Slump Test for Workability of Concrete

Introduction: 

Workability of concrete is defined as the ease with which concrete is mixed; placed, compacted etc.

Slump test is most basic test which is used to measure workability of freshly prepared concrete.

Concrete is poured in a cone; then cone is lifted up, the concrete collapses.

The reduction in the height of heap of concrete is called SLUMP VALUE. Slump value is proportional to workability of concrete.

Equipment

Slump cone of standard dimensions i.e. top diameter 10cm, base diameter 20cm, height 30cm.

Standard tamping rod of 60cm length 1.5 cm diameter.

Trowel, scoop, scale etc. 

Slump Cone (Image Source)

Procedure

1. All ingredients of concrete are weighed and mixed in dry state.
2. Required amount of water is added in mixed concrete sample. Concrete is again mixed manually.
3. Freshly prepared concrete is poured in slump cone. Concrete is poured in four layers
4.  Each layer is compacted by giving 25 uniform blows by using standard compaction rod.
5. Then the slump cone is lifted up gently in vertical position.
6. Let the concrete mass take its natural position. Measure slump value of concrete by using a scale.
7. Slump value defines the workability of concrete. 

Conclusion:

1. Slump test is good and fast to be used at site.
2. No much technical skills are required to conduct this test.
3. The test is less reliable as compared to compaction factor test.
4. Not good to be use in case of stiff concrete.

Types of Slump Cones (Image)