What is slump ?

Background :
Concrete is a mixture of cement, sand , aggregate and water.
[ For specific purpose , additives are also added in this mixture.]
Together , it forms a solid mass which is known as concrete.
The measure of water in the concrete is stated by water /cement ratio .
[ W/C.]

Definition :
The slump indicates the flow of concrete.
Slump value indicates the quantity of water added in the concrete.

Before reading further , it is suggested that you have a view of this video :
Slump of concrete
Cement and water react with each other and is known as a hydration process. The heat is evolved during the hydration process and hence it is known as the exothermic process.

A certain quantity of water is necessary for the hydration process.
If adequate water is not added in the concrete , then the hydration process shall not take place. At the same time , if excess water is added , still , there the strength shall deteriorate.

Why more water is added to concrete ?
At the junctions of beam and slab or beam and columns or beam, slab and columns , the reinforcement gets congested .Because of this , the gap between the bars is quite less. the concrete must flow through this gap. If the concrete does not flow, then there shall be honeycomb in the concrete.

Points to remember :
More water means lesser strength of concrete.

What is the solution for this ?

More water in the concrete is quite convenient for the flow.But , more is the water , lesser is the concrete strength. This issue is solved by adding plasticizer in the concrete. Plasticizer acts as an lubricant and improves the flow of concrete.

The flow of concrete is also known as workability of concrete.

The measure of flow of concrete at site is done with the help of a slump cone.
The workability of concrete is measured with slump.

This value of slump is measured by the slump cone.
There are two main categories of concrete :
Pumpable concrete and Dumpable concrete
If the concrete is to be pumped with a concrete pump , we need a concrete with higher slump and this is called a pumpable concrete .
Whereas , if the concrete is shifted to the specific location by hand trolleys , it is called as dumpable concrete and it is with a lesser slump.


In case you would like to see the actual video of how the slump cone is filled up at the site , you can see this video.
here is the link.

Measuring slump at site.


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