Concrete is made by mixing cement, ____________, coarse aggregate and water.

• A. sand
• B. lime
• C. gypsum
• D. ash

Answer: (A)

Concrete is made by combining cement with water to form a paste that coats rigid particles of aggregate. The missing piece is sand, which acts as the fine aggregate. Sand fills the small voids between the larger chunks of coarse aggregate, helping to create a dense, workable mixture that bonds well with the cement paste. This combination—cement, water, fine aggregate (sand), and coarse aggregate—gives concrete its strength and durability.

Lime is a binder used in older lime mortars rather than modern concrete, so it wouldn’t serve as the correct fine aggregate. Gypsum is used in some cement formulations or plasters but not as the standard fine aggregate in concrete. Ash (fly ash) is typically added as a supplementary cementitious material to replace part of the cement, not used in place of sand as the fine aggregate.