2.1 The liquid limit of a soil is the moisture content, expressed as a percentage of the weight of the oven-dried soil , at the boundary between the liquid and plastic states of consistency.
How is liquid limit calculated?
The tester places soil samples with varying water contents into the cup of the device, then cuts a groove through the sample. The cup is dropped multiple times until soil fills the groove. Use the number of drops along with the water content of the samples to calculate the liquid limit.
What does the liquid limit tell us?
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 considered a high liquid limit?
| I p Description | 5–10 Low plasticity | 10–20 Medium plasticity | 20–40 High plasticity | > 40 Very high plasticity |
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Is plastic index a percentage?
The plasticity index is expressed in percent of the dry weight of the soil sample . It shows the size of the range of the moisture contents at which the soil remains plastic. In general, the plasticity index depends only on the amount of clay present. ... The greater the PI, the greater the soil compressibility.
What are the three Atterberg limits?
There are three important Atterberg limits: shrinkage limit (SL), plastic limit (PL), and liquid limit (LL) . The shrinkage limit is the water content at which the volume of the soil starts to increase.
What is the plastic limit?
DEFINITION. 2.1 The plastic limit of a soil is the moisture content , expressed as a percentage of the weight of the oven-dry soil, at the boundary between the plastic and semisolid states of consistency. It is the moisture content at which a soil will just begin to crumble when rolled into a thread 1⁄8 in.
Can liquid limit be more than 100%?
Atterberg limits cannot exceed 100 . d. In AASHTO, A-7-5(30) is a better subgrade material than A-7-5(15). e.
Why liquid limit test is done?
If the natural moisture content of soil is higher than liquid limit, the soil can be considered as soft and if the moisture content is lesser than liquid limit, the soil is brittle and stiffer. The value of liquid limit is used in classification of the soil and it gives an idea about plasticity of the soil .
What is the difference between liquid limit and plastic limit called?
The difference between the liquid limit and the plastic limit is known as the plasticity index (I P ) , and it is in this range of water content that the soil has a plastic consistency. The consistency of most soils in the field will be plastic or semi-solid.
What is the use of liquid limit?
Value of liquid limit is used to classify fine grained soil . It gives us information regarding the state of consistency of soil on site. Liquid limit of soil can be used to predict the consolidation properties of soil while calculating allowable bearing capacity & settlement of foundation.
Is code for Atterberg limits?
STANDARD • IS: 2720 (Part 5) 1985. DEFINITION • Liquid Limit is defined as the water content at which the soil changes from liquid state to plastic state. APPARATUS • Casagrande apparatus confirming to IS: 9259-1979. Grooving tool.
What is void ratio formula?
Soil void ratio (e) is the ratio of the volume of voids to the volume of solids : e = (V_v) / (V_s) Where V_v is the volume of the voids (empty or filled with fluid), and V_s is the volume of solids.
What is the purpose of Atterberg limits?
The limits relate the determined moisture contents to empirically defined boundaries between states of consistency (liquid, plastic and solid) (Baver et al., 1972). The aim of the Atterberg limit tests is to obtain empirical information on the reaction of regolith to water .
What is considered high pi soil?
Soils with a high PI tend to be clay . Soils with a low PI tend to be silt. Soils with a PI of zero or less are considered non-plastic and usually have little or no clay or silt.
What is the shrinkage limit?
The shrinkage limit (SL) is defined as the water content at which the soil changes from a semi-solid to a solid state . At this moisture content the volume of the soil mass ceases to change with further drying of the material. The shrinkage limit is less frequently used than the liquid and plastic limits.
