What Is Concrete Slump?

Being a civil engineer, you must be looking for what is a concrete slump? The slump test is performed to measure the workability or water-cement ration of freshly mixed concrete. This causes it to become weak or even crumbly concrete. In some cases, it can also mean a concrete slip. There are many ways by which this slippage can occur.

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Following are the reasons to perform concrete cone test:

  • Measure the workability of concrete
  • Measure the consistency of concrete
  • Measure the improper mixing of concrete
  • Measure the easiness of flowing

work-ability of concrete

Concrete Slump Test Code?

Equipment’s For Slump Cone Test

As mentioned above, concrete cone testing is performed to measure its consistency from batch to batch. So, it is feasible to have these cone testing concrete equipment at the site:

slump test kit

  • Slump Cone – Size: Height 30cm x Base Dia. 20 cm x Top Dia. 10cm Buy Now
  • Square Base Plate – It should be non-porous Buy Now
  • Measuring scale Buy Now
  • 16 mm Diameter x 60 mm Length Temping Rod Buy Now
  • Spatula for pouring concrete Buy Now

That’s all. You are ready to perform this test by yourself.

Concrete Slump Range?

It may vary according to specified concrete design mix by your concrete designer or where its been used like for footing, column, beams or slabs (As shown below). In general, an ideal or good slump in concrete ranges between 3 inches to 4 inches or 75 to 100 mm. Please see the chart below:

concrete slump range

Types of Slump

There are FOUR types of slumps in concrete which are:

  • True Slump – It indicates the ideal slump in concrete
  • Zero Slump – It indicates a very low water-cement ratio
  • Collapsed Slump – It indicates a very high water-cement ratio
  • Shear Slump – It indicates no result and you need to retest the concrete slump.

types of slump

Procedure for Concrete Cone Test

  1. First, mold should be cleaned via brush or water.
  2. After drying the mold, apply grease or oil so the concrete won’t stick.
  3. The cone is placed on a square base plate and holds in a firm position.
  4. Concrete is poured into three layers.
  5. Each layer should be compacted via temping rod (25 Numbers)
  6. When the cone is full, excessive concrete is struck off using a spatula.
  7. Cone is then lifted in a vertical position gently.
  8. Care should be taken in lifting as tilting can cause a change in slump value.

procedure for slump test

How to Measure Concrete Slump

It simply measures the distance between concrete slumps with original cone height.

  • Place the mold next to the wet concrete after removal.
  • Put the steel bar on top of the mold.
  • Measure the slump top from the steel bar placed on top of the mold.

Precautions for Concrete Slump Test

  • Equipment should be cleaned so that it does not alter test results.
  • A slump cone should be lifted with care in a vertical direction.
  • There should be no movement in the horizontal direction.
  • Measurement should be done immediately after removing the cone.

Every civil engineer must know about the cone testing? and how to perform on-site. It is a very important field test of concrete.