Effect of the Silt and Clay Fractions on the Liquid Limit Measurements by Atterberg Cup and Fall Cone Penetrometer

There are two widely used methods to determine the liquid limit of a soil; the Atterberg cup according to the American Society for Testing and Materials (ASTM) and the fall cone penetrometer according to the British Standards (BS). It appeared that the fall cone test is more reliable than the Atterberg test and therefore it is important to make this comparison. First of all, we collected twenty-nine samples from the Lebanese territory in order to identify them through many laboratory experiments such as the sieve analysis, the plastic limit, the specific gravity, the soil classification and the hydrometer. Then, the liquid limit for these soils was measured through the above two mentioned methods. The obtained results indicated that the liquid limit values measured by the American and British standards are governed by specific rule depending on the silt and the clay fractions of the soil. This rule could be used to verify the compatibility of the liquid limits results by following two different standards for control purpose