ATTERBERG LIMITS AND SIEVE ANALYSIS Flashcards
boundary between the solid and semi-solid state
Shrinkage Limit
Boundary between the semi-solid and plastic state
Plastic Limit
boundary between the plastic and liquid state
Liquid Limit
plastic limit will be determined by rolling a soil paste into ____ diameter threads until it crumbles, and determining the moisture content.
3.2mm
“Atterberg Limits” is named after
the Swedish scientist Albert Mauritz Atterberg
Originally, six “limits of consistency” of fine-grained soils were defined by Albert Atterberg: the upper limit of viscous flow, the liquid limit, the sticky limit, the cohesion limit, the plastic limit, and the shrinkage limit. In current engineering usage, the term usually refers only to the liquid limit, plastic limit, and in some references, the shrinkage limit.
Atterberg Limits
the relative ease with which a soil can be deformed.
Consistency
the water content, in percent, of soil at the arbitrarily defined boundary between the semiliquid and plastic states.
Liquid Limit
the water content, in percent, of soil at the boundary between the plastic and semi-solid states.
Plastic Limit
a soil that has a range of water content over which it exhibits plasticity and which will retain its shape on drying.
Plastic Soil
the range of water content over which a soil behaves plastically. Numerically, it is the difference between the liquid and plastic limits.
Plasticity Index
Rotate the handle of the liquid limit device so that the cup lifts and drops at the rate of _______ drops per second.
1.9 to 2.1
is the difference between the liquid and plastic limits.
Plasticity Index
Roll the bass on the glass plate until it forms a thread about __ inches or ___mm in diameter.
⅛ inches or 3.2mm
ASTM used for LL and PL
(ASTM D 4318 - Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils)
The moisture content at which a standard cone of apex angle 30° and weight of 0.78 N (80 gf) will penetrate a distance d=20
mm in 5 seconds when allowed to drop from a position of point contact with the soil surface.
(BS 1377 - Fall Cone Method)
The number of blows required to achieve closure
varies between ________. The results are plotted on semi-logarithmic graph paper.
15 and 35
This method offers a more accurate method of determining the liquid and plastic limit;
Determination of Liquid Limit Using Fall Cone Method (BS 1377)
The moisture content, in percent, at which the volume of the soil mass ceases to change. (ASTM D427/ ASTM D4943)
Shrinkage Limit
What Soil Indices is indicated below?
0 - Non-plastic
1 – 5 Slightly plastic
5 – 10 Low plasticity
10 – 20 Medium plasticity
20 – 40 High plasticity
> 40 Very high plasticity
Plasticity Index Description
defines the relative consistency of a cohesive soil in the natural state
Liquidity Index
LI < 0 Semisolid
state
High strength; brittle; sudden
fracture is expected
0 < LI < 1 Plastic
state
Intermediate strength; soil
deformed like a plastic material
LI > 1 Liquid
state
Low strength; soil deforms like
a viscous fluid
TRUE
the numerical difference between the plastic limit and shrinkage limit of the remolded soil
Shrinkage Limit
- a valuable parameter for classifying the predominant minerals in the sediment
Activity of Clas; Ac
- the ratio of a given volume change expressed as a percentage of dry volume to the corresponding charge
in water content above the shrinkage limit expressed as a percentage of the weight of the oven-dried soil
Shrinkage Ratio
AC = PI/μ
Where μ - percent finer than 0.002 mm
Activity of Clay
Ac < 0.7 Inactive clay
0.7 < Ac < 1.2 Normal clay
Ac > 1.2 Active clay
TRUE
an indicator of the relative shear strength. As ___ increases, the firmness, or shear strength of the soil
also increases.
Consistency Index
the slope of the water content versus log10 of the blows number plot for the Casagrande cup method, is the
measure of the rate at which soil mass loses its shear strength with increased water content.
Flow Index
is the determination of the size range of particles present in the soil, expressed as a percentage of the total
dry weight.
Mechanical Analysis
Two methods are generally used to find the particle-size distribution of soil:
(1) sieve analysis
(2) hydrometer analysis
—for particle sizes larger than 0.075 mm in diameter and
Sieve Analysis
