Posted on

concrete slump test being conducted

There are many different factors that go into ensuring a concrete mix meets the standard and requirements of the project it’s intended for. An important aspect of this  which you may have heard of is carrying out a concrete slump test. Why is a concrete slump test carried out and what does it involve? Let’s find out.

What Is A Concrete Slump Test?

Before looking more closely into the question of “why is a concrete slump test carried out”, let’s take a moment to look at what the test actually involves. A slump test is carried out before the concrete mix is poured. The test is used to check the consistency of the concrete to see how it holds together. A mould is used to compact the concrete into a cone shape from which the results of the test can be observed. Placed next to the mould cone for comparison, a rod is used to measure the height of the slump, whilst any changes in its shape are monitored.

Why Is A Concrete Slump Test Carried Out?

This important test is required to check the workability and quality of a batch of concrete before it is applied to a project. Specifically, it’s important for assessing if the ratios of the mix are correct and if any components need to be added or removed. In particular, close attention needs to be paid to the water-cement ratio. This affects the workability of the concrete, as well as the overall strength. The test provides an insight into whether or not these ratios are correct, so that the mix can be modified accordingly if required.

What Factors Influence The Test?

So we’ve answered the question of “why is a concrete slump test carried out”, but what factors influence the value of the test?

  • Size, texture, combined grading, cleanliness and moisture content of the aggregates
  • The properties of the materials, such as water content, can all influence the slump value
  • Dosage & type of the chemical admixtures
  • Air content of concrete 
  • Methods and equipment for batching, mixing and transporting concrete
  • Temperature of the concrete
  • Condition of test equipment, sampling and slump-testing technique
  • Amount of free water in the concrete 
  • Time since mixing of concrete at the time of testing

How Are The Results Read?

The results will fall into one of the following categories based on visual observations of the shape of the slump:

Zero Slump

If the concrete doesn’t move at all once the cone is removed then it shows the mix is very dry, and is probably best for commercial projects. 

True Slump

If the concrete maintains its cone shape but sinks slightly then this suggests that the mix is holding together well and doesn’t contain too much water. 

Shear Slump

If the cone leans to one side then this means that the mix has too much water in it so that it won’t stick together. If this is the case, then it will be important to alter the ratio of water to cement. 

Collapse Slump

The mix will need to be completely remade if the concrete collapses completely and isn’t able to hold its shape at all. 

Quality control is central to the processes that go into making our ready-mix concrete at Al Manaratain. Our two fully computerised batching plants enable us to make precise mixes that perfectly suit the individual requirements of our customers. Please don’t hesitate to get in touch with us to find out more about our products and services.