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There are different grades of cement formed now a day. The First Cement was first discovered in 1824 by Joseph Aspdin. This discovered material was named Portland cement the reason is that the cement was discovered in Portland country so at that time the discovered cement resembled the limestones which were commonly found in Portland country. Later on, the discovered cement was then divided into different grades of Portland cement. The approximate Portland cement composition was.

1. Lime (CaO)                     60 – 70%
2. Silica (SiO2)                    20 – 25%
3. Alumina (Al2O3)            5 – 10%
4. Ferric oxide (Fe2O3)      2 – 3 %

The grades of cement indicate how much cement has a bearing strength. The cement strength (Crushing strength Compressive strength) was generally measured after 28 days with proper curing. Proper curing is very important because curing control the rate of hydration of the cement so proper curing is very important to get the full compressive strength of cement.

## 3 Different grades of cement

Grade 33 Portland cement shows its high workability as compared to the other grades. In mortar for plaster and masonry, grade 33 was commonly used.

Fineness = 300 kg/m^2

Crushing strength 3 days later = 16 N/mm^2

After  7 days later strength = 22 N/mm^2

After 28 days later strength = 33 N/mm^2

GRADE 33 = SHOULD ALWAYS COVER THE SPECIFICATION (IS CODE 269).

Grade 43 Portland cement was generally used in reinforced cement concrete construction which is also called R.C.C. Grade 43 is also used in R.M.C which is also called ready-mix concrete and also use in Pre-cast structure concrete for construction purposes.

Fineness will be = 225 kg/m^2

Crushing strength 3 days later = 23 N/mm^2

After 7 days later strength = 33 N/mm^2

After 28 days later strength = 43 N/mm^2

Grade 43 cement has a good ability to resist sulfate and grade 43 has a low chloride content. The grade 43 cement has good workability and by using this grade we get good and smooth surface output.

GRADE 43 = SHOULD ALWAYS COVER THE SPECIFICATION OF (IS CODE 8112).

In Grade 53 Portland cement the low content of chloride was present and the grade 53 cement has a good ability to resist sulfate. The quantity of the cement is required less in volume because this grade has high strength as compared to the other Portland cement grades.

Grade 53 cement is mainly used in:

1. R.C.C Bridges.
2. Construction of Precast building construction.
3. Construction of factories buildings construction etc. (Strength needed buildings).
4. Concrete sleeper construction (for railways).

The fineness of the grade 53 will be = 225 kg/m^2

Crushing strength 3 days later = 27 N/mm^2

After 7 days later strength = 37 N/mm^2

After 28 days later strength = 53 N/mm^2

THE GRADE 53 = SHOULD ALWAYS COVER THE SPECIFICATION OF (IS CODE 12269).

The grade 53 cement has high strength 28 days later after proper curing. Without proper curing, strength is not properly achieved.

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