Field testing of cement quality

Field tests give a quick check of cement quality before use; laboratory tests (IS 4031) are needed for final acceptance.

1. Colour: uniform grey with a light greenish tinge, free from lumps.
2. Physical feel: rubbing between the fingers gives a smooth feel; a rough or gritty feel means adulteration with sand.
3. Hand thrust: pushing a hand deep into the bag should feel cool; warmth means the cement has already started hydrating.
4. Lumps: good cement has no lumps. Lumps that crush easily between the fingers may be only partly air-set (the cement is old); hard lumps mean the cement is bad.
5. Float test: a pinch dropped into a bucket of water should sink and not float (floating indicates impurities/adulteration or air-set cement).
6. Setting test (paste/pat test): make a stiff paste (w/c about 0.35) of cement and form a pat about 75 mm in diameter and 12 mm thick, with sharp edges, on a glass plate. Kept under water, it should set hard within 24 hours and keep its shape without cracks or distortion (soundness). Its initial set should not occur before 30 minutes and its final set should be within 10 hours.
7. Strength test: a block of neat cement 25 mm x 25 mm x 200 mm is cured in water for 7 days, then placed on supports 150 mm apart and loaded with 34 kg at the centre; it should not show signs of failure.
8. Fineness: a handful of cement should not leave much residue when passed through a fine (90 micron) sieve.
9. Storage and bag checks: bag weight 50 kg, date of manufacture (use within 3 months), and the manufacturer's brand and grade printed on the bag (IS 269, IS 1489).