Cement was first discovered in 1824 by Joseph Aspdin. This discovered material was named as 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.
- Lime (CaO) 60 – 70%
- Silica (SiO2) 20 – 25%
- Alumina (Al2O3) 5 – 10%
- 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.
Mainly 3 different grades of cement are commonly used which are,
The grade 33 Portland cement shows their high workability as compared to the other grades. In mortar for plaster and for masonry, the 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
The GRADE 33 = SHOULD ALWAYS COVER THE SPECIFICATION (IS CODE 269).
The Grade 43 Portland cement was generally used in reinforced cement concrete construction which also called as R.C.C. The 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
The grade 43 cement is has a good ability to resist sulfate and grade 43 has a low chloride content. The grade 43 cement has a good work ability and by using this grade we get good and smooth surface output.
The 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 we compare to the other Portland cement grades.
Grade 53 cement is mainly used in:
- R.C.C Bridges.
- Construction of Precast building construction.
- Construction of factories buildings construction etc. (Strength needed buildings).
- Concrete sleeper construction (for railways).
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 after 28 days later after proper curing. Without proper curing, the strength is not properly achieved.