| Standard Number |
IS: 269–1950 |
| Title |
Indian Standard Specification for Ordinary Portland Cement (OPC) |
| Applicable Grade |
33 Grade OPC (as per earlier classification) |
| Purpose |
To define the quality, composition, and testing requirements of Ordinary Portland Cement. |
| Physical Requirements |
- Fineness (Blaine) – Not less than 225 m²/kg
- Soundness (Le Chatelier) – Not more than 10 mm
- Initial Setting Time – Not less than 30 minutes
- Final Setting Time – Not more than 600 minutes
- Compressive Strength:
- 3 Days – ≥ 16 MPa
- 7 Days – ≥ 22 MPa
- 28 Days – ≥ 33 MPa
|
| Chemical Requirements |
- Lime Saturation Factor (LSF): 0.66–1.02
- Insoluble Residue – ≤ 4%
- Magnesia (MgO) – ≤ 6%
- SO₃ (Sulphur trioxide) – ≤ 2.5% (when C3A ≤ 5%)
- Loss on Ignition – ≤ 5%
|
| Marking |
Each bag should be marked with ISI certification, batch number, date of manufacture, and net mass. |
| Reference Clause |
B2 12 – Covers details about packaging, sampling, and storage conditions |
| Application |
General construction work (buildings, pavements, RCC structures) |
