Should you add coarse or fine sand to concrete?
November.10,2025
Sand can be classified as coarse, medium, and fine sand according to its fineness modulus. Coarse sand has a fineness modulus of 3.7–3.1, medium sand 3.0–2.3, fine sand 2.2–1.6, and extra-fine sand 1.5–0.7. Different fineness moduli affect the performance of concrete differently.
Medium sand is best for preparing concrete. For concrete requiring higher strength, coarser sand, such as slightly coarse medium sand or slightly fine coarse sand, is preferable. For concrete requiring lower strength, finer sand, such as slightly coarse fine sand or slightly fine medium sand, is preferable. With the same mix proportions, if the sand is too coarse, the resulting concrete will have poor cohesion, easily leading to segregation and bleeding. If the sand is too fine, although the resulting concrete will have better cohesion, its fluidity will be significantly reduced, requiring more cement to meet fluidity requirements. Therefore, the sand used in concrete should not be too coarse or too fine.
