Item 442 Superpave Asphalt Concrete
442.01
Description
442.02 Type A Mix Design
442.03 Type B
Mix Design
442.04 Asphalt
Binder
442.05 Quality
Control
442.06
Compaction
442.07
Acceptance
442.08 Basis of
Payment
442.01 Description. This work
consists of gyratory mix design, material, and quality control requirements for
constructing a Superpave asphalt concrete pavement
surface or intermediate course. The asphalt concrete pavement course
consists of aggregate, and asphalt binder mixed in a central plant and spread
and compacted on a prepared surface.
The
requirements of Item 441 apply, except as modified by
this specification.
442.02 Type A Mix Design. Design
the mixture composition for a Type A mix according to 441.02
and the most recent Asphalt
Institute Superpave Mix Design Manual (SP-2) for design procedures and
material properties except as modified by this subsection. Include in the
JMF submittal the standard Department cover and
summary page; all printouts from the gyratory compactor (all gyratory points
not necessary); and analysis covering the required mix properties. Submit
one compacted gyratory sample and loose mix for compaction of another sample,
in addition to a 5-pound (2000 g) loose sample, for each JMF.
The
Contractor may use the Marshall flow test in design as
an indicator of potential for excess tenderness.
Supply
aggregate according to the lane current average daily truck traffic (Lane ADTT) as follows unless otherwise shown on the plans:
Lane ADTT = Current ADT × T24 × 0.45
Where:
Current ADT = current average daily traffic
count from the plans
T24 =
percent trucks per day from the plans
Table
442.02-1 Gyration Level and Material
Requirements
Lane ADTT |
Nini |
Ndes |
Nmax |
Coarse Aggregate Angularity |
Fine Aggregate Angularity |
Flat and Elongated Particles |
Sand Equivalent |
<4000 |
7 |
65 |
105 |
95 [1] /90 [2] |
44 |
10 |
45 |
>4000 |
7 |
65 |
105 |
100 [1] /100 [2] |
44 |
10 |
50 |
[1]
Percent fractured (one or more faces) according to ASTM D5821
[2]
Percent fractured (two or more faces) according to ASTM D5821
Submit
aggregate to be used to the Laboratory for approval a minimum of 3 weeks before
submitting a JMF for approval.
If
fine aggregate is from crushed carbonate stone or air-cooled blast furnace
slag, the Department will not require the fine aggregate angularity (FAA)
test. The Department will allow a blend of a material not meeting the FAA
with a material that meets the FAA, but calculate the FAA result based on the
individual Department FAA results and actual blend percentages. Obtain
Department approval of any blends.
The
restricted zone does not apply. Use control points according to SP-2,
except as specified in Table 442.02-2.
Table
442.02-2 Aggregate Gradation Requirements
Sieve Size |
9.5 mm mix |
12.5 mm mix |
19 mm mix |
|
Total Percent Passing |
||||
1 1/2 inch |
(3.75 mm) |
– |
– |
100 |
3/4 inch |
(19 mm) |
– |
100 |
85 to 100 |
1/2 inch |
(12.5 mm) |
100 |
95 to 100 |
90 max |
3/8 inch |
(9.5 mm) |
90 to 100 |
96 max |
– |
No. 4 |
(4.75 mm) |
70 max |
52 min |
– |
No. 8 |
(2.36 mm) |
34 to 52 |
34 to 45 |
28 to 45 |
No. 200 |
(75 µm) |
2 to 8 |
2 to 8 |
2 to 6 |
Ensure that the
F/A ratio is a maximum of 1.2. Use a 2-hour cure
for the mix design .
If more than 15
percent fine aggregate not meeting FAA is used, perform a loaded wheel test (LWT) according to Supplement
1057. To estimate a LWT sample mix volume,
use the bulk density from gyratory specimens at Ndes.
Results less than 0.20 inch (5.0 mm) at 120 °F (49 °C) are
considered passing.
The
Contractor may use reclaimed asphalt concrete pavement according to 401.04. Test design volumetric properties at Ndes. Test Nmax
for the required criteria. Ensure that the VMA
is not less than the minimum values of Table 442.02-3.
Mix |
VMA (percent minimum) |
9.5 mm |
15 |
12.5 mm |
14 |
19.0 mm |
13 |
442.03 Type B Mix Design. Apply the
mix design specified in 442.02 for a Type A mix except
as modified by this subsection:
Modify
the Coarse Aggregate Angularity of Table 442.02-1
according to Table 442.03-1.
Lane ADTT |
Coarse Aggregate Angularity |
<4000 |
65 [1] /65 [2] |
>4000 |
75 [1] /70 [2] |
[1] Percent fractured (one or more faces) according
to ASTM D5821 [2] Percent fractured (two or more faces) according
to ASTM D5821 |
Ensure
that at least 50 percent by weight of virgin fine aggregate is aggregate
meeting FAA or is crushed carbonate stone or air-cooled blast furnace
slag. Modify the No. 8 (2.36 mm) sieve requirement for a 12.5 mm mix in
Table 442.02-2 to 34 to 40 percent.
Apply an F-T value of +2 according to 441.02 and
441.09.
442.04 Asphalt Binder. Use a PG 70-22M asphalt
binder for surface courses and a PG 64-28 asphalt binder for intermediate
courses.
The
minimum total asphalt binder content for a surface course is 5.7 percent.
442.05 Quality Control. Conform to 441.09, except as specified in this
subsection. Ensure that plant operation and quality control testing
conform to the Contractor’s Quality Control Program (QCP).
Use
a gyratory compactor conforming to the requirements of Superpave. If the gyratory compactor was moved to
the plant before production, calibrate it and present the results to the
DET.
Determine
bulk gravity for air voids determination on specimens compacted to Ndes. Once each day for the first 3
production days compact one set of specimens to Nmax.
Ensure that density at Nmax is
less than 98.0 percent of MSG. The Department will not allow production
to continue if Nmax is greater than or
equal to 98.0 percent of MSG unless acceptable corrections and retest are made.
If
the design gradation requires an LWT test, take a
sample sufficient to run a LWT test
once each day for the first 3 days and test it according to Supplement
1057. The Contractor may perform the LWT
test in the Contractor’s Level 2 laboratory, but must compact the sample the
same day the sample was taken, cure it overnight, and test it the following
day. Give the test result and sample density to the DET
the day of the LWT test. Report the LWT data on the Quality Control Report.
442.06 Compaction. Cease production if compaction
causes bumps in the mix or the mix is excessively tender.
442.07 Acceptance. The Department will base
acceptance of the asphalt concrete mix on the item specified in the Contract
(i.e., Item 446, Item 448).
442.08 Basis of Payment. The Department will pay
for accepted quantities at the contract prices as follows:
Item
Unit
Description
442
Cubic
Yard
Asphalt Concrete Surface
(Cubic
Meter)
Course, 12.5 mm, Type A (446)
442
Cubic
Yard
Asphalt Concrete Surface
(Cubic
Meter)
Course, 12.5 mm, Type B (446)
442
Cubic
Yard
Asphalt Concrete Surface
(Cubic
Meter)
Course, 9.5 mm, Type A (446)
442
Cubic
Yard
Asphalt Concrete Surface
(Cubic
Meter)
Course, 9.5 mm, Type B (446)
442
Cubic
Yard
Asphalt Concrete Intermediate
(Cubic
Meter)
Course, 19 mm, Type A (446)
442
Cubic
Yard
Asphalt Concrete Intermediate
(Cubic
Meter)
Course, 19 mm, Type B (446)
442
Cubic
Yard
Asphalt Concrete Intermediate
(Cubic
Meter)
Course, 9.5 mm, Type A (448)
442
Cubic
Yard
Asphalt Concrete Intermediate
(Cubic Meter)
Course, 9.5 mm, Type B (448)
442
Cubic
Yard
Asphalt Concrete Surface
(Cubic
Meter)
Course, 12.5 mm, Type A (448)
442
Cubic
Yard
Asphalt Concrete Surface
(Cubic
Meter)
Course, 12.5 mm, Type B (448)
442
Cubic
Yard
Asphalt Concrete Surface
(Cubic
Meter)
Course, 9.5 mm, Type A (448)
442
Cubic
Yard
Asphalt Concrete Surface
(Cubic
Meter)
Course, 9.5 mm, Type B (448)
442
Cubic
Yard
Asphalt Concrete Intermediate
(Cubic
Meter)
Course 19 mm, Type A (448)
442
Cubic
Yard
Asphalt Concrete Intermediate
(Cubic
Meter)
Course, 19 mm, Type B (448)