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Answer Posted / er. munesh natrrajan [ m.d. of
For the sake of convenience we will divide the methods
under following two categories as (i) Tests in Field and
(ii) Tests in Laboratory.
Tests in Field
Field tests are convenient way of primary inspection of
cement when it is used in small scale works or when decision
has to be made during purchase process. These are some of
the steps that can ensure you good quality cement while
inspection at site-
a) First cement bags should be open a little wide for
visible inspection. There should not be any lumps formation
inside the bag.
b) Put your hand inside the bag and ensure additionally
that there are not any hidden lumps. Also this activity
should give u a feel of cool sensation on your hands.
c) Take a sample of cement in your hand and rub it in
between your fingers. It should be smooth in nature.
d) Take another handful sample of cement and throw it
in the bucket full of water. Particles of cement should
float a while before sinking down.
Tests in Laboratory
Field tests only indicate that cement is not bad and can be
used for small scale works. Thus Laboratory tests are
necessary to confirm that cement is good in nature and can
even be used for important works too. Following tests are
necessary to be conducted on cement in laboratory-
a) Fineness Test-The fineness of cement can be defined
as the measure of size of particles of cement or in simple
form “Specific Surface of Cement”. This test is usually
carried out using IS sieve no.9 or 90 microns.
b) Setting Time Test- Cement when mixed with water
triggers a process which results in a hardened mass of
mixture wherein hardness gradually increases with time.
There are two setting times for cement- Initial Setting Time
(IST) or Final Setting Time (FST).It is tested using Vicat’s
Apparatus. Eg. For Portland Cement IST is around 30 mins and
FST is around 600 mins.
c) Strength Test- The strength of cement is defined in
MPa or N/mm2. For grade 33 Portland cement, strength should
be around 33MPa in 28 days. Compression test is carried out
to check the strength of cement.
d) Soundness Test- Soundness of cement can be defined
as a process in which cement does not show any considerable
change in volume after setting. Autoclave tests and Le
Chateleir tests care carried out to check the soundness of
cement.
e) Heat of Hydration Test- The heat of hydration can be
defined as heat from cement paste liberated as a reaction of
water with cement. This test is usually carried out in
thermos flask.
f) Chemical Composition Test- A test is carried out on
cement that tests the ratio of chemicals in the cement.
Different standards and codes specify different value of
such ratios. A standard oxide and chemical composition of
Portland cement is as given below-
Chemical Compound
Percentage
Lime, Cao
60%-66%
Silica, Sio2
17%-25%
Alumina,Al2O3
3%-8%
Iron Oxide, Fe2O3
0.5%-6%
Magnesia, MgO
0.5%-4%
Sulphur trioxide, SO3
1%-2%
Alkalis
0.5%-1.3%
Four main compounds that are present in cement and
percentage of which decides (one of the parameter) the
quality of cement are as follows-
1. Tricalcium Silcate
2. Dicalcium Silicate
3. Trialcium Aluminate
4. Tetracalcium Alumino Ferrite
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