Flow table test of concrete is a laboratory test, which became widely used in recent times. Flow table test comes in use, particularly for the flowing concrete made by the effect of the usage of superplasticizers.
- Aim of Flow Table Test
- IS Code for Flow Table Test
- Principle of Flow Table Test
- Significance of Flow Table Test
- Apparatus for Flow Table Test of Concrete
- Materials for Flow Table Test of Concrete
- Precautions for Flow Table Test of Concrete
- Flow Table Test Procedure as Per IS Code
- Observation of Flow Table Test
- Calculation of Flow Table Test
- Result of Flow Table Test
- Conclusion of Flow Table Test of Concrete
- Use of Flow Table Test
- Flow Table Test at a Glance
Aim of Flow Table Test
Flow table test is done for “determining the workability/consistency of the concrete mix.”
IS Code for Flow Table Test
IS : 1199 – 1959 Methods of Sampling and Analysis of Concrete
Clause 5.3 – Flow test of cement concrete by the use of the flow table
Principle of Flow Table Test
Flow table test measures the following three aspects of the quality of concrete: consistency, cohesiveness, and the tendency of the concrete mix to segregate.
Flow table test measures the flow of the concrete (as suggested by its name itself). This flow characteristics of concrete are one of the aspects of workability. Thus, the flow table test can be used to measure the workability of the concrete mix.
Significance of Flow Table Test
Importance of flow table test of concrete is given below:
- Flow table test measures the flowability of concrete giving a measure of its workability.
- For highly workable concrete, the flow table test is impeccably suitable.
Apparatus for Flow Table Test of Concrete
Flow Table Test Apparatus is described below:
1. Flow Table Apparatus
The flow table apparatus has a steel plate fixed over a wooden board with a net mass of 16 kg (35lb). The wooden board is hinged at the side to the baseboard. The size of each of the boards is 700 mm (27.6”).
The upper board can be lifted such that its free edge rises for 40 ± 1 mm (1.6”). The location of placing concrete on the table is marked with proper indications on the apparatus.
Let’s tabulate the dimensions of the flow table top below:
|Length, width, & thickness of flow table top||700 * 700 * 1.5 mm3|
|Diameter of the central circle on the tabletop||200 mm|
|Diameter of the central circle on table top||16 ± 1 kg|
The mould should be in the shape of a hollow frustum of a cone and made of metal casting. Handles should be present on the mould.
The dimensions of the frustum mould are:
|Base diameter||25 cm|
|Upper surface diameter||17 cm|
|Thickness||≮ 1.5 mm|
3. Iron Pan
Iron pan is required to prepare the concrete mix.
4. Tamping rod
A straight metal rod shall be used for the flow table test.
Specifications of this circular rod are:
– diameter = 1.6 cm
– length = 61 cm
– one of the ends should be rounded
Materials for Flow Table Test of Concrete
- Concrete mix
Precautions for Flow Table Test of Concrete
- Concrete has a tendency to segregate as it may spread out on the table.
- The maximum nominal size of aggregates should not exceed 38 mm as in the slump test.
Flow Table Test Procedure as Per IS Code
- Just before carrying out the flow table test, wet and clean the table top and the inside of mould of all the gritty materials. Remove the excess water with the help of a rubber squeezer.
- Place the frustum mould on the centre of the table and secure it firmly.
- Fill half of the frustum mould with cement concrete.
- Apply 25 strokes such that they are uniformly distributed over the cross-section of the mould.
- Fill the mould completely and again apply 25 uniformly distributed strokes such that these strokes penetrate the bottom layer.
- Struck off the extra concrete to obtain a smooth levelled surface on the top.
- Overflowed concrete out of the mould to the table should be cleaned off.
- Remove the frustum mould immediately by applying a steady pull on it.
- Then after, raise the flow table by 12.5 mm and then drop it. This process should be repeated for 15 times in 15 seconds.
- Measure the diameter of the spread concrete along the direction parallel to the flow table edge. Measure the diameter parallel to the other side of the flow table too.
- Calculate the average of the two diameters to the nearest 5 mm.
- Calculate flow value in percentage.
Observation of Flow Table Test
Note the flow of concrete by recording the spread diameter of the concrete.
Spread diameter of the concrete along one edge d1 = _______ mm
Spread diameter of the concrete along the other edge d2 = _______ mm
Calculation of Flow Table Test
Flow table test formula is:
Result of Flow Table Test
Flow value of the concrete mix is ________ %.
The flow value of the concrete mix ranges from 0-150 %.
Conclusion of Flow Table Test of Concrete
Flow table test considers the flowability property of the workability of the concrete mix. The higher the flow value, the more the flowability, i.e., the workability of the concrete.
Use of Flow Table Test
When highly workable concrete is to be used at the site, then the flow table test as a measure of workability is quite useful.
Highly workable concrete is required at –
- Hot weather concreting
- Places where complete compaction is not possible owing to limited space availability
- Members of RCC having congested reinforcement
Flow Table Test at a Glance
|Clean the table top before commencing the test.|
|Clean the tabletop before commencing the test.|
|Fill the mould in 2 layers and apply 25 strokes uniformly after each filling. Smoothen the top surface and clean the overflowed concrete on the table.|
|Remove the mould immediately carefully. Raise and drop the table to a height of 12.5 mm. Repeat this for 15 times in 15 seconds.|
|Secure the frustum mould on the table centre.|
What is the difference between slump test and flow table test?
|SR No||Slump Test||Flow Table Test|
|1||Slump test is mostly employed at the site.||Flow table test is mostly used in laboratories.|
|2||Slump test measures the||Flow table test measures the flowability of concrete.|
|3||Slump cone is sued in slump test.||Flow table apparatus consisting of wooden board hinged to baseboard is used.|
|4||Slump||Flow table test is employed for highly workable concrete.|