# Why Do We Find Plastic Limit Of Soil?

## 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..

## 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).

## How is plastic limit calculated?

Record the difference between the wet and dry weights as the weight of moisture. Calculate the plastic limit wp by dividing the “weight of moisture” by the “dry weight of sample” and multiply by 100. Plasticity Index (Ip) of a soil is the numerical difference between its Liquid Limit and its Plastic Limit.

## What is liquid limit in soil mechanics?

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.

## What is the plastic limit of soil?

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 does the plastic limit tell you?

Plastic Limit Definition The soil moisture content at which any increase in the moisture content will cause a semi-solid soil to become plastic. The limit is defined as the moisture content at which a thread of soil just crumbles when it is carefully rolled out to a diameter of 1/8 inch.

## What do the liquid limit and plastic limit tell you about the soil?

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.

## Why is plastic limit important?

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 does plastic soil mean?

“Plastic soil” generally means the soil is predominantly clay – and the more plastic the soil, the more expansive it will likely be. The soil’s plasticity is measured by two tests: the Plastic limit and the Liquid limit.

## Why are plastic limits and liquid limits important?

The liquid and plastic limits of a soil define the range within which a cohesive soil behaves in a plastic state. The value of the Atterberg limits of a cohesive soil depends upon several factors, including the quantity and type of clay mineral and type of absorbed cation.

## Why do we find the liquid limit of soil?

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.

## 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.

## What is shrinkage limit of soil?

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.