The fine aggregate in concrete is usually made of which material?

• A. Gravel
• B. Sand
• C. Crushed stone
• D. Cement

Answer: (B)

Fine aggregate is the portion of the aggregate fraction with small particle size that fills the voids between larger particles to make a dense, workable concrete mix. Sand is used as the fine aggregate because its small particles readily fill the gaps between coarse aggregates, improving workability, compaction, and the overall density of the mix. It helps reduce the amount of cement paste needed and contributes to a smoother surface finish when properly graded and clean (free of silt, clay, and other deleterious materials).

Coarse aggregates like gravel or crushed stone provide the skeletal structure of the concrete with larger particles, while cement acts as the binder that holds everything together. Since cement is not an aggregate, it isn’t the material used for the fine portion of the aggregate fraction.