Testing of Cement:-
- Tests are carried out to decide the quality of cement.
- Test sample is prepared by mixing of cement taken from at least 12 different points from heap (if cement is loose) or from at least 12 different begs (if cement is in beg).
- Test sample is stored in air-tight container.
- Tests for cement are:-
i. Colour
ii. Physical
properties
iii.
Presence of lumps
iv. Strength
B.
Lab
Test
i. Physical Test
1. Fineness
Test
2.
Consistency Test
3.
Initial and Final Setting Time
4.
Soundness Test
5.
Determination of Strength
6. Heat of Hydration
7.
Specific Gravity
ii. Chemical
Test
1.
Loss on Ignition
2. Chemical Composition Test
Field Tests for Cement:-
- Field tests are carried out to determine
roughly the quality of cement.
i.
Colour:- Colour of cement should be uniform grey colour.
ii.
Physical Properties:-
Ø Cement
should feel smooth between fingers.
Ø It
should feel cool, not warm if hand is inserted in a bag or heap of cement.
Ø It
should sink and should not float on the surface, if a small quantity of cement
is thrown in a bucket of water.
Ø A
thin paste of cement with water should feel sticky between fingers.
Ø The paste of cement with water should not give an earthy smell.
iii. Presence of lumps:-
Ø Cement
should be free from any hard lumps which are formed by the absorption of
moisture from the atmosphere.
Ø Any bag of cement containing such lumps should be rejected.
iv. Strength:-
Ø Briquettes
with a lean mortar 1:6 are made.
Size of briquette may be 75mm x 25mm x
12mm. The briquettes are immersed in water for a period of 3 days. If cement is
of the best quality, such briquettes will not be broken easily and it will be
difficult to convert them into power form.
Ø A
block of cement 25mm x 25mm x 200mm is prepared and immersed it in water for 7
days. It is then placed on supports 150mm apart and loaded with 340 N. The
block should show failure signs.
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