MATERIALS

Ordinary Portland Cement (OPC)

33/43/53 grade Portland cement. 53 most common for structural use.

Also calledopcopc 33opc 43opc 53ordinary portland cement
Related on InfraLens
CODES
IS 269IS 8112IS 12269
READ
Types of Cement in India — OPC vs PPC vs PSC Guide
Definition

Ordinary Portland Cement (OPC) is the most-widely-used hydraulic cement in Indian construction. Manufactured by grinding clinker (heated limestone + clay + iron-bearing minerals) with gypsum (CaSO4·2H2O) to retard initial setting. Indian Standard IS 269:2015 specifies three OPC grades by 28-day compressive strength: OPC 33 (33 MPa min), OPC 43 (43 MPa min), OPC 53 (53 MPa min). Higher grades have finer grinding (more surface area = faster hydration) and tighter chemistry control on tricalcium silicate (C3S) and tricalcium aluminate (C3A) content.

Major Indian OPC manufacturers: Ultratech (Aditya Birla), ACC, Ambuja, Shree Cement, Dalmia, Ramco, JK Cement, India Cements. The market is competitive; OPC 53 grade dominates ready-mix concrete applications above M25; OPC 43 grade is common for general residential construction and concrete blocks. OPC 33 grade is now rarely produced due to obsolescence — most BIS-licensed mills produce only 43 and 53 grades. The shift from OPC to PPC (Portland Pozzolana) in the past 20 years has been driven by cost (PPC uses 25-30% fly ash, reducing clinker cost) and durability advantages in marine / aggressive environments.

Properties of fresh OPC: fine grey powder, density 3.15 g/cc, bulk density 1440 kg/m³, fineness 250-350 m²/kg (Blaine surface area), initial setting time 30 minutes minimum, final setting time 600 minutes maximum, soundness ≤ 10 mm (Le Chatelier expansion). Hardened OPC: density of fully-hydrated paste 2.0-2.4 g/cc; compressive strength as specified by grade; tensile strength ~10-12% of compressive; elastic modulus 30-35 GPa. Storage: limit shelf life to 3 months from manufacture per IS 269; older cement can have 20-40% strength loss due to absorbed atmospheric moisture (false setting). Site engineers should check the manufacturer's date on every cement consignment and reject expired bags.

Typical values
OPC 33 — 28-day strength33 MPa min
OPC 43 — 28-day strength43 MPa min
OPC 53 — 28-day strength53 MPa min
OPC density (powder)1440 kg/m³ bulk
Initial setting time30 min minimum
Final setting time600 min (10 hours) maximum
Fineness (Blaine surface area)250-350 m²/kg
Where used
  • Reinforced concrete (RCC) for residential, commercial, infrastructure
  • Pre-stressed concrete (PSC) — typically OPC 53 minimum for fast strength gain
  • Precast concrete elements — sleepers, beams, panels (OPC 53 for early strength)
  • Masonry mortar and plaster (OPC 43 typical)
  • Speciality applications — high-strength concrete (M40+) requires OPC 53
Acceptance / threshold
Per IS 269:2015: chemical composition (LSF, SM, A/F ratio), physical properties (fineness, setting time, soundness, compressive strength) per Tables 2-3. Mill test certificate (MTC) with each consignment; sample-test 1 in 50 t for important works.
Site example
Site reality: a Pune commercial project's OPC 53 consignment from a non-major mill tested at 41.5 MPa at 28 days — below the 53 MPa specified. The mill's batch had been ground too coarsely (Blaine 245 m²/kg vs 280-310 typical for OPC 53). Replacement consignment from Ultratech testing at 56 MPa was specified for the rest of the project. Always verify cement grade against actual test certificate; mill brand name alone is not sufficient.
Frequently asked
What is OPC and how is it different from PPC?
Ordinary Portland Cement (OPC) is pure cement clinker + gypsum, with no mineral admixtures. Portland Pozzolana Cement (PPC) is OPC + 15-35% fly ash or other pozzolanic material per IS 1489. OPC has faster early strength gain; PPC has slower early but better long-term strength and durability. PPC is now dominant in Indian RMC for cost (cheaper) and durability (better against marine / aggressive environments) reasons.
Which is better — OPC 43 or OPC 53?
Depends on application. OPC 53 has higher early strength (faster shuttering removal, faster construction cycle) and is suitable for high-strength concrete (M40+). OPC 43 is adequate for general residential and commercial construction (M20-M30). OPC 53 is more sensitive to over-dosing of admixtures and may show false setting if old. For typical residential M25 construction, OPC 43 is more economical and suitable. For pre-stressed and precast, OPC 53 minimum.
What is shelf life of cement?
Per IS 269, cement should be used within 3 months of manufacture. Older cement absorbs atmospheric moisture (forming partially-hydrated calcium silicates) which causes 'false setting' — apparent stiffening that can be re-dispersed by re-mixing but with reduced final strength. Typical strength loss: 20% at 6 months, 40-50% at 1 year. Site QC must check the manufacturing date on every bag and reject any with date older than 3 months for important structural work.
Related materials terms
Portland Pozzolana Cement (PPC)
Cement blended with fly ash. More durable than OPC.
Portland Slag Cement (PSC)
Cement blended with blast furnace slag
Aggregates (Fine & Coarse)
Coarse (10-40mm) and fine (sand) aggregates per IS 383
Sand (River / M-Sand)
Fine aggregate. River sand or manufactured sand.
Brick / Block Masonry
Bricks per IS 1077, blocks per IS 2185
Tile (Floor / Wall / Roof)
Floor/wall/roof tiles per various IS codes
Paint & Coatings
Wall paint, primer, putty, coatings
Marine Plywood (BWP)
Boiling water proof plywood for marine and exterior use per IS 710