Consistency Of Soil Flashcards
Rupture resistance is best described using
Stickiness and Plasticity
Describe the strength with which soil materials are held together
Consistency of soil
The ability of soil materials to change shape(but not volume), continuous under the influence of a constant pressure and to retain the impressed shape when the pressure is removed
Plasticity
Soil begins to stick to fingers but comes off one or the other cleanly; does not stretch when the fingers are opened
Slighty sticky
The ability of soil materials to adhere to other objects
Stickiness
Field test for stickiness
Non sticky
Slightly sticky
Sticky
Very sticky
The field measure of the ability of the soil to withstand pressure as applied using the thumb and forefinger
Rupture resistance
Separates inorganic clays from inorganic slits
A-line
When describing rupture resistance, we attempt to describe it using
Moist, Dry, and wet consistency
The resistance of soils to deformation and rupture
Consistency of soil
Water is added to soil to increase water content
Wet consistency
Soil sticks to both thumb and forefinger and tends to stretch a little and pull apart rather than pulling free from your finger
Sticky
Shrinkage limit, Plastic limit, and Liquid Limit are also known as
Atterberg limits
Atterberg limits were oberved by
Albert Mauritz Atterberg
Consistency can be described as
Dry, moist, and wet consistency
Atterberg limits were refined by
Arthur Casagrande
Soil sticks firmly to both thumb and forefinger and stretches when the fingers are opened
Very Sticky
Liquid Index ( LI)
LI = (w- PL) / ( LL-PL)
= (w-PL) / PI
The degree to which a reworked soil can be permanently deformed without rupturing
Plasticity of solids
Can undergo deformation without cracking
Plastic soil
No soil or practically no soil sticks to fingers
Non-sticky
Describes as the response of soil to physical change through (increasing) moisture content
Plasticity
Are basically the limits of water content used to define soil behavoir
Atterberg limits
Moisture content at which soil begins to behave as liquid material and begins to flow
Liquid limit
Moisture content at which soil begins to behave as plastic material
Plastic limit
Moisture content at which no futher volume change occurs further reduction in moisture content
Shrinkage limit
What lab apparatus is used to test liquid limit
Casagrande cup
After how many blows to reach the liquid limit
25
Specific Gravity
Gs = 1 / [( 1/SR) - (SL/100)]
The slope of the flow rate
Flow index
Flow index is equal to
FI = (w1 - w2) / log (N2/N1)
Another method to obtain the liquid limit
Fall cone test method
Is the moisture content at which the soil, when rolled into threads of 3.2mm (1/8 inch),crumbles
Plastic limit
PI =
PI = LL - PL
Indicates how much volume change is possible as changes above water content above the shrinkage limit occur
Shrinkage ratio
Is the moisture content of which the volume change of the soil mass ceases( or the volume no longer goes smaller)
Shrinkage limit
Is the upper limit of the relationship of the PI to the LL for any soil found so far
U-line
Is an index for identifying the swelling potential of clay soils
A = PI / u u = percent finer
Formula for change in moisture content
Change in moisture = density ( V1- V2) / m2
Shrinkage limit formula
SL = [(m1 -m2) / m2] -[(V1-V2)/ m2 ] density
Is themeasure of plasticity of the soil
Plasticity index
Provides the relative consistency of a cohesive soil with respect to the atterberg limits
Liquid Index ( LI )
Shrinkage ratio ( SR)
SR = density of dry / density of water
Commonly used to indicate the in situ denseness and loosenessof soil
Relative Density (Sr)
Relative Density is equal to
Dr = (emax -e) / (emax - emin)
Very loose, Dr is equal to
0-15
Loose, Dr is equal to
15-50
Medium, Dr is equal to
50-70
Dense, Dr is equal to
70-85
Very Dense, Dr is equal to
85-100
