What does the plasticity index tell you?
In general, the plasticity index depends only on the amount of clay present. 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. The greater the PI, the greater the soil compressibility.
What is plasticity chart?
Plasticity chart is a graph between plasticity index (IP) and liquid limit (WL) in percentage which is used for classification of fine-grained soils as per the Indian Standard Soil Classification System(ISSCS). If more than 50% percent of soil passes through 75micron sieve, then it is classified as fine-grained soil.
Why do we use plasticity chart?
The Casagrande plasticity chart has been used for more than 70 years to classify fine-grained soils in accordance with the USCS. The majority are classified in the field as SILT, whereas these same soils are classified by the plasticity chart as CLAY.
What is the plasticity index formula?
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 is a toughness index?
Toughness Index: Toughness index is defined as the ratio of plasticity index (IP) of the soil to the flow index (IF) of the soil. Toughness index varies between 0 to 3. This gives us an idea of shear strength of soil at its plastic limit.
How do you calculate plasticity?
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 are the 3 types of soil?
The particles that make up soil are categorized into three groups by size – sand, silt, and clay. Sand particles are the largest and clay particles the smallest. Most soils are a combination of the three. The relative percentages of sand, silt, and clay are what give soil its texture.
How do you read a plasticity chart?
A plasticity chart , based on the values of liquid limit (WL) and plasticity index (IP), is provided in ISSCS to aid classification. The ‘A’ line in this chart is expressed as IP = 0.73 (WL – 20). Depending on the point in the chart, fine soils are divided into clays (C), silts (M), or organic soils (O).
What is Liquidity Index?
The liquidity index calculates the days required to convert a company’s trade receivables and inventory into cash. The index is used to estimate the ability of a business to generate the cash needed to meet its current liabilities. It is commonly used by credit analysts to evaluate the creditworthiness of customers.
Which soil has maximum plasticity?
Soils with a high PI tend to be clay, Those with a lower PI tend to be silt, and.