How do you calculate plastic limit and liquid limit?

How do you calculate plastic limit and liquid limit?

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.

Why is there 25 blows in liquid limit?

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.

Is code for liquid limit and plastic limit?

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 liquid limit and plastic index?

1.1 The plasticity index of a soil is the numerical difference between its liquid limit and its plastic limit, and is a dimensionless number. Both the liquid and plastic limits are moisture contents. 3.1 Report the calculated difference as indicated in 2.1 as the plasticity index.

Is liquid limit a percentage?

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.

What is the liquid limit?

Liquid limit (LL) is defined as a limiting water content separating the viscous liquid state and plastic state of soil consistency.

What is the range of liquid limit of soil?

9.2. 1 Consistency and Plasticity

Soil	Liquid limit wL (%)	Plastic limit wp (%)
Silt, low plasticity	25–35	20–28
Silt, medium plasticity	35–50	22–23
Clay, low plasticity	25–35	15–22
Clay, medium plasticity	40–50	18–25

What is the liquid limit of the soil?

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 is the difference between liquid limit and plastic limit is called?

The difference between the liquid limit and the plastic limit is known as the plasticity index (IP), 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.

How is the liquid limit of water determined?

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. Good it is better than book…

How to calculate the liquid limit of soil?

When using the single point method, the following equation is used to determine the liquid limit: LL = MC ∗ N 25 0.121 (1.2) Where: LL = the soil’s liquid limit N = the number of blows until the soil groove closed MC = the soil’s water content 1.3 Plastic Limit

What’s the difference between liquid limit and plastic limit?

The difference between liquid and plastic limits is called the plasticity index, and it represents the range of water content over which the soil is plastic. The plasticity index, in combination with water content at liquid limit (wL), indicates how sensitive the soil is to the changes in moisture content.

How to calculate the liquid limit of a thread?

The values of liquid limit are required to calculate flow index, toughness index etc. From the 20g sample select a 1.5 to 2 g specimen for testing. Roll the test specimen between the palm or fingers on the ground glass plate to from a thread of uniform diameter. Continue rolling the thread until it reaches a uniform diameter of 3.2mm or 1/8 in.