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IS 14891:2000 is the Indian Standard (BIS) for fly ash for use in cement mortar and concrete. This standard specifies the requirements for manufacturing, chemical composition, and physical properties of Portland Pozzolana Cement (PPC) using fly ash as the pozzolanic material. It is a blended cement known for enhanced durability, resistance to chemical attack, and lower heat of hydration, making it suitable for a wide range of construction applications.
Specifies requirements for fly ash for use as an admixture in cement mortar and concrete.
Quick Reference — IS 14891:2000 Fly Ash for Mortar/Concrete
Specification for fly ash for use in cement mortar and concrete (separately from PPC manufacture).
✓ Verified 2026-04-28
Reference
Value
Clause
Fly ash type — Class F (siliceous)
low-CaO, from anthracite/bituminous coal
Cl. 3 (Table 1)
Fly ash type — Class C (calcareous)
high-CaO, from sub-bituminous/lignite
Cl. 3 (Table 1)
SiO₂ + Al₂O₃ + Fe₂O₃ — Class F
≥ 70 %
Cl. 4 (Table 2)
SiO₂ + Al₂O₃ + Fe₂O₃ — Class C
≥ 50 %
Cl. 4 (Table 2)
SO₃ — maximum
5.0 % (Class F), 5.0 % (Class C)
Cl. 4 (Table 2)
Loss on ignition — Class F
≤ 5 %
Cl. 4 (Table 2)
Loss on ignition — Class C
≤ 5 %
Cl. 4 (Table 2)
Moisture content — maximum
3 %
Cl. 4 (Table 2)
Available alkalis (Na₂O eq.) — max
1.5 %
Cl. 4 (Table 2)
Fineness — passing 45 μm sieve
≥ 66 %
Cl. 5 (Table 3)
Strength activity index — 7 days
≥ 75 %
Cl. 5 (Table 3)
Strength activity index — 28 days
≥ 75 %
Cl. 5 (Table 3)
Soundness — autoclave expansion
≤ 0.8 %
Cl. 5 (Table 3)
Density (specific gravity)
2.0–2.6
(typical)
Replacement of cement — typical RMC
20–35 % by mass
(IS 456 Cl. 5.2)
Replacement of cement — high-volume FA
50–60 %
(specialty mass concrete)
Storage — moisture protection
covered silo / sealed bags
Cl. 7
Effect on early strength (vs OPC)
−15 to −25 % at 7 days
(typical)
Effect on 56-day strength
+10 to +15 % vs OPC
(typical)
Effect on heat of hydration
−25 to −40 % vs OPC
(typical)
⚠ Distinct from IS 3812 (fly ash as Pozzolana, including for PPC manufacture). IS 14891 covers post-mix addition. Reaffirmed.
Overview
Status
Current
Usage level
Essential
Domain
Materials Science — Demolition, Renovation and Repair of Structures
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! PPC generally exhibits slower early strength gain compared to OPC. Ensure adequate curing, typically for a minimum of 10 days, to achieve desired long-term strength.
! Due to its lower heat of hydration, fly ash-based PPC is ideal for mass concrete works like rafts, dams, and large foundations to minimize thermal cracking.
! The finer particles of PPC lead to denser, less permeable concrete, providing better protection against reinforcement corrosion and chemical attacks in aggressive environments.
Standard Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete
Specifies chemical and physical requirements for fly ash used as a mineral admixture in concrete.
EN 450-1:2012CEN (European Committee for Standardization)
HighCurrent
Fly ash for concrete - Part 1: Definition, specifications and conformity criteria
Defines specifications and conformity criteria for siliceous fly ash for use in concrete production.
AS/NZS 3582.1:2016Standards Australia / Standards New Zealand
HighCurrent
Supplementary cementitious materials, Part 1: Fly ash
Specifies requirements for fly ash as a supplementary material for use in cement, mortar, and concrete.
CSA A3001-18CSA Group (Canada)
MediumCurrent
Cementitious materials for use in concrete
Covers multiple cementitious materials, including fly ash (Types F, CI, CH), for use in concrete.
Key Differences
≠Classification System: The Indian standard IS 3812 (which covers this scope) uses Grade 1 and Grade 2, primarily based on fineness. In contrast, the most common international equivalent, ASTM C618, classifies fly ash as Class F (low calcium) or Class C (high calcium), based on the chemical composition and source coal.
≠Pozzolanic Activity Test: IS 3812 specifies a unique 'Lime Reactivity' test (minimum 4.5 MPa) where fly ash is mixed with hydrated lime. ASTM C618 uses a 'Strength Activity Index' with Portland cement, requiring the fly ash-cement mortar to achieve at least 75% of the strength of a control mortar.
≠Fineness Specification: While both IS and ASTM specify a maximum retention on a 45-micron sieve, IS 3812 (Grade 1) adds a mandatory minimum specific surface area (320 m²/kg by Blaine's method), which is not required by ASTM C618.
≠Calcium Oxide (CaO) Content: ASTM C618 implicitly differentiates classes by CaO content (Class C typically has >10% CaO), which imparts self-cementing properties. IS 3812 does not have a direct classification based on CaO, and its requirement for min. 70% (SiO₂+Al₂O₃+Fe₂O₃) effectively limits most Indian fly ash to be low-calcium, similar to ASTM Class F.
Key Similarities
≈Sum of Oxides Requirement: Both IS 3812 and ASTM C618 (for Class F) mandate a minimum of 70% for the sum of the primary pozzolanic components (SiO₂ + Al₂O₃ + Fe₂O₃), ensuring the material is predominantly glassy aluminosilicate.
≈Loss on Ignition (LOI) Limit: Both standards impose a strict limit on LOI to control the unburnt carbon content, which can negatively affect water demand and air entrainment. The limits are very similar (IS 3812: ≤5.0%; EN 450-1: ≤5.0%; ASTM C618: ≤6.0%).
≈Soundness Test: Both IS 3812 and ASTM C618 specify a maximum autoclave expansion of 0.8% to ensure the volumetric stability of the concrete and prevent long-term deleterious expansion due to excessive free lime or magnesia.
≈Sulphate Content Limit: All major standards limit the Sulphur Trioxide (SO₃) content to mitigate the risk of internal sulphate attack and durability issues like delayed ettringite formation in the hardened concrete.
Parameter Comparison
Parameter
IS Value
International
Source
Sum of Oxides (SiO₂+Al₂O₃+Fe₂O₃), min
70.0% (for IS 3812)
70.0% (Class F)
ASTM C618-22a
Loss on Ignition (LOI), max
5.0% (for IS 3812)
5.0% (Category A)
EN 450-1:2012
Fineness (retained on 45 μm sieve), max
34% (Grade 1, for IS 3812)
34%
ASTM C618-22a
Specific Surface (Blaine), min
320 m²/kg (Grade 1, for IS 3812)
Not Specified
ASTM C618-22a
Sulphur Trioxide (SO₃), max
3.0% (for IS 3812)
5.0%
ASTM C618-22a
Soundness (Autoclave Expansion), max
0.8% (for IS 3812)
0.8%
ASTM C618-22a
Strength Activity Index with cement (28 days)
≥ 80% of control strength (for IS 3812)
≥ 75% of control strength
ASTM C618-22a
⚠ Verify details from original standards before use
Key Values8
Quick Reference Values
Fly Ash Content15% to 35% by mass
Minimum 3-Day Compressive Strength16 MPa
Minimum 7-Day Compressive Strength22 MPa
Minimum 28-Day Compressive Strength33 MPa
Minimum Initial Setting Time30 minutes
Maximum Final Setting Time600 minutes
Maximum Loss on Ignition5.0 %
Minimum Fineness (Specific Surface)300 m²/kg
Tables & Referenced Sections
Key Tables
Table 2 - Chemical Requirements for Portland Pozzolana Cement, Fly Ash Based
Table 3 - Physical Requirements for Portland Pozzolana Cement, Fly Ash Based
Key Clauses
Clause 4 - Raw Materials
Clause 6 - Chemical Requirements
Clause 7 - Physical Requirements
Clause 10 - Storage
Clause 11 - Manufacturer’s Certificate and Marking
What is the allowed percentage of fly ash in PPC?+
The fly ash content must be between 15% and 35% by mass of the cement, as per Clause 4.2.1.
What is the minimum required compressive strength for PPC at 28 days?+
The minimum 28-day compressive strength must be 33 MPa (N/mm²), as specified in Table 3.
What is the minimum fineness for fly ash based PPC?+
The minimum fineness (specific surface) is 300 m²/kg when tested by the Blaine's air permeability method, as per Table 3.
Is PPC suitable for marine construction?+
Yes, PPC is highly recommended for marine structures due to its high resistance to chloride and sulphate attacks, leading to more durable concrete (Annex F).