Engineering behavior of clay-sand mixtures with same liquid limit may be different due to clay type and content. It is known that the standards suggest classifying fine-grained soils by incorporating different amounts and types of clays based on their plasticity which is a function of the liquid and plastic limit, rather than activity. This rule could be used to verify the compatibility of the liquid limits results by following two different standards for control purpose. The obtained results indicated that the liquid limit values measured by the American and British standards are governed by a specific rule depending on the silt and the clay fractions of the soil. Then, the liquid limit for these soils was measured through the above two mentioned methods. First of all, the author 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. It appeared that the fall cone test is more reliable than the Atterberg test and therefore it is important to make this comparison.
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).