Ordinary Portland Cement (OPC)
ordinary portland cement opc
🧱 Ordinary Portland Cement (OPC) — Full Definition
Ordinary Portland Cement (OPC) is the most common and widely used type of cement in the construction industry. It is a hydraulic cement, meaning it sets and hardens when mixed with water due to chemical reactions (hydration).
OPC is primarily composed of clinker (a mixture of calcium silicates produced from limestone and clay) and a small amount of gypsum (to control the setting time).
🔹 Main Components
| Component | Typical Percentage | Function |
|---|---|---|
| Clinker (CaO·SiO₂, CaO·Al₂O₃, CaO·Fe₂O₃) | 90–95% | Provides strength through hydration |
| Gypsum (CaSO₄·2H₂O) | 3–5% | Controls setting time |
🔹 Chemical Composition (Approx.)
| Compound | Symbol | Typical Range (%) |
|---|---|---|
| Tricalcium Silicate | C₃S | 45–60 |
| Dicalcium Silicate | C₂S | 15–30 |
| Tricalcium Aluminate | C₃A | 6–12 |
| Tetracalcium Aluminoferrite | C₄AF | 6–10 |
🔹 Physical Properties
| Property | Typical Value |
|---|---|
| Specific Gravity | 3.10 – 3.15 |
| Fineness (Blaine) | 280–320 m²/kg |
| Initial Setting Time | ≥ 30 minutes |
| Final Setting Time | ≤ 600 minutes |
| Compressive Strength (28 days) | 42.5–62.5 MPa depending on grade |
🔹 Available Grades (per ASTM & EN Standards)
OPC 32.5 N/R – for general concrete and plastering.
OPC 42.5 N/R – for reinforced concrete structures.
OPC 52.5 N/R – for high-strength and industrial structures.
🔹 Applications
Building foundations, beams, slabs, columns.
Bridges, tunnels, and dams.
Precast concrete products.
Roads and runways.
🔹 Advantages
High early and ultimate strength.
Excellent bonding with aggregates.
Suitable for all general-purpose concrete work.
Readily available and economical.
🔹 Packaging for Export
| Form | Common Sizes |
|---|---|
| Bags | 25 kg / 50 kg |
| Bulk | 1–1.5 MT jumbo bags or bulk vessel shipments |
🔹 Storage Conditions
Store in a dry, moisture-free area on raised wooden pallets, covered with waterproof sheeting, to prevent lump formation and loss of strength.
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