Quick Answer: How Is Plastic Limit Calculated?

What is plastic limit?

The plastic limit is the water content at which a soil-water paste changes from a semisolid to a plastic consistency as it is rolled into a 3.175-mm (1/8-inch) diameter thread in a standard test..

Why are plastic limits and liquid limits important?

This is very important when trying to build with or build on these type of materials. The two commonly determined Atterberg Limits represent the moisture contents at which a specific soil’s behavior changes from solid to plastic (Plastic Limit) and from plastic to liquid (Liquid Limit).

What is the use of plastic limit test?

Plastic limit test is one of the laboratory tests used internationally to differentiate or classify soils into groups. As the starting procedures of liquid limit test and plastic limit test are common, the both tests are executed at the same time in most of the purposes.

What is shrinkage limit of soil?

The shrinkage limit of soil is the water content of the soil when the water is just sufficient to fill all the pores of the soil and the soil is just saturated. The volume of the soil does not decrease when the water content is reduced below the shrinkage limit. Shrinkage limit can be determined from the relation.

How do you find Atterberg limits?

Liquid LimitPlace a soil paste in the cup.Cut a groove at the center of the soil paste with the standard grooving tool.Lift the cup and drop it from a height of 10mm, using the crank-operated cam. … Repeat the procedure at least three times for the same soil at varying moisture contents.More items…

What is plastic state of soil?

A soil is in the liquid state when it acts as a viscous liquid when jarred. A soil is in the plastic state when it can be molded in different shapes. A soil is friable when moist soil crumbles into aggregates when crushed with only light pressure. … The plastic limit is the limit between the friable and plastic state.

Why is there 25 blows in liquid limit?

7.3. The liquid limit is the moisture content at which the groove, formed by a standard tool into the sample of soil taken in the standard cup, closes for 10 mm on being given 25 blows in a standard manner. At this limit the soil possess low shear strength.

What does liquid limit tell you?

The liquid limit is the moisture content at which the groove, formed by a standard tool into the sample of soil taken in the standard cup, closes for 10 mm on being given 25 blows in a standard manner. This is the limiting moisture content at which the cohesive soil passes from liquid state to plastic state.

How is liquid limit calculated?

x) Liquid limit is determined by plotting a ‘flow curve’ on a semi-log graph, with no. of blows as abscissa (log scale) and the water content as ordinate and drawing the best straight line through the plotted points. Report the water content corresponding to 25 blows, read from the ‘flow curve’ as the liquid limit.

What is 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 a good plasticity index?

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. The plasticity index also gives a good indication of compressibility (see Section 10.3).

Why do we find plastic limit of soil?

The plastic limit (PL) is the water content, in percent, at which a soil can no longer be deformed by rolling into 3.2 mm (1/8 in.) … Those limit of soil are very important property of fine grained soil and its Value is used to classify fine grained soil and calculate activity of clays and toughness index of soil.

What is plastic limit of soil?

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 ⅛ in.

What is Atterberg limit of soil?

The Atterberg limits are a basic measure of the critical water contents of a fine-grained soil: its shrinkage limit, plastic limit, and liquid limit. Depending on its water content, a soil may appear in one of four states: solid, semi-solid, plastic and liquid.