Emerson flowchart
1. Emerson Class numbers
The Emerson Class number system measures the likelihood of soil, when in contact with water, produces a murky cloud of particles. The number system considers the soil consistency that can be used to identify how dispersive the soil is. This, in turn, aids in the identification of soils that produce ‘dirty water’ where the sedimentation of these particles can harm plant and animal life.
2. Soil Classification
2.1 Atterberg Limits
Atterberg limits are used to categorize fine-grained soils through measuring the boundary in which the soil behavior changes through a series of tests.
The plastic limit is the lowest water content that a soil can be classified as plastic before its transition to semi-solid states. A common method to test a soil’s plasticity is by dampening the sample and rolling it out into a fine thread on a non-porous surface. If the thread retains its shape at the diameter of 3mm, it is considered plastic.
The liquid limit is defined as the boundary at which a soil transitions from plastic to a semi-liquid state. A way to test the liquid limit is by dampening a sample of soil and spreading it out over a round-bottomed porcelain bowl and cutting a groove through the center and measuring how many blows (when the bowl is lifted up and down a distance of 1cm) it takes to fill the groove.
2.2 Classify soils
Table 1: Soil classifications for soils A to E
Soil
Notes on classification
Description
A
Using particle size distribution graph; sieve #200 82% pass and sieve #4 100% pass
First letter is C or M
Use plasticity chart to determine second letter
LL = 80, PI = 50
CH
CH, clay with some sand, high plasticity, grey.
B
Using particle size distribution graph; sieve #200 60% pass and sieve #4 100% pass
Greater than 50% pass sieve #200 therefore first letter is M or C
Use Atterberg limits to determine suffix (used a hydrometer for soil B)
CL
CL, clay and silt with some sand, low to medium plasticity, brown.
The Emerson Class number system measures the likelihood of soil, when in contact with water, produces a murky cloud of particles. The number system considers the soil consistency that can be used to identify how dispersive the soil is. This, in turn, aids in the identification of soils that produce ‘dirty water’ where the sedimentation of these particles can harm plant and animal life.
2. Soil Classification
2.1 Atterberg Limits
Atterberg limits are used to categorize fine-grained soils through measuring the boundary in which the soil behavior changes through a series of tests.
The plastic limit is the lowest water content that a soil can be classified as plastic before its transition to semi-solid states. A common method to test a soil’s plasticity is by dampening the sample and rolling it out into a fine thread on a non-porous surface. If the thread retains its shape at the diameter of 3mm, it is considered plastic.
The liquid limit is defined as the boundary at which a soil transitions from plastic to a semi-liquid state. A way to test the liquid limit is by dampening a sample of soil and spreading it out over a round-bottomed porcelain bowl and cutting a groove through the center and measuring how many blows (when the bowl is lifted up and down a distance of 1cm) it takes to fill the groove.
2.2 Classify soils
Table 1: Soil classifications for soils A to E
Soil
Notes on classification
Description
A
Using particle size distribution graph; sieve #200 82% pass and sieve #4 100% pass
First letter is C or M
Use plasticity chart to determine second letter
LL = 80, PI = 50
CH
CH, clay with some sand, high plasticity, grey.
B
Using particle size distribution graph; sieve #200 60% pass and sieve #4 100% pass
Greater than 50% pass sieve #200 therefore first letter is M or C
Use Atterberg limits to determine suffix (used a hydrometer for soil B)
CL
CL, clay and silt with some sand, low to medium plasticity, brown.