Concrete Slump Test - Explained By Converge

May 19, 2022

Concrete slump test

A concrete slump test is a commonly used test. Its purpose is to show the consistency of the fresh concrete mix. The concrete slump test gives immediate results and can also tell if the concrete mix has been blended accurately or not. This is a cheap and easy way to test concrete. The slump test is used on site to directly help determine the quality of the concrete.


When doing a concrete slump test, you take a metal cone, place it on a surface that is hard, stable and doesn't absorb anything, and then fill it up with concrete in different steps. We will explain the process further below.


Read more: What is concrete made of, concrete setting time, concrete curing time and concrete maturity


4 things that will affect the slump test of concrete

  1. The characteristics of the materials in the blend.

The characteristics determine how the consistency of the mix will be.


  1. The ratio of water and cement in the concrete blend.

If there is too much water, the mix will be loose, and if it is too little water the mix will be difficult to work with.


  1. The temperature of the mixture.

The temperature of the mix will decide how slow or fast the concrete will harden.


  1. The amount of time that has passed between the mixing and the slump test.



Equipment needed for a concrete slump test

To be able to perform a concrete slump test in a proper way, you need the following equipment:


-   A metallic mould in the shape of a cone. The measurements should be 20 cm (8 in) in diameter measured at the bottom, 10 cm (4 in) in top diameter and a height of 30 cm (12in).


-   Tamping rod in steel. This shall be 16 mm (approx. 0,63 in) in diameter and have a length of 60 cm (approx. 24 in) with one of the ends rounded.


-   Trowel.


How a concrete slump test is done

The procedure for the concrete slump test is:


  1. Get rid of all dirt on the cone-formed mould.


  1.  Use oil on the inside so the cone, this will make it easier to remove without affecting the test result.


  1. Place the cone on a flat, horizontal surface. It should not be water-absorbing and it should have a smooth base.


  1. Fill the cone with your concrete mix. This should be done four times in equally large layers.


  1. Every layer should be tamped 25 times. For this, you use the rounded end of the tamping rod. After that, you can even out the surface at the top with the trowel.


  1. Clean the surface around the cone. Take away all excess that has leaked so it is only the cone and the concrete in it left.


  1. Remove the cone from the concrete. Be careful not to destroy the test when removing.


  1. Evaluate the test.


Read more: Curious to know more about different tests of concrete? Learn more of the concrete cube test here!


Different types of results from the concrete slump test

There are four different types of results you can get from a slump test. These are:

-   Zero Slump.

If you get the result of zero slump, the concrete retains its shape completely after the cone is removed. A dry kind of mix is holding this shape.


-   Shear Slump.

The shear slump indicates that the test should be retaken.


-   True Slump.

The mix retains its shape to a large degree.


-   Collapsed Slump.

A collapsed slump means that the amount of water in the mix is too high, and the concrete is too “loose”.


Reading tips: What are concrete slabs, the difference between concrete and cement and what to keep in mind when pouring concrete in cold weather.


If you want to save time when building

With ConcreteDNA, Converge helps you to build faster. In fact, up to 30% faster! With our product, you get live data of the curing process. You can see this from any device with our wireless sensors.


ConcreteDNA will help you save both money and time on your building projects. You can save time with the predictions of when the curing will be done, because you won't have to hire staff on the weekends that stand around with nothing to do due to wrongful calculations. You will save time by being able to schedule the right people, at the right place, at the right time.


Frequently asked questions


What tools do you need to do a concrete slump test?

To be able to execute a slump test for concrete, you’ll need a metal mould shaped as a cone, a steel tamping rod, and a trowel.


Why do you do a slump test?

By doing a slump test, you can determine the quality and the workability of a concrete mix. You will also be able to see if the ingredients were proportioned wrong and if the ratio between water and cement is correct.


Is it cheap to do a slump test?

Yes! Since you only need 3 tools and the concrete mix, it is a very cheap and easy test if you want to measure the quality and workability of your concrete mix.

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