LABORATORY TESTS FOR CEMENT | Tests of cements

LABORATORY TESTS FOR CEMENT :

1. Fineness test of cement
2. Standard Consistency test of cement
3. Initial Setting and Final Setting test of cement
4. Soundness test
5. Compressive Strength test of cement

1. FINENESS TEST OF CEMENT :

• This test of cement is performed to see the fineness of cement consistent with standard specifications.

• The fineness of cement are often measured either by the grain size of cement or by the area of cement.
• The sieve Test (IS 4031- part-I) – 90 µ size sieve.
• The fineness of cement features a significant effect on the hydration and in increasing the rate of gain strength. The strength of cement is directly proportional to its fineness.

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2. STANDARD CONSISTENCY TEST OF CEMENT :

• it's wont to determine the share of water required to
produce cement paste of ordinary consistency.

• it's also sometimes called as Normal Consistency (CPNC).
• the quality consistency of a cement paste is defined as
that consistency which can permit a Vicat’s apparatus
plunger having10mm dia. and 50mm length to penetrate to
a depth of 33-35 mm from the highest of the mould.

Initial Setting time-

• When the paste will start loosing its plasticity, the needle will penetrate only to some depth.

• the amount elapsing between the time when water is added to the cement and to the time at which the needle penetrates the test block to a depth equal to 33-35mm from the highest is taken as initial time.
• For OPC it's generally taken as 30min.

Final Setting time-

• The cement is taken into account fully set when the centre needle makes an impression while the annular attachment fails to try to to so.
• The cement is claimed to be hard if it doesn't pierce quite 0.5mm.
• it's generally taken as 10 hrs.

4. SOUNDNESS TEST :

• The Cement is claimed to be unsound if it's excess of lime.
• thanks to high proportions of magnesium content or Calcium sulphate content.
• due to inadequate burning of cement.
• thanks to insufficiency in fineness of grinding or thorough mixing of raw materials.
• It cause appreciable change within the volume of cement after the cement has set causing disruption of the set and hardened mass.

• Le-Chatlier’s Apparatus is employed for the test.
• just in case the expansion is quite 10mm than the cement is claimed to be unsound.

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5. COMPRESSIVE STRENGTH TEST OF CEMENT :

• it's Laboratory method to work out the strength of cement.
• the dimensions of cube mould is 70.6mm.

• Cement and standard sand mortar is employed to make the cube.
• Three cubes are tested for the strength.
• the typical value is taken for the compressive strength of the three cubes for each period respectively.