Cement Chemistry Topic - 5 Somewhere on an Indian construction site today, a specification says "cement as per IS 456." The contractor reads that as permission to use the cheapest available cement. The engineer who wrote it intended something far more specific.

That gap is where many durability problems begin.
Cement isn't a commodity where brand is the only variable.
OPC, PPC, PSC, and SRC are fundamentally different materials with different hydration behaviour, heat generation, durability, and ideal applications.
Specifying only "cement" is a durability decision made by omission.

𝐎𝐏𝐂 (𝐎𝐫𝐝𝐢𝐧𝐚𝐫𝐲 𝐏𝐨𝐫𝐭𝐥𝐚𝐧𝐝 𝐂𝐞𝐦𝐞𝐧𝐭)
• High early strength and high heat of hydration.
• Best for precast, rapid formwork removal, and cold-weather concreting.
• Not ideal for mass concrete or aggressive exposure conditions.

𝐏𝐏𝐂 (𝐏𝐨𝐫𝐭𝐥𝐚𝐧𝐝 𝐏𝐨𝐳𝐳𝐨𝐥𝐚𝐧𝐚 𝐂𝐞𝐦𝐞𝐧𝐭)
• Fly ash blended cement with lower heat and better long-term durability.
• Ideal for mass concrete, infrastructure, hydraulic works, and hot-weather concreting.
• Widely used in India, but fly ash content and quality can vary significantly between manufacturers.

𝐏𝐒𝐂 (𝐏𝐨𝐫𝐭𝐥𝐚𝐧𝐝 𝐒𝐥𝐚𝐠 𝐂𝐞𝐦𝐞𝐧𝐭)
• GGBS blended cement with low heat, low permeability, and excellent resistance to chloride and sulfate attack.
• Well suited for marine structures, coastal infrastructure, foundations, and water-retaining structures.
• Technically underutilised despite its durability advantages.

𝐒𝐑𝐂 (𝐒𝐮𝐥𝐟𝐚𝐭𝐞-𝐑𝐞𝐬𝐢𝐬𝐭𝐢𝐧𝐠 𝐂𝐞𝐦𝐞𝐧𝐭)
• Low C3A content to resist sulfate attack.
• Intended for sulfate-bearing soils, sewage, and industrial environments.
• Essential where sulfates exist, unnecessary where they don't.

The takeaway:
Every concrete element has an exposure condition. Every exposure condition deserves an appropriate cement type.
That decision should be made during design, not left to procurement.

Author - Buildonomics Research Team