Civil Engineering Reference
In-Depth Information
9.21 For asphalt concrete, define
a. air voids
b. voids in the mineral aggregate
c. voids filled with asphalt
9.22 An aggregate blend is composed of 53% coarse aggregate by weight
(Sp. Gr. 2.702), 43% fine aggregate (Sp. Gr. 2.621), and 4% filler (Sp.
Gr. 2.779). The compacted specimen contains 6% asphalt binder (Sp.
Gr. 1.052) by weight of total mix, and has a bulk density of
Ignoring absorption, compute the percent voids in total mix, percent
voids in mineral aggregate, and the percent voids filled with asphalt.
9.23 An asphalt concrete mixture includes 94% aggregate by weight. The
specific gravities of aggregate and asphalt are 2.7 and 1.0, respectively.
If the bulk density of the mix is 145 pcf, what is the percent voids in
the total mix?
9.24 After two years of traffic, cores were recovered from the roadway
which has severe rutting and bleeding. The bulk specific gravity and
the maximum theoretical specific gravity were measured on these
cores and are as follows:
Bulk specific
Maximum theoretical specific
a. Calculate the air voids
b. If the design air void content was 4%, explain what effect the cal-
culated air voids had on the rutting and bleeding noted.
9.25 An asphalt concrete specimen has the following properties:
Asphalt by total weight of mix
Bulk specific gravity of the
Theoretical maximum specific
Bulk specific gravity of
Calculate the percents VTM, VMA, and VFA.
9.26 Briefly describe the volumetric mix design procedure of Superpave.
9.27 Based on the data shown in Table P9.27, select the blend for a Su-
perpave design aggregate structure.
145.2 lb/ft
3
.
gravity
=
2.498
gravity
=
2.545
content
=
5.3%
mix
=
2.442
gravity
=
2.535
aggregate
=
2.703
Table P9.27
Blend
Data
1
2
3
G
mb
2.451
2.465
2.467
G
mm
2.585
2.654
2.584
G
b
1.030
1.030
1.030
P
b
5.9
5.5
5.8
P
s
94.1
94.5
94.2
P
d
4.5
4.5
4.5
G
sb
2.657
2.667
2.705
H
ini
127
135
124
H
des
113
114
118
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