Aggregate Gradation and Sampling
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Aggregate Gradation
Gradation Analysis
percent coarser
or
percent retained
percent finer
or
percent pas sin g
CIVL 3137
Percentages
are calculated
by mass
38
Gradation Chart
Percent Passing
100
80
60
Total mass percent passing each sieve
40
20
0
Opening Size (mm)
CIVL 3137
39
Gradation Chart
Percent Passing
100
80
60
Total mass percent passing each sieve
40
20
0
Opening Size (mm)
CIVL 3137
40
Sieves
CIVL 3137
41
Shakers
Gilson Shaker
CIVL 3137
Mary Ann Shaker
42
Sieve Sizes
CIVL 3137
43
Gradation Chart
1½" ¾"
Percent Passing (%)
100
3/ "
8
4
8
16
30
50
100 200
80
60
40
20
0
100
10
1
0.1
0.01
Opening Size (mm)
CIVL 3137
47
Gradation Example 1
Gradation Example 2
Uniformly Graded Aggregate
1½" ¾"
Percent Passing
100
3/ "
8
4
8
16
80
30
50
100 200
Uniformly
graded
sand
60
Uniformly
graded
gravel
40
20
0
100
10
1
0.1
0.01
Opening Size (mm)
CIVL 3137
50
Uniformly Graded Aggregate
Narrow range of sizes
Grain-to-grain contact
High void content
High permeability
Low stability
Difficult to compact
CIVL 3137
51
Open-Graded Aggregate
1½" ¾"
Percent Passing
100
3/ "
8
4
8
16
30
50
100 200
Open
graded
sand
80
60
Open
graded
gravel
40
20
0
100
10
1
0.1
0.01
Opening Size (mm)
CIVL 3137
52
Open-Graded Aggregate
Few fine particles
Grain-to-grain contact
High void content
High permeability
High stability
Difficult to compact
CIVL 3137
53
screenings
CIVL 3137
54
Gap-Graded Aggregate
1½" ¾"
Percent Passing
100
3/ "
8
4
8
16
30
50
100 200
Open
graded
sand
80
60
Gap
graded
blend
Open
graded
gravel
40
20
0
100
10
1
0.1
0.01
Opening Size (mm)
CIVL 3137
55
Gap-Graded Aggregate
Missing middle sizes
No grain-to-grain contact
Moderate void content
Moderate permeability
Low stability
Easy to compact
CIVL 3137
56
Dense-Graded Aggregate
1½" ¾"
Percent Passing
100
3/ "
8
4
8
16
30
50
100 200
80
60
40
Dense
graded
gravel
20
0
100
10
1
0.1
0.01
Opening Size (mm)
CIVL 3137
57
Dense-Graded Aggregate
Wide range of sizes
Grain-to-grain contact
Low void content
Low permeability
High stability
Difficult to compact
CIVL 3137
58
Fuller’s Curve
Fuller, W.B. and Thompson, S.E. “The laws of
proportioning concrete," Transactions of the
ASCE, v. 159, 1907.
di
pi
D
CIVL 3137
0.50
pi = percent passing ith sieve
di = opening size of ith sieve
D = maximum particle size
59
CIVL 3137
60
Maximum Density Curve
In 1962 FHWA published a modified version of
Fuller’s equation with a different exponent.
di
pi
D
CIVL 3137
0.45
0.50
pi = percent passing ith sieve
di = opening size of ith sieve
D = maximum particle size
61
CIVL 3137
62
Dense-Graded Aggregate
1½" ¾"
Percent Passing
100
3/ "
8
4
8
16
30
50
100 200
80
TDOT 411-D
60
Maximum
Density
Curve for
½" NMAS
40
20
0
100
10
1
0.1
0.01
Opening Size (mm)
CIVL 3137
65
Dense-Graded Aggregate
200
Percent Passing
100
30
8
4
3/ "
8
1/ " 5/ "
2
8
¾"
80
TDOT 411-D
60
Maximum
Density
Curve for
½“ NMAS
40
20
0
0
1
2
3
4
5
Opening Size (mm) Raised to the 0.45 Power
CIVL 3137
66
