Liquid limit test

A standard test to determine the liquid limit of a sample.

The standard liquid limit test apparatus was designed by Arthur Casagrande in the 1930s based on the procedure developed by Albert Atterberg; therefore, the liquid limit test is sometimes called the Casagrande test. The test apparatus consists of a Casagrande cup, also known as the liquid limit device , and a Casagrande grooving tool.

Soil is patted smooth across the brass cup to a thickness of 10 mm. The grooving tool is used to make a groove completely through the soil pat that is 2 mm wide at the bottom, 11 mm wide at the top, and 8 mm deep (ASTM 2010). The brass cup is hinged on one edge so that a cam shaft with a hand-operated crank can be used to raise the cup and allow it to drop abruptly 10 mm onto a hard rubber base at a rate of 120 drops per minute. The number of drops required to cause the soil to flow from both sides to close the groove over a distance of 12.7 mm is recorded; a...