Civil Engineering Reference
In-Depth Information
T ABLE 5.6
Aggregate Grading Requirements for Superpave Hot Mix Asphalt
(AASHTO MP-2)
Sieve Size,
Nominal Maximum Size (mm)
mm (in.)
37.5
25
19
12.5
9.5
4.75
50 (2 in.)
100
—
—
—
—
—
37.5 (1 1/2 in.)
90-100
100
—
—
—
—
25 (1 in.)
90 max
90-100
100
—
—
—
19 (3/4 in.)
—
90 max
90-100
100
—
—
12.5 (1/2 in.)
—
—
90 max
90-100
100
100
9.5 (3/8 in.)
—
—
—
90 max
90-100
95-100
4.75 (No. 4)
—
—
—
—
90 max
90-100
2.36 (No. 8)
15-41
19-45
23-49
28-58
32-67
—
1.18 (No. 16)
—
—
—
—
—
30-60
0.075 (No. 200)
0.0-6.0
1.0-7.0
2.0-8.0
2.0-10.0
2.0-10.0
6.0-12.0
Generally, local agencies develop their own specifications for the gra-
dation of aggregates for asphalt concrete. Table 5.6 gives the aggregate grad-
ing requirements for Superpave hot mix asphalt (McGennis et al. 1995).
These specifications define the range of allowable gradations for asphalt
concrete for mix design purposes. Note that the percentage of material pass-
ing the 0.075-mm (No. 200) sieve, the fines or mineral filler, is carefully
controlled for asphalt concrete due to its significance to the properties of
the mix.
Once aggregate gradation from asphalt concrete mix design is estab-
lished for a project, the contractor must produce aggregates that fall within
a narrow band around the single gradation line established for developing
the mix design. For example, the Arizona Department of Transportation will
give the contractor full pay only if the gradation of the aggregates is within
the following limits with respect to the accepted mix design gradations:
Allowable Deviations
Sieve Size
for Full Pay
9.5 mm (3/8 in.) and larger
2.36 to 0.45 mm (No. 8 to No. 40)
0.075 mm (No. 200)
; 3%
; 2%
; 0.5%
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