Environmental Engineering Reference
In-Depth Information
Gravels: more than one half retained on no. 4 sieve (3/16 in.)
●
Sands: more than one half passing no. 4 sieve
Fine-grained soils: more than onehalf passing no. 200 sieve
●
Low plasticity: LL
50 (includes organic clays and silts)
●
High plasticity: LL
50 (includes organic clays and silts)
●
Highly organic soils
Subdivisions are based on laboratory test results.
TABLE 5.35
Identification of Composite Clay Soils on an Overall Plasticity Basis
a
Degree of
PI
Identification
Smaller Diameter of
Overall Plasticity
(Burmister System)
Rolled Threads, mm
Nonplastic
0
SILT
None
Slight
1-5
Clayey Silt
6
Low
5-10
SILT and CLAY
3
Medium
10-20
CLAY and SILT
1.5
High
20-40
Silty CLAY
0.8
Very high
40
CLAY
0.4
a
After Burmister, D.M., 1951. Reprinted with permission from the
Annual Book of ASTM Standards
, Part 19,
Copyright. Reprinted with permission.
Descriptive
terms
Trace
3
1-1/2 3/4
3/8
4
8
16
30
50
100 200 Sieves
100
90
80
70
60
50
40
30
20
10
0
10
Little
20
Some
AH-5
35
And
And
50
AH-3
and
35
Some
20
Little
10
0
Trace
200
60
20
6
2
0.6
0.2
0.06
0.02
0.006
0.002
Grain size (mm)
Boulders
cobbles
Gravel
M
Sand
MF
C Silt
−
nonplastic, cohesionless
Clay-soil
−
plasticity and clay-qualities
C
F
C
228
9 in.
76.2
3 in.
25.4
1 in.
9.52
3/8 in.
2.0
Nos. 10
0.59
30
0.25
60
0.074
200
mm
Sieves
Sample AH-3
Long Island, NY
Depth 1 to 3 ft
Identification: Light gray medium to fine gravel, and coarse to medium sand (Symbol form
−
lg m +fG, a
.
cmS)
Gravel
−
water-worn, sand
−
subangular
Sample AH-5
Long Island, NY
Depth 0 to 2 ft
Identification: Gray medium to fine sand
−
beach sand (Symbol form
−
g mfS)
Few shell fragments
FIGURE 5.14
Gradation curves constructed from field identifications. Curve characteristics may be used for estimating
maximum and minimum densities of
k
and
if
D
R
is known (see
Section 3.2.3
discussion of soil gradation).
(From Burmister, D.M., ASTM Vol. 48, American Society for Testing and Materials, Philadelphia, PA, 1951.
Copyright ASTM International. Reprinted with permission.)
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