Cement is an essential component of concrete, and its strength is directly proportionate to the strength of the concrete. Ordinary Portland Cement (OPC) is available in three grades: 33 grade cement, 43 grade cement, and 53 grade cement. According to the Bureau of Indian Standards, these classes are distinguished by their compressive strengths, measured in megapascals (Mpa), or N/mm2.
The compressive strength of cement evaluated after 28 days is used to classify these cement grades. Cement is an essential component of concrete, and its strength is directly proportionate to the strength of the concrete. In this article, we will discuss the difference between 33 grade, 43 grade, and 53 grade cement.
Difference Between 33 Grade, 43 Grade, And 53 Grade Cement
33 Grade Cement
Under normal environmental conditions, this grade of cement is used for general construction. However, the low compressive strength of OPC grade 33 and the availability of higher grades of cement has had an impact on its use and demand.
43 Grade Cement
OPC 43 grade cement is mainly used in a typical RCC building where the concrete grade is up to M30. It is also utilized in the manufacture of precast items such as blocks and tiles, asbestos products such as sheets and pipes, and non-structural work such as plastering and flooring.
53 Grade Cement
When we need stronger strength concrete with a low cement content, we utilize OPC 53. This cement grade is employed in specialized works like prestressed concrete components, precast items like paving blocks and construction blocks, runways, concrete roadways, bridges, and other RCC works where the concrete grade is M25 or above.
2. IS Codes
- IS 12269 is the standard for 53 grade cement.
- IS 8112 is used for 43 grade cement.
- IS 269 is used in 33 grade cement.
3. Compressive Strength
The following approach is used to compute compressive strength:
- In proportion, water and sand are added to the cement.
- To create homogeneous concrete, appropriate mixing must be assured.
- Which is then poured into formwork and hardened.
- Cubes are evaluated in the lab at three-day, seven-day, and 28-day intervals.
- Testing demonstrates the strength attained by cement throughout that time frame.
The table below shows the strength of all three grades of cement at three-day, seven-day, and 28-day intervals.
|Sr.No.||Grade of cement||Compressive Strength in 3 days (N/mm2)||Compressive Strength in 7 days (N/mm2)||Compressive Strength in 28 days (N/mm2)|
As can be seen, the initial strength of cement 53 is greater than that of 33 grade and 43.
Because of the initial strength rise, the strength of grade 53 cement does not improve considerably after 28 days, whereas grade 33 and 43 cement continues to acquire strength after 28 days.
33 and 43-grade cement will eventually reach their respective maximum strength as that of 53-grade cement.
4. Heat of Hydration
When water is added to cement, it reacts with the compounds in the cement, producing heat. This is known as the heat of hydration. During the initial stage of curing, the tremendous heat of hydration can cause microscopic cracks in concrete.
As a result, the likelihood of microcracks is substantially higher; these microcracks may not be evident on the surface. The amount of cement in the mix is routinely increased by site supervisors or masons. They believe this will improve the concrete’s strength and durability. However, it causes microcracks in the concrete.
When compared to OPC 33 and OPC 43 cement grades, OPC 53 grade cement produces higher heat of hydration. As a result, 53 grade cement should be used only where such applications justify the production of stronger concrete, where there is good monitoring and quality verification, and where necessary safeguards are taken to limit the greatest heat of hydration through an appropriate healing process.
The medium heat of hydration is released by the 43-grade cement. The hydration heat of 33-grade cement is minimal.
- The cost of 33 grade cement is less than that of 43 grade cement.
- The cost of 43 grade cement is higher than that of 33 but cheaper than that of 53 grade cement.
- The cost of 53 grade cement is greater than the prices of cement 33 and 43 grade cement.
6. Initial And Final Setting Time
When tested by the Vicat’s apparatus by the method described in IS 4931 (Part 5): 1988, the setting time of cement states that the initial setting time should not be less than 30 minutes and the final setting time should not be more than 600 minutes.
The initial and final setting time of all three grades of OPC, i.e., 33 grade cement, 43 grade cement, and 53 grade cement, is the same.
7. Fineness Of Cement
Fineness, when determined by using Blaine’s air permeability method, as stated in IS 4031 (Part 2):1988, should be 225 m2/kg for all three OPC 33, 43, and 53 grade cement.
8. Soundness Of Cement
Unaerated cement should not exhibit an expansion of more than 10 mm and 0.8 percent for all three grades of OPC when tested using the ‘Le Chatelier’ method and autoclave test defined in IS 4031 (Part 3): 1988.
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