It is necessary to check the quality of cement on site at the time of preliminary inspection. It is not possible to check all the engineering qualities of cement on site but there exist some field test which gives us a rough idea of quality of cement. When on site we can perform these field tests to judge the quality o f cement. These field tests are as follows :-
1. Date of Packing
2. Color
3. Rubbing
4. Hand Insertion
5. Float Test
6. Smell Test
7. Presence of Lumps
8. Shape Test
9. Strength Test
Field Tests on Cement
1. Date of Packing
Date of manufacturing should be seen on the bag. It is important because the strength of cement reduce with age.
2. Color
The cement should be uniform in color. In general the color of cement is grey with a light greenish shade. The color of cement gives an indication of excess lime or clay and the degree of burning.
3. Rubbing
Take a pinch of cement between fingers and rub it. It should feel smooth while rubbing. If it is rough, that means adulteration with sand.
4. Hand Insertion
Thrust your hand into the cement bag and it should give cool feeling. It indicates that no hydration reaction is taking place in the bag.
5. Float Test
Throw a small quantity of cement in a bucket of water it should sink and should not float on the surface.
6. Smell Test
Take a pinch of cement and smell it. If the cement contains too much of pounded clay and silt as an adulterant, the paste will give an earthy smell.
7. Presence of Lumps
Open the bag and see that lumps should not be present in the bag. It will ensure that no setting has taken place.
8. Shape Test
Take 100 g of cement and make a stiff paste. Prepare a cake with sharp edges and put on the glass plate. Immerse this plate in water. Observe that the shape shouldn’t get disturbed while setting. It should be able to set and attain strength. Cement is capable of setting under water also and that is why it is also called “hydraulic Cement”
9. Strength Test
A block of cement 25 mm x 25 mm and 200 mm long is prepared and it is immersed for 7 days in water. It is then placed on supports 15000 mm apart and it is loaded with a weight of 340 N the block should not show any sign of failure.
