Detailed Explanation:

Answer: Option 4 — 1, 2 and 3 only

Steel slag, a by-product of steel manufacturing, has multiple applications in construction, agriculture, and cement production. All three statements correctly identify valid uses of steel slag.

✅ Statement 1 – Correct: Steel slag is widely used in road base construction due to its high strength, durability, excellent drainage properties, and cost-effectiveness.

✅ Statement 2 – Correct: Steel slag can be used as a soil amendment in agriculture to improve drainage, provide essential nutrients like calcium and magnesium, correct soil pH, and enhance soil structure.

✅ Statement 3 – Correct: Steel slag can be used as a partial substitute for limestone and other raw materials in cement production, reducing environmental impact and conserving natural resources.

📝 Short Notes: Steel Slag Utilization

• Definition: Steel slag is a by-product generated during steel manufacturing in furnaces, consisting primarily of calcium, iron, silicon, and magnesium oxides.
• Road Construction: Used as aggregate in asphalt concrete, road base material, and railway ballast due to high abrasion resistance and load-bearing capacity.
• Agricultural Use: Acts as a soil conditioner, neutralizes acidic soils, supplies micronutrients, and improves soil permeability.
• Cement Industry: Can replace 10-15% of clinker in cement production, reducing CO₂ emissions and energy consumption.
• Other Applications: Used in wastewater treatment, coastal protection structures, and as a raw material for mineral wool production.
• Environmental Benefits: Reduces landfill waste, conserves natural resources, and supports circular economy principles in steel industry.