In what manner is gradation typically tested?

Gradation is a key aspect in the testing of aggregates, which involves determining the distribution of different particle sizes within a material. The most widely accepted and effective method to test gradation is by sieving. In this process, a series of progressively smaller mesh screens (sieves) are used to separate the aggregate into different size categories.

When a sample of aggregate is placed on the top sieve and shaken, the larger particles remain on the top screens while smaller particles pass through and are collected on lower screens. This allows for a clear quantitative analysis of the particle sizes in the sample, which can be important for various applications in construction and engineering. The results can then be used to ensure that the aggregate meets specific gradation requirements for concrete, asphalt, or other materials.

Other methods, while they may have their applications, do not provide the same level of precise sizing information. Visual inspection lacks objectivity and accuracy, weighting with tools does not measure particle size distribution, and liquid displacement is not a common method employed specifically for testing gradation. Thus, sieving stands out as the preferred method for its accuracy and reliability in determining gradation.