What is considered excessive wear on the rim of the liquid limit cup?

Excessive wear on the rim of the liquid limit cup is recognized at the point where it becomes significantly thinner due to frequent use or improper handling. The threshold for this wear is typically established at one-half of the original thickness. When the rim has worn down to this extent, it can compromise the accuracy of testing because the cup may no longer behave as intended during tests.

In liquid limit testing, the precision of measurements is critical, and any alteration in the rim could affect the ability to determine the correct limits of the soil sample. Worn rims can lead to inconsistencies in results as they might change how the soil interacts with the cup during testing, potentially skewing the reading of the moisture content at which the soil transitions from a plastic to a liquid state.