What is the function of a mechanical shaker in aggregate testing?

The function of a mechanical shaker in aggregate testing is to perform sieve analysis for classifying particle sizes. This process involves using a series of sieves with different mesh sizes placed on top of each other. The mechanical shaker vibrates the stacked sieves, allowing the aggregates to move through the openings of the sieves, thereby separating the particles based on size.

As the material passes through the sieves, the larger particles remain on the coarser sieves while the finer particles are collected on the smaller sieves. This systematic classification is essential for understanding the gradation of the aggregate, which directly impacts the performance characteristics of the construction materials, such as concrete or asphalt. Proper gradation helps ensure effective compaction, strength, and stability in the final mix.

While the other choices involve important aspects of aggregate testing, they do not pertain to the function of a mechanical shaker. For instance, measuring moisture content involves a different method, determining density typically requires weighing aggregate samples and volume determination, and mixing aggregates generally occurs through a different process, not specifically with a mechanical shaker designed for separation.