What does a sieve size of No. 4 indicate?

A sieve size of No. 4 specifically refers to the number of openings in the sieve. In the context of sieve standards, a No. 4 sieve corresponds to a mesh size that has 4 openings per linear inch, and each opening is equivalent to a specific size, which typically measures about 4.75 mm (or approximately 0.187 inches) in diameter.

This designation is part of a standardized series used in sieving materials, particularly in construction and civil engineering, to classify aggregates or describe the size distribution of particles. As a general rule, as the sieve number increases, the particle size that can pass through the sieve generally decreases.

Understanding this terminology is crucial for interpreting sieve analysis results, which are used to ensure that materials meet specified sizes for construction purposes, such as concrete mixes or road bases where particle size distribution can affect the material’s performance.