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.
How are Atterberg limits related to soil composition?
Atterberg Limits are the water contents which define transitions between the solid, plastic, and liquid states of a given soil material . The tests are restricted to cohesive soils with appreciable silt or clay fraction, and cannot be conducted readily on either sands or silts with a high sand fraction.
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.
Why liquid limit test is important?
Liquid limit of soil can be used to predict the consolidation properties of soil while calculating allowable bearing capacity & settlement of foundation . Liquid limit value of soil is also used to calculate activity of clays and toughness index of soil.
What are the three 3 Atterberg limits?
7.3. 3 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 are the significance of consistency limits?
A gradual increase in water content causes the soil to change from solid to semi-solid to plastic to liquid states . The water contents at which the consistency changes from one state to the other are called consistency limits (or Atterberg limits).
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.
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.
Is high plasticity clay good?
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. The plasticity index also gives a good indication of compressibility (see Section 10.3). The greater the PI, the greater the soil compressibility.
What is Pi in soil test?
The plasticity index (PI) is a measure of the plasticity of a soil. The plasticity index is the size of the range of water contents where the soil exhibits plastic properties. The PI is the difference between the liquid limit and the plastic limit (PI = LL-PL).
What type of soil is sticky when wet and hard when dry?
Clay is the smallest of particles. Clay is smooth when dry and sticky when wet. Soils high in clay content are called heavy soils. Clay also can hold a lot of nutrients, but doesn’t let air and water through it well.
Which kind of soil holds the most water?
The clay soil had the highest water holding capacity and the sand soil had the least; clay>silt>sand. Clay particles are so tiny and have many small pore spaces that make water move slower (the highest water holding capacity). Sandy soils have good drainage but low water and nutrient holding capacities.
Can liquid limit be less than plastic limit?
If the plastic limit cannot be determined, then report the plasticity index as NP (non-plastic). c) When the plastic limit is equal to or greater than the liquid limit, report the plasticity index as NP (non-plastic). ... It gives the range in moisture at which a soil is in a plastic state.
What is the value of liquid limit?
| Soil Liquid limit w L (%) Plastic limit w p (%) | Silt, medium plasticity 35–50 22– 23 | Clay, low plasticity 25–35 15–22 | Clay, medium plasticity 40–50 18–25 | Clay, high plasticity 60–85 20–35 |
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Why plastic limit test is done?
Plastic limit test is one of the laboratory tests used internationally to differentiate or classify soils into groups . ... When the water content or moisture content of soil increases beyond a limit then the soil starts to behave as liquid.
