When should a mechanical splitter be used for fine aggregates?

A mechanical splitter is specifically used for fine aggregates to ensure a representative sample is obtained while minimizing handling losses and variations. The optimum time to use a mechanical splitter is when the fine aggregate is drier than the Saturated Surface Dry (SSD) condition. This condition allows for effective splitting without material sticking together or forming clumps, which can occur when the aggregate is too moist.

When the fine aggregate is at SSD, it means it has absorbed just enough moisture to be at a balanced state, and any additional moisture may lead to inaccuracies in sampling due to stickiness or clumping. Hence, using a mechanical splitter under dry conditions enhances the accuracy and reliability of the sample by ensuring that the material flows freely through the splitter without obstruction.

In contrast, when aggregates are wetter than SSD or when free moisture is present, the moisture can cause the fine material to adhere to surfaces, which may result in uneven sampling and the potential for an unrepresentative sample. Additionally, mixing fine aggregates with coarse aggregates typically falls under a different sampling protocol and wouldn't require a mechanical splitter for fine aggregates specifically.