Different grades of Ordinary Portland cement
Ordinary Portland Cement(OPC) is extensively utilized in the construction sectors as primary component for developing concrete, mortar, stucco, and non-specialty grouts. Ordinary Portland Cement is graded on the basis of its strength. The grade specifies the compressive strength of the mortar cube that will be achieved once 28 days of setting is completed.
Grades of Ordinary Portland Cement - The following grades of OPC are available:
1. OPC 33 Grade Cement: This grade of cement is suited for general construction under normal ecological condition.
Compressive Strength of OPC 33 – The average compressive strength of minimum three mortar cubes with a face area of 50 sq.cm is considered at the time of verifying the compressive strength. These mortar cubes comprise of one part of cement and three parts of standard sand.
Compressive Strength of OPC 33:
a) 72 +/- 1 hour = Not under 16 N/mm2
b) 168 +/- 2 hours = Not under 22 N/mm2
c) 672 +/- 4 hours = Not under 33 N/mm2
IS Code – IS 269 : 1989 for Ordinary Portland Cement, 33 Grade.
2. OPC 43 Grade Cement: Now-a-days, this grade of cement is gaining popularity in the construction sectors. OPC 43 is suitable for general RCC construction where the grade of concrete is up to M30. It can also be applied for the construction of various precast items like blocks, tiles, asbestos products like sheets and pipes, and for non-structural works like plastering, flooring etc.
Compressive Strength of OPC 43:
a) 72 +/- 1 hour = Not under 23 N/mm2
b) 168 +/- 2 hours = Not under 33 N/mm2
c) 672 +/- 4 hours = Not under 43 N/mm2
IS Code – IS 8112: 1989 for 43 Grade Ordinary Portland Cement.
3. OPC 53 Grade Cement: OPC 53 is useful while requiring concrete with greater strength at very reasonable cement content. OPC 53 facilitates 8 to 10% saving of cement in concrete mix design, for concrete M20 and over.
This cement grade is very effective for specialized works like pre-stressed concrete components, several precast items like paving blocks, building blocks etc, runways, concrete roads, bridges, and other RCC works where the grade of concrete remains M25 and over.
Compressive Strength of OPC 53:
a) 72 +/- 1 hour = Not under 27 N/mm2
b) 168 +/- 2 hours = Not under 37 N/mm2
c) 672 +/- 4 hours = Not under 53 N/mm2
IS Code – IS 12269 : 1987 for Specification for 53 grade ordinary portland cement.