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ICC (EC) Soils - Material Testing (Edit),
Combined 2025 Exam For Agriculture
Graded 100% A+ Score Questions And
Answers.
The strength of a soil, or the ability to compact a soil into a suitable construction material will depend on?
Soil type
Soil density
The amount of water in the soil
Types of soils
Gravel (mm to cm's in size)
Sand (mm in size)
Silt (fine particles with little cohesion)
Clay (has cohesion, can stick together)
Organic soils (peat, topsoil)
Organic soils (O)
Have a large componet of dead or decaying plants, and are not used in construction
Silt and Clay
Classified based on whether the soil is plastic (clay) or non-plastic (eg. can you roll it into a ball or string)
Gravel and Sand
are classified based on whether or not all the particles are roughly the same size (uniform, like a beach) or if there is a large variety in particle size (well-graded).
Soil layers
- (complex zone) 3 to 4m
- (glacio-lacustrine clay) 2-12m
- Glacial till, up to 9m in thickness
- Carbonate bedrock, the upper surface of which is often fractured, weathered and irrgular
Soil has two componets of strength
Cohesion (clay only)
Friction (when individual soil grains move across on another)
The three types of shear failure of soil are
general shear failure (bulging / tilting)
local shear failure (slight bulging)
Gravel ( >2 mm )
Sand ( 0.075 to 2 mm )
Silt ( 0.002 to 0.075 mm )
Clay ( <0.002 mm )
The particle size distribution of coarse-grained soils is typically determined by?
Mechanical sieve analysis
The particle size distribution of fine-grained soil is determined using a?
hydrometer analysis
Two parameters help to identify soils that are well-graded?
The Coefficient of Uniformity (Cu)
The Coefficient of Curvature (Cc)
The hydrometer analysis is used to determine the gradation of
slit and clay-sized particles.
Only soil particles passing the # 40 sieve (0.425) are used in the
hydrometer analysis
Hydrometer readings give us two things?
The specific gravity, or density, of the fluid tells us the % of material still in suspension.
The average downward velosity of the hydrometer can give us the diameter of the particle that is just coming out of solution.
The Swedish soil scientist, _____ , developed a method of quantitatively describing the effect of soil moisture on the consistency of fine-grained soils.
Albert Atterberg
Although Atterberg proposed five limits only the following three are in common useage today.
Liquid Limit
Plastic limit
Shrinkage limit
Only the Liquid Limit and Plastic Limit are normally used to?
classify soil plasticity
It is important to remember that all values related to the Atterberg limits are simply?
moisture content values
Atterberg Limits provide a means for classifying ___.
the plasticity of clay soil.
Plasticity is defined as
large deformations under constant stress with no change in volume.
The plasticity index (PI) is
the range of moisture contents over which the soil behaves as a plastic material.
Liquid Limit (LL) is
the moisture content above which soil behaves as a fluid.
Plastic Limit (PL) is
the moisture content below which the soil behaves as a plastic material
Shrinkage limit is
the moisture content below which the soil does not decrease in volume.
_____ is the most effective, economical, and widely used method of soil improvement and densification.
Compaction
The purpose of compaction is to
- lower soil permeability
- lower soil compressibility and minimize settlement
- increase the strength or bearing capacity of soils.
- improve resistance to erosion
Two compaction tests routinely carried out in the lab to obtain the maximum dry density and optimum moisture content of soils.
Standard Proctor test ( D 698 )
Modified Proctor test ( D 1557 )
Soil consists of
solid particles, air, and water
Types of weathering are
physical and chemical
Cobble _____ mm , _____ inch
60 to 200 , 3 to 12
Gravel _____ mm , _____ inch
2 to 60 ,
Sand _____ mm
0.075 mm to 2mm
Silt _____ mm
0.002 to 0.075 mm
Clay _____ mm
<0.002 mm
Coarse grained
cohesionless soils such as gravel and sand
Fine grained
Cohesive soils such as silt and clay
Organic solids contain
high natural organic content
Man-made
Created from human activities such as mineing, tiling, and landfill waste
What are the characteristics of gravel, sands and silts
cohesionless, non-plastic, and granular
What are the characteristics of clays
cohesive and plastic
What are the characteristics of organic soils
weak and deform excessively under load and should not be used as foundations
Landslides are a
type of slope failure or downward sediment
Particle Size Analysis is
Coarse Grained vs Fine Grained soils
Particle Size Curve Parameters
Effective particle size
Coefficient of Uniformity ( Cu )
Coefficient of Curvature ( Cc)
Defintion of well graded soil
Cu > 4 for gravel
Cu > 6 for sand
1 < Cc < 3 for gravel and sand
Noun - gravel, sand, silt, clay
35%
"and" gravel, and silt...
35%
adjective (ie gravelly, sandy, silty)
20 - 30%
"some" sand
10 - 20%
"trace"
1 - 10%
soil with 30% clay, 45% silt, 18% sand and 7% gravel
clayey silt, some sand, trace gravel
Void Ratio
e = Volume of voids / volume of soil
Porosity
n = Volume of voids / total volume
Yd = ( K1 x Pd ) = ( conversion constant x Dry Density )
unit weight (wet)
= weight total ( mass total * g ) / volume total
Moisture content
Mass of water / mass of solid
Specific Gravity
density of solid / density of water
Useful Relationship
e S = w G
p = [( Gs + eS ) / ( 1 + e )] / pwater
Set S =___ for psat
1
Set S = ____ for pdry
As e ___ density increases
decreases
As e _____ strength increases
decreases
As e ________ permeability
decreases
Cohesionless Soil ( gravel, sand )
Free running type of soil whose strength depends on friction between particles
Cohesive soil ( silt, clay )
Strength depends on surface tension for capillary water
Soil Classification
Is the arrangement of different soils with similar properties into groups that reflect soil physical and mechanical properties
D30^2 / ( D60 * D10 )
Well graded sand :
Cu > 6 and Cc = ( 1-3 ), otherwise, poorly graded
Well graded gravel :
Cu > 4 and Cc = ( 1-3 ), otherwise, poorly graded
Consistency of Cohesive Soil depends on :
Depends on the water content of the soil.
( At very low water contents, soil sample behaves like a solid )
( At very high water contents, may flow like a liquid)
soil water content, cohesive soil may be divided into 4 basic states :
- solid ( Dry )
- semi-solid ( Shrinkage Limit )
- plastic ( Plastic Limit )
- liquid ( Liquid Limit )
Plasticity Index ( PI )
PI = LL - PL
Liquid Limit Test ( LL )
The water content at which the soil will just close ( 0.5 in ) after 25 drops. ( WL for 25 drops )
Plastic Limit Test ( PL )
The water content at which soil crumbles when rolled into threads 3 mm ( 1/8 in ) in diameter.
Shrinkage Limit Test :
The water content of this sample if it is saturated with water at the same volume
GW
well graded gravel without fines (symbol)
GP
poorly graded gravel without fines (symbol)
SW
well graded sand without fines (symbol)
