What is the minimum sieve diameter for coarse aggregates?

The minimum sieve diameter for coarse aggregates is defined as 4.75 mm (or approximately 0.187 inches), which corresponds to the No. 4 sieve in the ASTM standard. When considering what's often categorized as "coarse aggregates" in a practical sense, they are typically those aggregates retained on a No. 4 sieve, which means aggregates that are larger and typically characterized as such begin at this size.

The choices given indicate larger sieve sizes, reflecting sizes that might be used in classifications broader than just the minimum for coarse aggregate. When considering standards for construction aggregate, a sieve opening of 4 inches, 6 inches, or even 10 inches can generally categorize materials, but the critical cutoff point for defining a material as "coarse" in a technical sense starts clearly at the 4.75 mm mark. Hence, while the question may suggest different sizes, the definition is firmly based around that minimum size effectively distinguishing fine aggregates from coarse aggregates, thereby establishing why the other sizes do not qualify as the minimum for coarse aggregates.

In summary, while the initial options seem to imply different sizes used in aggregates, the foundational standard of 4.75 mm clearly demarcates the transition from fine to coarse aggregates, setting a