Skip to main content

Workability and slump test procedure

Short answer

Workability is the ease of mixing, placing, compacting and finishing concrete without segregation. Slump test: clean cone on base plate, fill in 4 layers, each tamped 25 times with rod, strike off, lift cone slowly in 5-10 seconds, measure vertical subsidence to nearest 5 mm. Test completed within 2 minutes.

Define workability and write down the procedure for performing the slump test.

Workability is the ease with which concrete can be mixed, placed, compacted and finished without segregation (IS 6461 Part 7).

Slump test procedure (IS 1199; IS 7320)

Apparatus: slump cone (frustum) of 300 mm height, 200 mm bottom and 100 mm top internal diameter; tamping rod 16 mm dia, 600 mm long with bullet end; base plate (non-absorbent, smooth); scale.

Procedure

  1. Clean the mould and place it on a smooth, horizontal, non-absorbent base plate; hold it down with the foot pieces.
  2. Fill the cone in four layers, each about one-quarter of the height; tamp each layer with 25 strokes of the rod, uniformly distributed, penetrating into the layer below.
  3. After the top layer, strike off the surface level with the top of the cone.
  4. Lift the cone vertically slowly (in 5-10 seconds) without any twisting.
  5. Measure the slump, the difference between the height of the mould and the height of the highest point of the subsided concrete, to the nearest 5 mm.
  6. Complete the test within 2 minutes of sampling; if the concrete shears off or collapses, the test is repeated.

Recommended slump (IS 456 cl. 7.1): 25-75 mm for lightly reinforced sections in slabs, beams, walls and columns; 50-100 mm for heavily reinforced sections; 75-100 mm for trench fill, etc.

Related questions

All Concrete Technology and Masonry Structure chapter 3 questions →