Slump test

• Slump test is one of most extensively used test all over the world 
• Slump test does not measure workability of concrete , although it gives a measure of consistency , but is very useful in detecting variation in uniformity of mix of given nominal proportions 
• Dimensions of the mould are, bottom diameter =200 mm top diameter =100mm and hight = 300 mm 
• Mould is filled in with fresh concrete in four layers , each layers of approximately one - quarter of the height of the mould and tamped with 25 strokes of the rounded end of the tamping rod ( dia 16 mm and length 600 mm) 
• Strokes are distributed in a uniform manner over the cross section and for the second and subsequent layers should penetrate into the underlying layer 
• After the top layer has been rodded, the concrete is struck off level with a trowel or the tamping rod such that the mould is exactly filled . 
• Mould is removed immediately by raising il slowly and carefully in a vertical direction 
•  It allows the concrete to subside and the slump is measured immediately by determining the difference between the height of the mould and that of the highest ponit of the specimen being tested 
• Slump measured is recorded in terms of millimeters of subsidence of the specimen

1. Concrete for road construction = slump (mm) 20to 40 
2. Parapets ,piers,slab ,beams = 40 to 50 mm
3. Concrete for canal lining = 70to 80 mm 
4. Concrete for arch and side wall of tunnel = 90 to 100 mm
5. Normal R.C.work = 80 .to 150
6. Mass concrete = 25 to 50 mm 
7. Concrete to be vibrated  = 10 to 25 mm