What is slag?

What is slag?

• A. A byproduct of steel manufacturing, primarily ground granulated blast-furnace slag (GGBFS) that is used in concrete to enhance strength, reduce heat of hydration, and improve resistance to chemical attacks and cracking.
• B. A brand of cement.
• C. A chemical admixture that accelerates set.
• D. A type of coarse aggregate from limestone.

Answer: (A)

Slag is a byproduct of steel production, and when it is ground into a fine powder called ground granulated blast-furnace slag, it is used in concrete as a supplementary cementitious material. It partially replaces Portland cement, which helps develop long‑term strength, lowers the heat of hydration (reducing thermal cracking in mass concrete), and refines the concrete’s pore structure to improve durability. This combination also enhances resistance to chemical attack and cracking. It isn’t a brand of cement, an additive that accelerates set, or a limestone coarse aggregate, so those options don’t fit the described material and its role in concrete.

Slag is a byproduct of steel production, and when it is ground into a fine powder called ground granulated blast-furnace slag, it is used in concrete as a supplementary cementitious material. It partially replaces Portland cement, which helps develop long‑term strength, lowers the heat of hydration (reducing thermal cracking in mass concrete), and refines the concrete’s pore structure to improve durability. This combination also enhances resistance to chemical attack and cracking. It isn’t a brand of cement, an additive that accelerates set, or a limestone coarse aggregate, so those options don’t fit the described material and its role in concrete.