WHICH LABORATORY TESTS ARE CONDUCTED TO CHECK QUALITY OF CEMENT

The following important tests are carried out for normal setting of portland cement :

1. Fineness test :
This test is conducted to check the proper grinding of cement. The fineness of cement is rested either by sieve method or air permeability method.
The percentage of residue left after sieving good portland cement in 90 micron IS(Indian standard) sieve should not exceed 10%.
A good portland cement should not have specific surface less than 2.25 sq.cm/kg, if found by air permeability method.

2. Consistency test :
This test is conducted to determine the percentage of water required for preparing cement paste of standard consistency. The consistency test is performed with the help of vicat's plunger apparatus which determines the initial and final setting time and normal consistency of portland cement.
The initial setting time of ordinary and rapid hardening cement should not be less than 30 minutes.
The final setting time of ordinary and rapid hardening cement should not be more than 600 minutes.
The normal consistency of portland cement is about 25%.

3. Soundness test :
This test is carried out to determine the presence of uncombined lime and magnesia in cement which causes the expansion of cement.The soundness of cement is tested with Le chatelier apparatus. According to Indian standard specification, The expansion should not exceed 10 mm for any type of portland cement.

4. Tensile strength test :
This test is carried out on standard specimens made of good portland cement and standard sand (Ennore) With ratio of mortar 1:3 To determine the tensile strength of cement.
The average tensile strength of cement after 3 and 7 days of curing should not be less than 2 N/mm2 and 2.5 N/mm2 respectively.

5. Compressive strength test :
This test is carried out on standard cubes made of good portland cement and standard sand (Ennore) with the proportion ratio of 1:3 to determine the compressive strength of cement. According to Indian standard specifications, the average compressive strength for three cube should not be less than 11.5 N/mm2 and 17.5 N/mm2 after 3 and 7 days of curing respectively. 

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