Slump and Compaction Factor Test
 |
| Slump and Compaction Factor Test |
1. Slump Test:
• Most common method
• Frustum having top diameter 10cm, bottom
dimension around 20 cm, height of 30 cm
• Concrete to be tested in filled in the mould
in four layers where each layer is
compacted 25 no of times with the help of
rod
• Mould is removed immediately by lifting it
in upward direction which causes the
concrete to subsidize and the subsidence of
the concrete is referred as slump which may
also defined as difference of the height of
the mould and the top level of the subsidize
concrete.
Higher the value of Slump, more is the
workability
• This test is not suitable for the concrete which
process either very high workability or very low
workability.
• It is not a suitable method for very wet or very
dry concrete
• If the concrete slumps evenly it is called true
slump.
• If one half of the cone slides down, it is called
shear slump.
• In case of a shear slump, the slump value is
measured as the difference in height between
the height of the mould and the average value
of the subsidence. Shear slump also indicates
that the concrete is non-cohesive and shows the
characteristic of segregation
2. Compaction Factor Test:
• It is more precise and sensitive than slump test
• This test is used for the concrete possessing
medium and low workability for which slump
test is not suitable.
• Principle of this test is based upon finding the
degree of compaction achieved by the standard
amount of work done by the concrete when
allowed to fall from known height
• This degree of compaction is represented in
terms of compaction factor that represents the
density ratio : Density of concrete obtained
during test to the Density of fully compacted
concrete
Compacting Factor=
Weight of partially compacted concrete/
Weight of fully compacted concrete
