What is the main difference between performing gradation tests on fine and coarse aggregates?

The main difference between performing gradation tests on fine and coarse aggregates lies in the sieving techniques used for each type of aggregate. Fine aggregates, typically consisting of particles that pass through the No. 4 sieve, require a different approach compared to coarse aggregates, which primarily consist of particles that retain on the No. 4 sieve.

For fine aggregates, testing often involves using smaller sieve sizes, accompanied by specific methods to ensure that all particles are adequately separated and that the test accurately reflects the distribution of particle sizes. This might include utilizing additional techniques such as hydrometer analyses when necessary to account for very fine particles that may not be effectively characterized by standard sieving alone.

Coarse aggregates, on the other hand, can be evaluated using larger sieve sizes and tend to be separated through more straightforward mechanical sieving. The characteristic difference in the physical properties and size distributions of the aggregates necessitates these distinct sieving techniques to ensure accurate gradation results.

Recognizing the importance of appropriate methods for different aggregate types emphasizes the need for adapting testing procedures to the material being assessed, thus ensuring quality control in the production of concrete and similar materials.