What equipment is primarily used to determine the size distribution of coarse aggregates?

The mechanical sieve shaker is primarily used to determine the size distribution of coarse aggregates because it provides a systematic and efficient method of separating aggregate particles into different size fractions. This equipment uses a series of sieves with varying mesh sizes, allowing aggregates to be classified according to their dimensions.

When a sample is placed in the shaker, it rapidly vibrates, causing the particles to move through the sieve openings, thereby allowing larger particles to remain on the top sieves while smaller ones pass through to lower sieves. This separation process enables inspectors to ascertain the proportion of different particle sizes, which is crucial for quality control in construction and material specifications.

This method is preferred over others for a few reasons: it minimizes human error, ensures consistent results through mechanical operation, and allows for testing larger batches of material in a shorter time frame. Other methods, such as manual sieves, require more time and can be less accurate due to variations in human technique or energy applied to shake the sieve. The hydrometer is typically used for fine aggregates and soil analysis rather than coarse aggregates, while an oven is used primarily for drying samples and measuring moisture content, not for size distribution.