Grades of Cement 33-Grade, 43-Grade, 53-Grade

Cement is widely used construction material all around the world. Cement is binder having adhesive and cohesive properties. Cement are hydroscopic, means they react in the presence of moisture. Cement is rarely used on its own.

It is mostly used in combination with other filler aggregates like fine and coarse aggregates in the presence of water, thus binding the aggregates together to form a cohesive matrix.

1. Significance – Grade of Cement

Binder strength is very important in order to incorporate some strength properties to the cement composites which may be concrete, mortar or cement plaster. Strength of cement is vital for achieving good binding and providing enough strength.

1. The higher the strength of the cement binder, the higher the strength of the member will be, provided all other factors are kept constant.
2. The lower the strength of the cement binder, the lower the strength of the casted member will be.
3. Higher the grade of the cement, higher will be the members’ strength.
4. Lower the grade of the cement, lower will be the members’ strength.

2. What are the Grades of Cement?

Normally, Ordinary Portland Cement (O.P.C.) is used in conventional construction of buildings, bridges, highways, over-head water tanks, etc. Portland Cement has been categorized based on strength into the following;

1. Grade-33 Cement
2. Grade-43 Cement
3. Grade-53 Cement

3. The Standard Codes to Follow

• ASTM C109 – Compression Test of Hydraulic Cement Mortars
• IS: 269-2015 – Specifications for 33, 43 and 53 grade OPC
• IS: 2250 – Compressive strength test for cement mortar cubes

4. How Cement is Graded?

Cement as a binder is graded based on the compressive strength of the standard cube that is casted, placed for curing for 28-days and tested for the compressive strength. Compressive strength can be calculated as per the following mentioned formula;

4.1 Formula for Compressive Strength

Compressive strength = Load Carried by the Cube / Load Carrying Area of the Cube

4.2 Units of Compressive Strength

• In F.P.S., Loads can be in lbs. (pounds) and the area can be in in2 (square-inches). Thus the unit of compressive strength in F.P.S. comes to be lbs./in2 (pound per square inches).
• In S.I., loads will be measured in N (newton), while area will be measured in mm² (square-millimeters). Thus, in S.I., unit of compressive strength will be N/mm² (newton per square millimeter) which is equal to 1 Mega-Pascal. Remember, 1 Pascal = 1 N/m².

5. Grade of Cement: 33-Grade

This type of cement is rarely manufactured by the cement industry as its use is reduced. Grade-33 Cements means a standard cube of 50mm x 50mm x 50 mm or 50 mm³ is casted and demolded after 24 hours and further kept in submerged under water for 28 days, and tested for compressive strength under the Universal Testing Machine (UTM), after drying the surface.

5.1 Strength of Grade-33 Cement

If the cube of cement has 33 N/mm² strength with 5% above or below, that may be considered as Grade-33 Cement.

5.1.1 Minimum Compressive Strength – Grade-33 Cement

The minimum compressive strength of Grade-33 Cement as recommended by standard codes are as follows;

• 3 Day: 16 N/mm²
• 7 Day: 22 N/mm²
• 28 Day: 33 N/mm²

5.2 Use – Grade-33 Cement

This type of cement was used for slab on grade i.e. slab supported by the ground, mass concreting, plain cement concreting, plastering, etc. But as the higher grades cements were manufactured sooner, hence, with advancement now Grade-43 Cement has been discarded by the industry.

Grade-33 may not suitable for concrete grade above M20.

5.3 Availability – Grade-33 Cement

• In Pakistan, Grade-33 is not manufactured at all.
• However, in India, only few cement manufacturing companies may provide such grade and certainly based on ordering / demand.
• Latest books and research literature have discarded writing and researching about Grade-33 Cement, respectively.

6. Grade of Cement: 43-Grade

This type of cement is commonly manufactured by the cement industry as its use is common and conventional. Grade-43 Cements means a standard cube of 50mm x 50mm x 50 mm or 50 mm³ is casted, and then demolded after 24 hours, and after demolding sample is kept submerged under water for 28 days, until tested against the compressive strength with the help of the Universal Testing Machine (UTM), after drying the surface.

6.1 Strength of Grade-43 Cement

If the cube of cement has 43 N/mm² strength with 5% above or below, that may be considered as Grade-43 Cement.

6.1.1 Minimum Compressive Strength – Grade-43 Cement

The minimum compressive strength of Grade-43 Cement as recommended by standard codes are as follows;

• 3 Day: 23 N/mm²
• 7 Day: 33 N/mm²
• 28 Day: 43 N/mm²

6.2 Use – Grade-43 Cement

• This grade of cement was used for slab on grade, mass concreting, plain cement concreting, plastering, reinforced concrete, etc.
• It is also used for precast concrete in tiles, blocks, pipes, etc. 
• It is suitable up to M30 grade of concrete. Above M30 grade of concrete, grade-53 cement is recommended.

6.3 Availability – Grade-43 Cement

In Pakistan and India, Grade-43 is manufactured by all cement manufacturing companies.

7. Grade of Cement: 53-Grade

This type of cement is commonly manufactured by the cement industry as its use is common and conventional. Grade-53 Cements means a standard cube of 50mm x 50mm x 50 mm or 50 mm³ is casted, and then demolded after 24 hours, and after demolding sample is kept submerged under water for 28 days, until tested against the compressive strength with the help of the Universal Testing Machine (UTM), after drying the surface.

7.1 Strength of Grade-53 Cement

If the cube of cement has 53 N/mm² strength with 5% above or below, that may be considered as Grade-53 Cement.

7.1.1 Minimum Compressive Strength – Grade-53 Cement

The minimum compressive strength of Grade-53 Cement as recommended by standard codes are as follows;

• 3 Day: 27 N/mm²
• 7 Day: 37 N/mm²
• 28 Day: 53 N/mm²

7.2 Use – Grade-53 Cement

• This grade of cement was generally used for reinforced cement concrete, prestressed concrete, bridge piers, piles, piles caps, etc.
• It is also used for precast concrete in reinforced slabs, reinforced beams and columns, etc. 
• It is suitable above M25 grade of concrete.

7.3 Availability – Grade-53 Cement

In Pakistan and India, Grade-53 is manufactured by all cement manufacturing companies.

8. Setting Time of Grade-33, Grade-43, Grade-53 Cement

8.1 Standard Test for Setting Time of Cement

1. AASHTO T 131 and ASTM C 191: Time of Setting of Hydraulic Cement
2. AASHTO T 154: Time of Setting of Hydraulic Cement
3. ASTM C 266: Time of Setting of Hydraulic-Cement Paste

9. Frequently Asked Questions (FAQs)

10. Conclusion

Construction industry is progressing at the rapid pace. Bigger, larger, higher structures are putting pressure on cement industry to bring forward high strength cement products. Story started from Grade-33, then Grade-43, and then Grade-53. Higher grades of cement are produced by the industry on demand.

But in parallel, we do also need lower strength cement for lower load carrying members. As Grade-33 is vanishing from the market, engineers need to move towards an new alternative i.e. Portland Pozzolana Cement, etc.

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