Steel slag can be the material for which of the following? Select the correct answer using the code given below:

Answer: (d) 1, 2 and 3

Roads, acidic-soil improvement and cement all use slag.

Statement by statement

1. ✓ YES Processed steel slag replaces natural aggregate in road bases (CRRI trials, 2022 Surat road).

2. ✓ YES Its lime content neutralises acidic soils and adds nutrients.

3. ✓ YES Blast-furnace and steel slag are used to make cement.

The idea

In a steel furnace, limestone is added to pull impurities out of the molten iron. The impurities and lime float on top as slag. So slag is rich in lime and silicates, much like the raw material of cement and like the lime farmers put on acid soil. That explains all three uses.

Hard and stony when cooled → crushed for road base → Rich in lime → corrects acidic soil → Lime and silicates → raw material for cement

The trap

Using waste on farms sounds risky, but slag works like agricultural lime.

Also know

India is the second-largest steel producer, and each tonne of steel leaves roughly 200 kg of slag. A road built entirely with processed steel slag was laid at Surat in 2022. Slag from the blast furnace goes into Portland slag cement.