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 exists some field test which gives us a rough idea of quality
of cement. While on site we can perform these field tests to judge the quality
of cement. These field tests are as follows:
1. Date
of packing
|
2. Color
|
3. Rubbing
|
4. Hand
into Bag
|
5. Float
Test
|
6. Smell
Test
|
7. Presence
of lumps
|
8. Shape
Test
|
9. Strength
Test
|
1. DATE
OF PACKING
Date of
manufacture should be checked before use on the bag. It is advised to use
cement within 2 months of its manufacture. It is important because the strength
of cement reduces with age.
2.
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 other material, commonly with sand.
4. HAND
INTO BAG
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. Hence, cement bags should not allow moisture in.
8.
SHAPE TEST
Take 100g
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 settling. 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*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.
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