What is the Slump Test of Concrete?

The Slump test of concrete is performed for measuring the workability of concrete and extensively used in construction site-work all over the world. The test procedure is taken from IS 1199 (1959).

Concrete slump test is an on-the-spot test to determine, indirectly, the correct W/C ratio needed for concrete to be used for different works. Fresh unsupported concrete will flow to the all sides and the vertical sinking of concrete is known as the slump. A concrete is said to be workable if it can be easily placed compacted and easily mixed and easily finished.

What is Slump Cone?

The slump cone is a hollow frustum made from thin steel sheet with internal dimensions as its top diameter is 10cm, the bottom diameter is 20 cm, and height is 30 cm in the test slump cone stands on a plane non-porous surface. To facilitate vertical lifting from molded concrete it is provided with a suitable guide attachment and suitable foot places and suitable handles. The tamping rod is of 16mm diameter and 60cm long and it is bullet pointed at the lower end.

Slump Test of Concrete as per IS 1199 | Workability of Concrete

 

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Hi friends, you are welcomed in the world of Civil Allied Gyan. Read definition, apparatus, IS code, procedure, formula, result, observation and lab report for slump test of concrete to find workability of concrete.

By the help of this you can easily find the workability of concrete by slump cone test.

IS Code for Slump Test of Concrete:-

• IS: 456-2000; Code for plain and reinforced concrete
• IS: 1199-1959; Code for methods of sampling and analysis of concrete

Apparatus Required For Slump Test of Concrete:-

• Iron Pan for mixing concrete
• Weighing balance
• Trowel
• Wire brush
• Slump Cone
• Steel scale
• Tamping rod
• Mixing tray

Internal Dimension of Slump Cone:-

Details	Dimensions in cm	Tolerance in mm
Bottom diameter	20	+3, -1∙5
Top diameter	10	+3, -1∙5
Height	30	±1∙5

Specification about Slump Cone:-

The slump cone should not be constructed of metal (Don’t use the slump cone made by brass or aluminium) of at least 1.6mm (or 16BG) thickness. The top and bottom shall be open at right angle to the axis of the cone. The slump cone should have a smooth internal surface. It shall have suitable foot pieces and also handles to facilitate lifting it from the moulded concrete test specimen in a vertical direction as required by the test. Dimension of the slump cone should not differ by more than the specified tolerance. A typical slump cone is shown in the figure.

Procedure for Slump Test of Concrete:-

1. Preparation of Specimens:- Mixtures are prepared with W/C ratio 0.4, 0.5, 0.55 and 0.6. For each mixtures, take Cement = 2.5 kg, C.A. = 10 kg and F.A. = 5 kg.
2. Mix the dry constituents thoroughly to get a uniform colour then add water in the mixture.
3. The internal surface of the mould is to be completely cleaned and placed on a smooth, horizontal and non-absorbent surface.
4. Place the mixed concrete in the completely cleaned slump cone in 4 layers. Each is approximately ¼ in height of the mould.
5. Tamp each layer 25 times with tamping rod using the tampering rod or a trowel strike of the excess concrete above the concrete slump cone.
6. Measure the vertical height of cone (h₁).
7. Immediately after this, slowly and carefully remove the slump cone in the vertical direction.
8. As soon as the slump cone is removed the concrete settles in vertical direction.
9. Place the steel scale above top of the settled concrete in horizontal position and measure the height of slump cone (h₂).
10. Complete the experiment in two minutes after sampling.
11. The difference of two heights (h₁-h₂) gives the value of slump. 

Observations:-

1) Type of cement = ……………….

2) Brand of cement = ………………

3) Density of concrete= ............... kg/Liter

Observation Table:-

Trail No.		Proportion				Slump in mm	Types of Slump
	W/C	W liter	C kg	FA kg	CA kg
1
2
3
4

Reporting of Result:-

The slump of concrete = …………….mm

Specifications:-

The degree of workability of concrete as per IS: 456-2000 is classified as follows:

Degree of workability	Value of slump
Very low	0mm to 25mm
Low	25mm to 50mm
Medium	50 mm to 100 mm
High	100 mm to 175 mm

Relation between workability, compaction factor and slump:-

Workability	Compaction Factor	Slump (mm)
Very Low	0.78	0-25
Low	0.85	25-50
Medium	0.92	50-100
High	0.95	100-175

Read also:- 

Workability of concrete by vee-bee consistometer test;

Workability of concrete by compacting factor test

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