IS 1489:2015 Part 2 is the Indian Standard (BIS) for portland-pozzolana cement - specification - part 2: calcined clay based. This standard specifies the requirements for the manufacture, chemical and physical properties, and testing of Portland-Pozzolana Cement (PPC) incorporating calcined clay. It is extensively used in mass concrete, marine, and hydraulic structures due to its low heat of hydration and improved resistance to chemical attacks.
Specifies requirements for portland-pozzolana cement (PPC) manufactured using calcined clay as pozzolanic material.
Calcined-clay-blended PPC composition, strength, fineness and durability properties.
| Reference | Value | Clause |
|---|---|---|
| Calcined clay content (range, by mass) | 10 – 25 % | Cl. 5.1 |
| 28-day compressive strength (min) | 33 MPa | Cl. 6.2 (Table 4) |
| 7-day compressive strength (min) | 22 MPa | Cl. 6.2 (Table 4) |
| 3-day compressive strength (min) | 16 MPa | Cl. 6.2 (Table 4) |
| Fineness — Blaine (min) | 300 m²/kg | Cl. 6.1.1 |
| Soundness — Le Chatelier (max) | 10 mm | Cl. 6.1.2 |
| Soundness — autoclave (max) | 0.8 % | Cl. 6.1.2 |
| Initial setting time (min) | 30 minutes | Cl. 6.1.3 |
| Final setting time (max) | 600 minutes | Cl. 6.1.3 |
| Drying shrinkage (max) | 0.15 % | Cl. 6.1.4 |
| MgO (max) | 6.0 % | Cl. 5.2 (Table 1) |
| SO₃ (max) | 3.0 % | Cl. 5.2 (Table 1) |
| Loss on ignition (max) | 5.0 % | Cl. 5.2 (Table 1) |
| Insoluble residue (max) | Calcined clay × % + 4 % (formula) | Cl. 5.2 (Table 1) |
| Pozzolanic activity index (min) | 75 % at 28 days (vs OPC control) | |
| Total chloride (max) | 0.05 % | Cl. 5.2 (Table 1) |
| Sulphate resistance | Improved vs plain OPC | |
| Heat of hydration | Lower than OPC (typical reduction ~15 %) | |
| Standard bag mass | 50 kg ± 2 % | Cl. 9.1 |
IS 1489 (Part 2) specifies Portland-Pozzolana Cement (PPC) — Calcined Clay based — the variant of PPC that uses calcined clay as the pozzolan instead of fly ash (covered by IS 1489 Part 1). It is a relatively new product in Indian markets, gaining traction as a sustainability-driven alternative to OPC (lower clinker factor, lower carbon footprint) and to fly-ash PPC (alternative pozzolan source).
Use IS 1489 Part 2 calcined-clay PPC when: - Specific projects require certified low-carbon cement - Fly ash supply is unreliable or geographically far - Calcined clay (metakaolin or thermally activated clay) is locally available - Long-term durability is critical (calcined clay has good chloride resistance) - High-strength concrete with sustainability credentials (LC3 — Limestone Calcined Clay Cement variants) - Projects targeting GRIHA / IGBC / LEED certification
IS 1489 Part 2 is the BIS specification for the calcined-clay PPC product. Closely related international concept: LC3 (Limestone Calcined Clay Cement) — research-backed cement with up to 50 % clinker replacement using a blend of limestone + calcined clay. LC3 has been piloted in India by IIT Madras and Holcim; commercial availability growing.
Composition (Clause 5): - Clinker (Portland cement clinker): 65-85 % - Calcined clay pozzolan: 15-35 % - Gypsum: 3-7 % (set regulator) - Total: 100 %
Lower clinker factor than OPC = lower CO₂ per tonne of cement (one of the key sustainability metrics).
Mechanical strength (Clause 7, mortar cubes 1:3 with standard sand at w/c 0.4): - 7-day: ≥ 22 MPa - 28-day: ≥ 33 MPa (similar to 33-grade OPC) - 90-day: typically 38-45 MPa (long-term gain due to pozzolanic reaction)
Note: 28-day strength is similar to OPC 33; long-term strength gain is a feature.
Chemical limits (Clause 6): - LOI (Loss on Ignition): ≤ 5.0 % - MgO: ≤ 6.0 % - SO₃: ≤ 3.0 % - Cl⁻: ≤ 0.10 % - Insoluble residue: per Annex (depends on calcined clay content)
Physical properties: - Fineness (Blaine): ≥ 300 m²/kg (typically 320-380 m²/kg) - Setting time: - Initial: ≥ 30 min - Final: ≤ 600 min - Soundness: - Le Chatelier expansion: ≤ 10 mm - Autoclave expansion: ≤ 0.8 %
Calcined clay quality requirements (Annex): - Pozzolanic activity index ≥ 75 % at 7 days; ≥ 85 % at 28 days - Particle size: ~10-20 µm typical (similar fineness to cement) - Calcination temperature: 600-800 °C (turns clay minerals into reactive amorphous form)
Strength comparison (28-day mortar cube):
| Cement | 28-d MPa | |---|---| | OPC 53 (IS 12269) | ≥ 53 | | OPC 43 (IS 8112) | ≥ 43 | | OPC 33 / IS 269 33-grade | ≥ 33 | | PPC fly-ash (IS 1489 Part 1) | ≥ 33 | | PPC calcined clay (this code, IS 1489 Part 2) | ≥ 33 | | PSC (IS 455) | ≥ 33 |
Carbon footprint (per tonne of cement): - OPC: 850-900 kg CO₂ - PPC fly-ash: 600-700 kg CO₂ - PPC calcined clay: 550-700 kg CO₂ - LC3 variant: 450-600 kg CO₂ - Plain calcined clay (no clinker — non-cementitious): 300-400 kg CO₂
Concrete mix design implications (vs OPC): - Slightly higher water demand for given workability - Initial set + early-age strength similar; 28-day similar; 90-day gain greater - Hydration heat lower (good for mass concrete) - Chloride resistance better (good for marine, parking, basement) - Sulphate resistance moderate (better than OPC, weaker than SRC)
1. Treating PPC calcined-clay as identical to OPC for mix design. Different early-age vs long-term strength curve; trial mix essential. 2. Inadequate trial mix verification. PPC calcined-clay has less long-term R&D in India than fly-ash PPC; do trial mix per project. 3. Specifying only 28-day strength target. PPC calcined-clay's value is in long-term (90-day) gain; specify 28-day + 90-day strength targets. 4. No supplier qualification audit. Calcined clay quality varies; demand pozzolanic activity test certificate. 5. Mixing different pozzolan-cement types in same pour. Different setting times + workability; create joints + cracks. One cement type per pour. 6. Storing calcined-clay PPC longer than recommended. Hygroscopic — absorbs moisture, lump formation. Use within 3 months of delivery. 7. Lower water-cement ratio assumption from OPC carries to PPC. PPC needs slightly more water for similar workability; verify by trial. 8. Curing inadequate for PPC. Pozzolanic reaction continues for weeks; without good curing, potential strength gain is lost. Extended curing (14-28 days) recommended. 9. Ignoring chloride / sulphate resistance benefits. PPC calcined-clay is durable; designer can leverage for cost savings (less cement cover, etc., per IS 456). 10. No consideration of supplier reliability. Calcined-clay PPC supply still maturing in India; have backup supplier qualified. 11. Carbon footprint claim without third-party verification. For green building certification (GRIHA / IGBC / LEED), need EPD (Environmental Product Declaration); demand from supplier. 12. Trial mix only at 28 days. Verify long-term performance at 90 days for PPC; gives true picture of cement type's value.
Sustainable cement options in India (2026 landscape):
1. OPC (53 / 43 / 33 grade) — Workhorse; high strength, fast turnaround, well-known properties; highest carbon footprint per tonne. 2. PPC (fly ash, IS 1489 Part 1:2015) — Most common alternative; uses fly ash from coal-fired power plants; lower carbon, similar 28-day strength to OPC 33; abundant supply. 3. PPC (calcined clay, this code, IS 1489 Part 2:2015) — Newer; uses calcined clay; alternative to fly ash for projects where fly ash is unreliable; sustainability angle. 4. PSC (Portland Slag Cement, IS 455:2015) — Uses GGBS from steel industry; low heat, good for mass concrete; supply linked to steel industry geography. 5. SRC (Sulphate-Resisting Cement, IS 12330:1988) — For aggressive sulphate exposure (marine, sulphate-rich soil). 6. Composite cements (multi-pozzolan) — Blends of multiple supplementary cementitious materials. 7. LC3 (Limestone Calcined Clay Cement) — Research-backed; up to 50 % clinker replacement; pilot-scale commercial. 8. Geopolymer cement — No Portland clinker at all; alkali-activated fly ash / slag; experimental at large scale.
Selection cascade:
For green building rating projects: - GRIHA: blended cements get points - IGBC: blended cements get points; carbon footprint reduction quantified - LEED: regional materials + low-carbon cement get credits
Cost (typical, 2026): - OPC 43: ₹400-450 per bag (50 kg) - PPC fly-ash: ₹390-440 per bag - PPC calcined-clay: ₹420-470 per bag (less commonly available; price premium) - PSC: ₹400-450 per bag
IS 1489 Part 2 is one piece of the broader sustainability shift in Indian cement industry. As LC3 + green-cement awareness grows, this product line will gain market share.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Fly Ash Content by Mass | 15% to 35% | Up to 40% (for Type IP) | ASTM C595/C595M-21 |
| 28-day Compressive Strength (min) | 33.0 MPa | 28.0 MPa (for Type IP) | ASTM C595/C595M-21 |
| 7-day Compressive Strength (min) | 22.0 MPa | 17.0 MPa (for Type IP) | ASTM C595/C595M-21 |
| Fineness (Blaine's Air Permeability) | ≥ 320 m²/kg | No limit specified for Type IP (performance-based) | ASTM C595/C595M-21 |
| Soundness (Autoclave Expansion, max) | 0.8% | 0.8% | ASTM C595/C595M-21 |
| Initial Setting Time (min) | ≥ 30 minutes | ≥ 45 minutes | ASTM C595/C595M-21 |
| Final Setting Time (max) | ≤ 600 minutes | ≤ 420 minutes | ASTM C595/C595M-21 |
| Drying Shrinkage (max) | 0.15% | 0.06% at 28 days (optional requirement) | ASTM C595/C595M-21 |