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OPC 43 :- The 43 grade OPC is the most popular general-purpose cement in the country today. The production of 43 grade OPC is nearly 50% of the total production of cement in the country. This OPC43 continues to gain strength after 28 days.

OPC 53 :- The 53 grade OPC is higher strength cement to meet the needs of the consumer for higher strength concrete. As per BIS requirements the minimum 28 days compressive strength of 53 grade OPC should not be less than 53 Mpa. Therefore, there is a vast difference in setting time of these cements. It sets very quicker and has low initial setting time. These types of cement can be used where rapid hardening is not needed.

The purity of cement can be checked by following ways :-
1. RUBBING :- Take a small quantity of cement between your fingers and rub it. It must feel smooth while rubbing but if it feels rough than adulteration with sand.

2. HAND INSERTION :- Insert your hand into the cement bag and it should give cool feeling. Hence this cool feeling indicates that there is no hydration reaction is taking place in the bag.

3. FLOAT TEST :- It is tested by throwing a small quantity of cement in a bucket of water. Thus it should sink and should not float on the surface.

4. SMELL TASTE :- Take some quantity 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.

5. PRESENCE OF LUMPS :- See that the lumps should not be present in the bag while opening the bag. Thus it ensures that no setting has taken place.

6. COLOUR :- Basically, the cement should be uniform in colour. Generally the colour of cement is grey with a light greenish shade. The colour of cement gives an indication of excess lime or clay and the degree of burning.

7. DATE OF PACKING :- Date of manufacturing should be seen on the bag. It is most important because the strength of cement reduces with age.