How to test for slump

The slump test is used to measure the workability of concrete. The test is performed as follows:

  1. The cone is positioned on the base plate with the smaller aperture uppermost
  2. Freshly supplied concrete is poured into the cone to approximately one third of its depth (100mm)
  3. The concrete is tamped using 25 strokes of the steel rod
  4. Further concrete is added to fill the cone to approximately two thirds depth (ie: another 100mm of concrete)
  5. Again, the concrete is tamped using 25 strokes of the rod just penetrating the layer below
  6. The cone is filled to the top and tamped using a final 25 strokes with the steel rod
  7. Using the tamping rod slid across top of the cone the surface of the concrete is “struck off” level with the top of the cone
  8. The cone is carefully lifted upwards, clear of the concrete and is placed, upside-down next to the concrete
  9. After a minute or so, the unrestrained concrete will settle downwards or “slump” due to gravity
  10. The steel rod (or other suitable straightedge) is used to span the inverted cone and towards the slumped concrete
  11. The height difference between the steel cone and the slumped concrete is measured
  12. This difference, measured to the nearest 10 millimetres, is “The Slump”.

How to test slump

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