Introduction to Slump Test of concrete:
We conduct the Slump test of the concrete to know the workability of the fresh concrete.
After conducting the test, we could know whether the fresh concrete is worth pumping or pouring in formwork or not, Whether the water-cement ratio is in limit or not.
If the slump is too low for pumping, then it cannot reach its destination by pumping and if the slump is too low for pouring then it will not be compacted perfectly in a reinforced concrete structure, which will lead to the creation of honeycomb.
If the slump of the fresh concrete is too high and above the permissible limit then there are few problems with the water-cement ratio or the physical properties of aggregates or cement, hence the fresh concrete will give the desired strength.
Apparatus required for the slump test:
We need the following Apparatus for the Slump Cone test to know the workability of concrete
1. A Slump Cone of Height – 300mm, Bottom Diameter – 200mm, and Top Diameter – 100mm.
2. Tapering rod of 16mm diameter and 600mm long.
3. The Baseplate for the slump cone.
The procedure of slump test:
As we conduct the test to know the workability of concrete, we did not get a lab-like environment for the slump test at the construction site, so first we have to find out a plane & leveled area for the slump test and arrange all apparatus at that place start the slump test as per the procedure mentioned below.
You can also refer to the video below for detailed procedure.
Before starting the slump test make sure that the place is free of vibration & the surface of the slump cone is not sticky.
· Place the base plate on a leveled area.
· Fix the Slump cone with the base plate.
· After fixing the slump cone with the base plate start filling fresh concrete inside the slump cone.
· The slump cone should be filled in four layers.
· Each layer should be tapped twenty-five (25) times with the help of a 16mm diameter tapering rod.
· After filling the slump cone, it should be tapped properly till the bottom of the cone with the help of the tapering rod.
· Remove the loose concrete & finish the top surface of the slump cone.
· Now to lift the slump cone unscrew the cone from the base plate and lift the slump cone carefully.
· After lifting the slump cone the cone-shaped concrete will change its shape as per its workability.
· To know the slump value, we should measure the distance from the top of the slump cone to the top of the slumped concrete.
For conducting the Slump test, we Follow the following codes:
IS 1199-1959 &IS 7320-1974 in India or ASTM C143 in US or EN 12350-2 in Europe
Slump tests must be carried out at the site to maintain the quality of the concrete. Cubes should be filled for compressive strength test should be done only after getting satisfactory slump value.