A self compacting concrete has the properties such as filling ability, passing ability and segregation resistance. Various workability tests methods are available for self compacting concrete such as slump flow tests, V-funnel test, L-box test, U-Box test, Fill box test etc.
Test Methods for Self Compacting Concrete
The tests methods presented here are devised specifically for self compacting concrete. Existing rheological test procedure have not considered here, though the relationship between the results of these tests and the rheological characteristics of the concrete is likely to figure highly in future work, including standardization work.
In considering these tests there are number of points which should be taken into account:
- There is no clear relation between test results & performance on site.
- There is little precise data, therefore no clear guidance on compliance limits.
A concrete mix can only be classified as self compacting concrete if the requirements for all the following three workability properties are fulfilled.
- Filling ability
- Passing ability and
- Segregation resistance.
Filling Ability of Self Compacting Concrete
It is the ability of SCC to flow into all spaces within the formwork under its own weight. Tests, such as slump flow, V-funnel etc, are used to determine the filling ability of fresh concrete.
Passing Ability of Self Compacting Concrete
It is the ability of SCC to flow through tight openings, such as spaces between steel reinforcing bars, under its own weight. Passing ability can be determined by using U-box, L-box, Fill-box, and J-ring test methods.
The self compacting concrete must meet the filling ability and passing ability with uniform composition throughout the process of transport and placing.
Workability of Self Compacting Concrete
Test methods to determine workability of Self Compacting Concrete are:
The slump flow test is used assess the horizontal free flow of self compacting concrete in the absence of obstructions. The test method is based on the test method for determining the slump
V funnel test on self compacting concrete is used to measure the flowability. But the flowability of concrete is affected by its other properties as well which may affect the flowability of the concrete during testing.
3. L Box Test
This test assesses the flow of the concrete and also the extent to which it is subjected to blocking by reinforcement.
4. U Box Test
U Box test is used to measure the filing ability of self compacting concrete. U box test was developed by the Technology Research Centre of the Taisei Corporation in Japan. Some time the apparatus is called a “box shaped” test.
Fill box test is also known as ‘Kajima test’ is used to measure the filling ability of self compacting concrete with a maximum aggregate size of 20 mm.