What is the permissible fly ash content in PPC?

It must be between 15% and 35% by mass.

What is the 28-day minimum compressive strength for PPC?

33 MPa, which is functionally equivalent to a 33-grade OPC.

What is the minimum initial setting time for PPC?

30 minutes, the same as standard OPC.

Can PPC be used in general RCC works?

Yes, IS 456 explicitly permits the use of PPC in all types of structural reinforced concrete, provided adequate curing is maintained.

IS 1489 Part 1

: 2023

Portland pozzolana cement - Part 1: Fly ash based - Specification

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This standard covers the manufacture, physical, and chemical requirements for fly ash-based Portland pozzolana cement (PPC). It establishes the permissible limits for fly ash addition (15% to 35%) and details the necessary testing criteria to ensure strength, durability, and reduced heat of hydration for construction applications.

Specifies requirements for fly ash based Portland pozzolana cement, promoting use of industrial by-products in construction.

Quick Reference Values

minimum fly ash content15% by mass

maximum fly ash content35% by mass

initial setting timeNot less than 30 minutes

final setting timeNot more than 600 minutes

fineness blaineNot less than 300 m2/kg

compressive strength 3 daysNot less than 16 MPa

compressive strength 7 daysNot less than 22 MPa

compressive strength 28 daysNot less than 33 MPa

Practical Notes

PPC has a lower rate of heat of hydration compared to Ordinary Portland Cement (OPC), making it highly suitable for mass concrete work like dams and thick foundations.

PPC generally requires a slightly longer curing period than OPC to achieve its full strength potential due to the slower, secondary pozzolanic reaction.

PPC provides better resistance against aggressive chemicals (like sulphates and chlorides), making it excellent for marine structures and harsh environments.