# What is the group index classification of soil?

## What is the group index classification of soil?

Group Index is a number assigned to the soil based on its physical properties like particle size, Liquid limit and plastic limit. It varies from a value of 0 to 20, lower the value higher is the quality of the sub-grade and greater the value, poor is the sub-grade.

What are the six categories of soil types identified in the ASTM classification system?

The soil type designations used by FHWA follow ASTM D 2487; i.e., gravel, sand, silt, clay, organic silt, organic clay, and peat.

What is the purpose of the group index in the Aashto classification system?

The AASHTO Soil Classification group index (GI) is used to evaluate the quality of highway subgrade material. GI is calculated using the formula shown here and test results for percent passing the #200 sieve, LL, and PI. F equals the percentage passing the #200 sieve.

### What is the formula of Group Index?

G.I = 0.2 a + 0.005 ac + 0.01 bd c = It is the portion of the numerical liquid limit greater than 40 but not exceeding 60 expressed as whole number in between [0-20].

What is Class C soil?

Type C Soils are cohesive soils with an unconfined compressive strength of 0.5 tsf (48 kPa) or less. Other Type C soils include granular soils such as gravel, sand and loamy sand, submerged soil, soil from which water is freely seeping, and submerged rock that is not stable.

What are the factors that determine soil formation class 8?

Climate, , flora and fauna, altitude, and are the five major factors that contribute to soil formation.

## What is GW soil?

The soil is classified as a WELL GRADED GRAVEL (GW), or as a WELL GRADED SAND (SW), if a wide range of particle sizes and substantial amounts of the intermediate particle sizes are present.

How do you determine D10 D30 and D60?

The particle diameters defining 10%, 30%, and 60% finer from the grain-size distribution curve are estimated as: D10 = 0.14 mm , D30 = 0.27 mm, and D60 = 0.42 mm.

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