What unique measure is recommended to be taken for each sieve during hand sieving?

The recommendation to maintain the same number of strikes for each sieve during hand sieving is key to achieving accurate and reliable results when analyzing aggregate samples. Consistency in the number of strikes helps to ensure that each fraction of the sample is subjected to the same amount of mechanical action, which leads to uniformity in the sieving process. This uniformity allows for a more precise assessment of the material's gradation, which is critical for quality control in asphalt production.

Using different techniques for each sieve would introduce variability that could impair the accuracy of the gradation results. Similarly, applying a consistent angle of impact could be useful, but without the control of the number of strikes, variations can still occur. Weighing each sieve separately does not contribute to the consistency of the sieving process itself; it’s more about measuring the collected material than ensuring the process is uniform across all sieves. By keeping the number of strikes uniform, the process adheres to established standards and practices necessary for reliable quality assessments in asphalt mix design and production.