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).

IS 14891

: 2000

Specification for Fly Ash for use in Cement Mortar and Concrete

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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 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

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.