Civil Engineering Reference
In-Depth Information
5.21 Table P5.21 shows the grain size distributions of two aggregates A
and B.
Table P5.21
Sieve Size, mm
25
19 12.5
9.5
4.750
2.36
1.18 0.600 0.300 0.150
0.075
% Passing Agg. A 100
92
76
71
53
38
32
17
10
5
3.0
% Passing Agg. B 100 100
92
65
37
31
30
29
28
21
15.4
Answer the following questions and show all calculations:
a. What are the maximum sizes of aggregates A and B?
b. Is aggregate A well graded? Why?
c. Is aggregate B well graded? Why?
5.22 Three aggregates are to be mixed together in the following ratio:
Aggregate A 20%
Aggregate B 45%
Aggregate C 35%
For each aggregate, the percent passing a set of five sieves is shown
in the following table:
Sieve Size (mm)
% Passing
% Passing
% Passing
Agg. A
Agg. B
Agg. C
9.5
85
50
40
4.75
70
35
30
0.6
35
20
5
0.3
25
13
1
0.15
17
7
0
Determine the percent passing each sieve for the blended aggregate.
5.23 Table P5.23 shows the grain size distribution for two aggregates and
the specification limits for an asphalt concrete. Determine the blend
proportion required to meet the specification and the gradations of
the blend. On a semilog gradation graph, plot the gradations of aggre-
gate A, aggregate B, the selected blend, and the specification limits.
Table P5.23
Percent Passing
Size
19 mm 12.5 mm 9.5 mm 4.75 mm 2.36 mm 0.60 mm 0.30 mm 0.15 mm 0.075 mm
(3/4 in.) (1/2 in.)
(3/8 in.)
(No. 4)
(No. 8)
(No. 30)
(No. 50)
(No. 100)
(No. 200)
Spec. limits
100
80-100
70-90
50-70
35-50
18-29
13-23
8-16
4-10
Aggregate A
100
85
55
20
2
0
0
0
0
Aggregate B
100
100
100
85
67
45
32
19
11
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