What is an appropriate size of mesh to define the material finer for test C117?

For test C117, which involves determining the amount of material finer than a certain size, the appropriate mesh size is specified as a No. 200 sieve. This sieve size allows for the accurate measurement of fine particles that pass through, which is crucial for assessing the properties of soil and aggregates.

Using the No. 200 sieve ensures that particles less than 0.075 mm (75 micrometers) are effectively captured in the analysis. The significance of this particular mesh size lies in its ability to identify fine contents that may influence the soil's engineering properties, such as its plasticity and strength.

When other sieve sizes, like the No. 100 or No. 50, are considered, they measure larger particles and do not focus specifically on the smaller fractions that are critical for classifying soils and aggregates in accordance with specification requirements. The No. 400 sieve is too fine for this test, as it is not the standard size used for the purpose of defining material finer, which is why it also does not meet the criteria set forth in the C117 test.