What is the total number of strikes required in the hand sieving process per minute?

In the hand sieving process, the standardized practice specifies that the total number of strikes should be 150 strikes per minute. This figure is established to ensure effective separation of aggregate particles during testing, contributing to accurate assessment of the material's gradation.

Achieving 150 strikes per minute allows for a consistent and uniform sieving action, ensuring that the larger aggregates are adequately separated from finer particles. This level of activity helps minimize the risk of errors during the testing phase, directly enhancing the reliability of the material evaluation.

The other options suggest either too few or too many strikes, which can lead to insufficient agitation during sieving or excessive fatigue without further benefit to the separation process, thus impacting the integrity of the results.