What do Atterberg limits tell us?

In the field, the Atterberg Limits, can be used as a guide indicating how much a soil is likely to settle or consolidate under load. If the field moisture is near the liquid limit, a lot of settlement is likely. The opposite is true if the field moisture is near or below the plastic limit.

What is plasticity limit?

Plastic limit is defined as the water moisture content at which a thread of soil with 3.2mm diameter begins to crumble.

What does the plasticity index tell you?

In general, the plasticity index depends only on the amount of clay present. It indicates the fineness of the soil and its capacity to change shape without altering its volume. A high PI indicates an excess of clay or colloids in the soil. Its value is zero whenever the PL is greater or equal to the LL.

What is the relation between liquid limit and plastic limit?

Liquid Limit (LL) is the water content at which soil changes from a plastic to a liquid state when the soil specimen is just fluid enough for a groove to close when jarred in a specified manner. Plastic Limit (PL) is the water content at the change from a plastic to a semi-solid state.

What is plasticity of soil?

2 Plasticity. Plasticity is the ability of a material to undergo permanent deformation under stress without cracking. Fine-grained soils become plastic as their moisture content is increased, leading to loss in shear strength and stability.

How do you determine the plasticity index of soil?

Calculate the plasticity index as follows: PI = LL ‑ PL where: LL = liquid limit, and PL = plastic limit.

What are the three Atterberg limits?

6.3 Atterberg Limits. Fine-grained soil (silt and clay) can appear in different states of consistency, solid, plastic and liquid, for which the boundaries are defined in terms of Atterberg limits, based on moisture content. The two limits associated with plasticity of soil are liquid limit (LL) and plastic limit (PL).

Why do we use plastic limits?

1. The value of the plastic limit is used to classify the fine-grained soils and evaluating the activities of clayey soil. 2. It indicates the toughness index of soil.

What is the concept of plasticity?

1 : the quality or state of being plastic especially : capacity for being molded or altered. 2 : the ability to retain a shape attained by pressure deformation. 3 : the capacity of organisms with the same genotype to vary in developmental pattern, in phenotype, or in behavior according to varying environmental …

What happens if plasticity index increases?

As the plasticity index Ψ increases, the condition of asperity contacts becomes severe. Consequently, with a large value of Ψ, high friction and high surface temperature were observed. Furthermore, the progress of oil film formation became very slow.

Is liquid limit always greater than plastic limit?

Liquid limit is always greater than plastic limit. b. Plasticity index can be less than plastic limit.

What is Atterberg limit of soil?

Atterberg limits are a basic measure of the critical water contents of fine-grained soils, such as silt and clay, as they transition from a solid to a liquid. Atterberg Limits are an inexpensive and well documented way of predicting the engineering properties of silt and clay soils.