Slump Test | Slump Cone Test | Slump Test of Concrete
What Is the Slump Test?
The slump test is conducted to measure the consistency of concrete in that specific batch. Here, consistency of concrete refers to the workability or fluidity of freshly made concrete, and therefore it is a measure of the ease with which concrete flows.
Therefore, the Concrete slump test also known as the Workability Test of Concrete is used on-site to measure the workability of concrete or the degree of fluidity in the concrete mix.
Generally, loose wet mixes are more workable than drier mixes, but concrete of the same consistency may vary in workability.
The test also shows the change of fluidity of mix between two batch mixes. The slump test of concrete is widely used in construction for a few apparatus and simple procedures.
The slump is also used to ascertain the effects of plasticizers on their introduction into the concrete mix.
Read More: Workability of Concrete | Factors Affecting Workability of Concrete
Concrete Slump Test
The Slump test concrete is carried out with the help of a conical cone open at both ends. The slump cone filled with concrete lifted up and the resulting height of concrete spread over the surface shows the degree of fluidity, workability, and consistency of the concrete mix. It also indicates the amount of water added is correct or not.
IS Code for Slump Test
- IS 1199–1959 Methods Of Sampling And Analysis Of Concrete
- IS: 7320 -1974 Specification For Concrete Slump Test Apparatus
Principle of Slump test
The Slump cone value of concrete just works on this principle of gravity flow of the surface of the concrete cone which indicates the amount of water added to it. That means how much this mixed concrete is in a condition workable.
Slump Cone Apparatus
Slump Cone Testing
The test is carried out using a conical shape metal body known as a slump cone or Abrams cone that is open at both ends and has an attached handle.
The slump cone has an internal dia. 100 mm at the top and 200 mm at the bottom and the total height of the cone is about 300 mm.
How to Measure Slump of Concrete
The slump value of concrete can be easily measured by using the slump cone test method. In which fresh concrete is poured and filled till the top.
Then the cone is lifted slowly, and the difference between the top of the cone and the top concrete fall is measured as a slump of concrete.
Slump Test Procedure
Slump Cone of concrete procedure,
- First, the slump cone is placed on a hard non — water-absorbing surface. ( metal or concrete)
- The Slump cone is filled with freshly mixed concrete in three layers.
- Each layer of the concrete mix must be tapped with a 2 ft (600 mm)-long bullet-nosed metal rod measuring 5 8 in (16 mm) in diameter.
- After filling the last layer extra concrete must be removed from the top of the cone.
- The slump cone then quickly lifted upward with a twisting effect with both hands. The concrete is then free to fall.
- After free fall the remaining height is known as slump and is measured to the nearest 5 mm if the slump is 100 mm.
Factors affecting Slump Cone Test
The following factors influence concrete Slump value:
• Quality of Fine aggregate, Coarse aggregate, its texture, grading size, moisture content, and shape of it.
• Also affect the water-cement (w/c) ration of concrete.
• Air Content of Concrete and Void ratio of concrete.
• Use of various types of admixtures such as Superplasticizer, Plasticizer admixture, and the sequence of them mixing.
• Time is also an important factor for concrete mixing.
Types of Slump
According to the free fall shape of concrete, the slump is classified into three types termed as true slump, shear slump, or collapse slump.
Types of Slump
Collapse
Shear
True
In a collapse slump, the concrete collapses completely In a shear slump the top portion of the concrete shears off and slips sideways In a true slump, the concrete simply subsides, keeping more or less to shape.
- If a shear or collapse slump is achieved, a fresh sample should be taken and the test repeated.
- Only a true slump is of any use in the test.
Standard Slump Test Values
Sr.No.
Slump
Value
Used
1
0–25 mm Road Construction
2
10–40 mm Foundations with light reinforcement
3
50–90 mm Normal reinforced concrete placed with vibration
4
> 100 mm. High workability concrete
Limitations
- The slump test is not applicable when the aggregate is more than 40 mm.
- This test does not give an accurate result for high-dry and stiff concrete.
Advantages
- It has a simple apparatus that can be performed in the laboratory as well as on-site.
- It requires fewer apparatus compared to other tests.
- Testing time is too short and gives results quickly;
FAQs:
Slump TestThe slump test is conducted to measure the consistency of concrete in that specific batch. Here, consistency of concrete refers to the workability or fluidity of freshly made concrete, and therefore it is a measure of the ease with which concrete flows.Slump Value for M20 ConcreteWorkability for the M20 grade of concrete was achieved by adopting a 0.5 water-cement ratio and a 2% superplasticizer. The slump value for M20 concrete is between 100 and 160 mm.Types of Slump TestAccording to the free fall shape of concrete, the slump is classified into three types termed as true slump, shear slump, or collapse slump.The volume of Slump ConeThe standard slump cone volume is 0.00549 cu m. or 0.1939 cu ft.Slump Cone Test IS CodeIs Code followed for Slump Cone Test is IS 1199–1959 Methods Of Sampling And Analysis Of Concrete
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