal surface of the mould and apply oil on it.

Place the mould on a horizontal non- porous base plate.

Fill the mould with the prepared concrete mix in 3 approximately equal layers.

Tamp each layer with 25 strokes of the rounded end of the tamping rod in a uniform manner. For the subsequent layers, the tamping should penetrate into the underlying layer.

Then,remove the excess concrete.

Level the surface with a trowel.

Clean away the mortar or water leaked out between the mould and the base plate.

Raise the mould from the concrete immediately and slowly in vertical direction.

The decrease in height at the centre point is measured to nearest 5mm or 0.25 inch and it is known as ‘slump’.

PROCEDURE OF SLUMP TEST

MEASUREMENT OF WORKABILITY FROM SLUMP TEST-

We can get the result from the only true slump. We can classify the result within some ranges according to the slump value.

Very low workability- slump value 0-25 mm.
Low workability- slump value 25-50 mm.
Medium workability- slump value 50-100 mm.
High workability- slump value 100-175 mm.

According to 'Fresh Concrete' by P. Bartos, slump results can be classified as given below:

No slump- slump value 0 mm or 0 inch
Very Low- sump value 5-10 mm or 0.25-0.5 inch
Low- sump value 15-30 mm or 0.75-1.25 inch
Medium- sump value 35-75 mm or 1.5-3 inch
High- sump value 80-155 mm or 3.25-6 inch
Very High- sump vaue 180 mm or 6.25 inch to collapse

According to European Standard ENV 206: 1992, workability is classified in 4 categories of S1, S2, S3 and S4. Slump ranges are:

S1- 10-40 mm
S2- 50-90 mm
S3- 100-150 mm
S4- more than 160 mm.

TYPES OF SLUMP-

TRUE SLUMP- For the true slump concrete just subsides shortly and more or less maintain the mould shape. This type of slump is most desirable.
SHEAR SLUMP- When one of the concrete mass slide down the other is called the shear slump. This is happen in lean concrete mix.
COLLAPSE SLUMP- When the slump is collapsed due to adding more water, that is known as collapsed slump.
ZERO SLUMP- For very stiff or dry mixes,that does not show any changes in slump after removing the slump cone.

TYPES OF SLUMP

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