What are the three primary components of modern concrete?

• A. Portland cement, aggregate, and water
• B. Lime, sand, and water
• C. Portland cement, lime, and water
• D. Water, aggregate, and steel

Answer: (A)

The key idea is that modern concrete relies on a cementitious binder, a bulk filler, and water. Portland cement acts as the binder that chemically hardens when it reacts with water. The aggregate, usually a mixture of sand and gravel, provides most of the volume and strength, while reducing shrinkage. Water is essential to trigger the hydration of the cement, turning the mixture into a solid matrix as it cures. Lime with sand and water would be a lime mortar from older practices, not modern concrete. Steel is used for reinforcement in reinforced concrete, but it’s not part of the basic mix itself. So the three primary components are Portland cement, aggregate, and water.