The main purpose of the slump test is to measure the workability of fresh concrete. It measures the consistency or the wetness of concrete. Apparatus required, procedures and results for the slump test are:
1. Slump cone (frustum of a cone) whose height is 300 mm of height, the base is 200 mm(8 inches) in diameter and has a smaller opening at the top of 100 mm.
2. Scale for measurement.
3. Temping rod (steel) of 15 mm diameter and 60 cm length.
PROCEDURES OF SLUMP TEST
1. Fill the slump cone with concrete that is needed to be tested.
2. Immediately after filling is completed; the concrete is levelled. Then the cone is slowly and carefully lifted vertically, an unsupported concrete will now slump.
3. The decrease in the height of the centre of the slumped concrete is called a slump.
4. The slump is measured by placing the cone just beside the slumped concrete and the tamping rod is placed over the cone so that it comes over the area of slumped.
5. The height decreased of concrete to that of mould is noted. It is noted with scale. (maximum it is measured to the nearest 5 mm (1/4 in).
RESULT OF SLUMP TEST
True slump refers to a general drop of concrete mass evenly all around without disintegration.
2. Shear Slump
Shear slump indicates that the concrete lacks cohesion. It may undergo segregation and bleeding and thus is undesirable for the durability of concrete.
3. Collapse Slump
It indicates that concrete is too wet and the mix is regarded as harsh and lean.
4. Zero Slump
It indicates a very low water-cement ratio, which results in dry mixes. It is a type of concrete that is generally used for road construction.
PDF Book of slump test containing all details and procedures – Click here