Choosing the right type of cement is fundamental to concrete durability and structural performance. India produces over 300 million tonnes of cement annually across numerous types, yet many engineers default to OPC 53 without understanding whether it is actually the best choice for their specific application. This guide covers all major cement types, their IS codes, compositions, and selection criteria.
Classification of Cements
Cements can be classified as:
- Portland Cements: OPC (33, 43, 53 grades)
- Blended Cements: PPC, PSC, Composite Cement
- Special Purpose Cements: SRC, WPC, LHC, RAC, Masonry Cement
Ordinary Portland Cement (OPC) — IS 269:2015
OPC is manufactured by grinding Portland clinker with 3–5% gypsum. It is available in three grades based on 28-day compressive strength:
| Grade | Min 28-day Strength | IS Code | C₃S Content | Primary Use |
|---|---|---|---|---|
| OPC 33 | 33 N/mm² | IS 269 | 45–50% | Masonry, plaster, non-structural |
| OPC 43 | 43 N/mm² | IS 8112 | 50–55% | General RCC, slabs, beams M20–M40 |
| OPC 53 | 53 N/mm² | IS 12269 | 55–65% | High-strength concrete M40+, precast, prestressed |
Key Point: OPC 53 has faster strength gain but higher heat of hydration — avoid for mass concrete pours >1 m thick without thermal management.
Portland Pozzolana Cement (PPC) — IS 1489:2015
PPC is manufactured by intergrinding OPC clinker with 15–35% fly ash (Part 1) or 15–25% calcined clay (Part 2). It is India's most widely used cement today, accounting for ~65% of production.
Advantages over OPC:
- Lower heat of hydration — ideal for mass concrete
- Better long-term strength (strength continues developing up to 90+ days)
- Improved sulphate resistance
- Reduced permeability and better durability
- Lower carbon footprint
Limitations:
- Slower early strength gain (7-day strength lower than OPC)
- Not recommended where formwork must be stripped early
Best for: Mass foundations, dam construction, marine structures, plastering, most residential and commercial RCC work.
Portland Slag Cement (PSC) — IS 455:2015
PSC contains 25–70% Ground Granulated Blast Furnace Slag (GGBS). It offers superior sulphate resistance and is the preferred choice for marine and coastal structures.
| Property | OPC | PPC | PSC |
|---|---|---|---|
| Early strength (7 days) | High | Medium | Low–Medium |
| 28-day strength | High | High | High |
| Heat of hydration | High | Low | Low |
| Sulphate resistance | Low | Medium | Very High |
| Alkali-silica reaction resistance | Low | Medium | High |
| Permeability | Medium | Low | Very Low |
Sulphate Resisting Portland Cement (SRC) — IS 12330:2003
SRC has a very low C₃A content (<5%) making it highly resistant to sulphate attack. Required by IS 456:2000 when sulphate concentration in soil or groundwater exceeds certain limits:
| Class | SO₄ in Soil (g/kg) | SO₄ in Water (g/L) | Cement Required |
|---|---|---|---|
| 1 | <2.0 | <0.3 | OPC/PPC adequate |
| 2 | 2.0–5.0 | 0.3–1.2 | OPC + w/c ≤ 0.50 |
| 3 | 5.0–10.0 | 1.2–2.5 | SRC, w/c ≤ 0.45 |
| 4 | 10.0–20.0 | 2.5–5.0 | SRC, w/c ≤ 0.45 + coatings |
| 5 | >20.0 | >5.0 | SRC + protective barrier |
Low Heat Cement (LHC) — IS 12600:2019
LHC has high C₂S content and low C₃S and C₃A, producing heat of hydration <250 J/g at 7 days. Used in:
- Mass concrete dams
- Large raft foundations
- Bridge piers and abutments
- Any pour where thermal cracking is a risk
Rapid Hardening Cement (RHC) — IS 8041:1990
Achieves 3-day strength equivalent to OPC's 7-day strength. Uses: emergency repairs, cold-weather concreting, precast where rapid demoulding is needed. Higher cost limits general use.
White Portland Cement — IS 8042:1989
Made from limestone and china clay low in iron and manganese. Whiteness index >85. Uses: architectural concrete, mosaic tiles, terrazzo flooring, decorative panels, grout joints.
Composite Cement — IS 16415:2015
Contains clinker + fly ash + GGBS + possibly other pozzolans. Newer category offering flexibility in blending. Gaining popularity for green building projects and LEED-rated structures.
Cement Selection Guide
| Application | Recommended Cement | Reason |
|---|---|---|
| General RCC buildings | PPC or OPC 43 | Cost-effective, good durability |
| High-rise / high-strength | OPC 53 | Fast strength gain, M40+ |
| Marine / coastal | PSC or SRC | Sulphate + chloride resistance |
| Mass concrete (dams, rafts) | LHC or PPC | Low heat of hydration |
| Precast / prestressed | OPC 53 | Fast demoulding strength |
| Sulphate-rich soil | SRC | Sulphate resistance |
| Plastering / masonry | PPC or OPC 33 | Economy, workability |
| Decorative / white finish | White Cement | Appearance |
| Emergency repairs | RHC | Rapid strength |
Storage and Shelf Life
- Store in dry, ventilated godowns on wooden platforms >300 mm above ground
- Stack maximum 10 bags high, use FIFO (First In, First Out)
- Shelf life: 3 months from date of manufacture for OPC; 6 months for PPC/PSC (IS 4082)
- Test cement that has been stored >3 months before use per IS 4031
- Lumped cement = hydrated partially → reject or test
Frequently Asked Questions
Can PPC be used for all RCC work per IS 456:2000?
Yes. IS 456:2000 Clause 5.1 explicitly permits PPC conforming to IS 1489 for all categories of reinforced concrete work. The slower early strength gain must be accounted for in formwork striking times.
Why is OPC 53 not always better than OPC 43?
OPC 53's higher C₃S content increases early strength but also increases heat of hydration and shrinkage. For M20–M35 work, OPC 43 or PPC gives better durability. Use OPC 53 only where early strength is critical or M40+ concrete is required.
What cement is used for RCC in coastal areas of India?
PSC (Portland Slag Cement as per IS 455) is the preferred choice due to its very low chloride permeability and high sulphate resistance. IS 456:2000 Table 3 also mandates M35 minimum with w/c ≤ 0.45 for Very Severe (coastal) exposure.