vätskegräns

Vätskegräns, or liquid limit, is a concept used in soil mechanics to describe the water content at which a soil transitions from a plastic to a liquid state. It is one of the Atterberg limits, a set of empirical values that characterize the mechanical behavior of fine-grained soils. The liquid limit is determined through standardized laboratory tests, most commonly the Casagrande liquid limit device or the fall cone test. In the Casagrande method, a standardized groove is made in a soil paste, and the device is used to repeatedly drop the sample from a height of 1 cm. The liquid limit is defined as the water content at which the groove closes after 25 drops. The fall cone test involves dropping a cone of specific mass and angle into the soil; the liquid limit is the water content at which the cone penetrates a specific depth (typically 20 mm).

The liquid limit is a crucial parameter for classifying soils and predicting their behavior. Soils with higher liquid limits are generally considered more susceptible to changes in moisture content and can exhibit more significant volume changes, such as swelling and shrinking. This property is particularly important in civil engineering for assessing the suitability of soil for construction purposes, designing foundations, and understanding slope stability. The liquid limit, along with the plastic limit and shrinkage limit, helps engineers determine the plasticity index, which further quantifies the range of water content over which a soil behaves plastically.