ITEM 443 STONE MATRIX ASPHALT CONCRETE
443.01
443.02
443.03
443.04
443.05
443.06
443.07
443.08
443.09
Description
Quality Control Program
Composition
Mixing
Storage
Quality Control
Construction
Acceptance
Basis of Payment
443.01 Description. This work consists of constructing a stone matrix
asphalt concrete (SMA) course consisting of aggregate, asphalt binder,
and additives.
The requirements of 442 and 446 apply except as follows. Do not use
the warm mix asphalt method (402.09) for this item.
443.02 Quality Control Program. Update the Quality Control
Program meeting 403.03 to include a section for how the quality control,
production and placement of SMA will meet this specification. Submit
the revised program to the Laboratory with the SMA mix design to be
approved.
443.03 Composition. Discuss the mix design approach with the
Laboratory during the mix design and prior to submittal.
A. Design Limits. Submit a JMF to the Laboratory which meets the
requirements of Table 443.03.1 and Table 443.03-2.
TABLE 443.03-1 MIX GRADATION
Sieve
3/4 inch (19.0 mm) sieve
1/2 inch (12.5 mm) sieve
3/8 inch (9.5 mm) sieve
No. 4 (4.75 mm) sieve
No. 8 (2.36 mm) sieve
No. 50 (300 µm) sieve
No. 200 (75 µm) sieve
Total Percent Passing
100
85 to 100
50 to 75
20 to 28
15 to 24
10 to 20
8 to 12
TABLE 443.03-2 MIX PROPERTIES
Property Description
Binder, % (1)
VMA, % (2)
Draindown Test, % (3)
Design Air Voids, %
Design Gyrations (4)
VCA MIX / VCA DRC (5)
TSR (6)
F/A
Specification
5.8 to 7.5
16.0 to 19.0
0.3
3.5
65
< 1.0
0.80
NA
(1)
by total mix
(2)
based on bulk gravity
(3)
AASHTO T305 conducted at mix production temperature (not compaction
temperature)
(4)
Nini and Nmax do not apply
(5)
VCA = Volume of Coarse Aggregate (Calculated for mix and dry rodded
conditions per AASHTO PP41- 02 or newer version.)
(6)
Unconditioned specimens will have a minimum 65 psi (450 kPa) retained
strength.
Compact specimens at 300 ºF (149 ºC) for PG 70-22M and 310 ºF
(154 ºC) for PG 76-22M.
B. Asphalt Binder. Provide asphalt binder conforming to 702.01.
C. Coarse Aggregate. Use approved coarse aggregates. Ensure
coarse aggregates meet 703.05 and Table 443.03-3.
TABLE 443.03-3 AGGREGATE REQUIREMENTS
Tests
ASTM
D 4791
ASTM D 5821
AASHTO T 96
Description
% Flat & Elongated Ratio at
3:1, (max. to min.),
5:1, (max. to min.)
% Crushed, one / two faces
LA Abrasion (stone or gravel)
Specification
20 max
5 max
100 / 90 min
35 max
D. Mineral Filler. Conform to 703.07. Use mineral filler in the JMF
with a plasticity index (AASHTO T 90) not greater than 4 (does not
apply to hydrated lime). Reclaimed asphalt concrete pavement passing
the 5/8 inch (16 mm) sieve may be used as filler only. Do not account
for reclaimed asphalt concrete pavement binder content. Do not use
quicklime (CaO). Do not premix filler with another aggregate. Cover
mineral filler piles to protect from rain.
Blend the mineral filler, asphalt binder and fiber stabilizer into a
homogenous mixture and test the mortar for the following properties of
Table 443.03-4.
TABLE 443.03-4 MORTAR TEST REQUIREMENTS
Tests
AASHTO TP5-98
AASHTO TP5-98, T24097
AASHTO TP1-98, PP198
Description
Specification
5 minimum
11 minimum
(kPa)
PAV Aged BBR, Stiffness
(Mpa)
1500 maximum
E. Reclaimed Asphalt Concrete Pavement. Do not use reclaimed
asphalt concrete pavement except as described in D above.
F. Fiber Stabilizer. Choose and meet the requirements of one of the
following fiber stabilizers. Submit with the JMF submittal the fiber
manufacturer’s most recent actual test data and a certification of
compliance for the fiber type to be used. Protect the fiber stabilizer from
moisture or other contamination.
Cellulose Fibers. Add the fiber at a dosage rate of 0.3 - 0.4% by
weight of the total mix as directed by the Engineer to control draindown
in production.
Property Description
1. Fiber length (max):
2. Sieve Analysis - Alpine Sieve Method
Passing No. 100 (150 µm) sieve
Sieve Analysis - Ro-Tap Sieve Method
Passing No. 20 (850 µm) sieve:
Passing No. 40 (425 µm) sieve:
Passing No. 100 (150 µm) sieve:
3. Ash Content:
4. pH:
5. Oil Absorption:(times fiber weight)
6. Moisture Content (max):
Specification
0.25 inch (6.35 mm)
60-80%
80-95%
45-85%
5-40%
18% non-
5.0%
Cellulose Pellets. Cellulose pellets consist of cellulose fiber and may
be blended with 0 - 20% asphalt binder. Meet the cellulose fiber
requirements above. If no asphalt binder is used, add the pellet at a
dosage rate of 0.3 - 0.4% by weight of the total mix as directed by the
Engineer to control draindown in production. Adjust the fiber dosage to
maintain the desired fiber amount when fiber is pre-blended with binder.
1. Pellet size:
1/4 cubic inch (maximum)
2. Binder:
25 - 80 pen.
Mineral Fiber. Use mineral fibers made from virgin basalt, diabase,
or slag treated with a cationic sizing agent to enhance disbursement of the
fiber as well as increase adhesion of the binder to the fiber surface. Add
the fiber at a dosage rate of 0.3 - 0.4% by weight of the total mix as
directed by the Engineer to control draindown in production.
1. Average Fiber length (max): 0.25 inches (6.35mm)
Average Fiber thickness (max) : 0.0002 inches(0.005mm)
2. Shot content (ASTM C612)
Passing No. 60 (250 µm) sieve:
90 - 100%
Passing No. 230 (63 µm) sieve:
65 - 100%
3. Degradation (max)*:
30%
* (GeorgiaDOT-124/McNett ) - copy available from the Office of
Materials Management, Asphalt section.
443.04 Mixing. Conform to the following additional requirements.
A.
Fiber Stabilizer.
Furnish feeder equipment specifically
manufactured to uniformly feed fiber into the plant and that is automated
through connection with plant controls. Include a low level and no-flow
indicator and print out the feed rate of the feeder supply system and
include a transparent pipe section for observing flow consistency. The
Engineer will approve the fiber feed system by a trial load of SMA and
inspection of the bag house collected material prior to the start of
production. Conduct and document a weekly quick check of the fiber
feed calibration according to the Quality Control Plan. Conduct a daily
check of fiber usage by calculating and documenting on the TE 199 that
fiber usage is within 10% of the intended usage.
In drum plants, add the fibers in loose form, by an automated
calibrated feed system, such that the fibers are coated by asphalt binder
before being caught in the drum air flow.
In batch plants, distribute the fiber uniformly before injecting asphalt
binder and increase mixing time a minimum of 5 seconds.
B. Mineral Filler. Filler may be fed through a hopper if consistency
of flow is achieved. If a problem in feeding consistency occurs a
pneumatic system will be required. Feed filler into the weigh hopper or
pug mill of a batch plant, or at a point away from the flame on a drum
plant.
443.05 Storage. Do not store the SMA at the plant for more than 2
hours. Do not exceed a mix temperature of 350 ºF (180 ºC). Provide
SMA at a minimum of 300 ºF (148 ºC) when it arrives at the paver,
unless otherwise approved by the Laboratory. If draindown occurs
shorten the storage time and increase the fiber dosage.
443.06 Quality Control. Ensure an employee of the Contractor with
a Level 3 rating is at the plant or construction site during production of
the SMA for any test strips and through at least one full production day
satisfactory to the District.
Perform quality control tests every 3 hours of production. The
increased frequency of quality control testing may require additional
quality control personnel at the plant. Determine the asphalt binder
content, gradation, moisture content, air voids, VMA, and MSG of the
SMA. For each test series calculate the VCAMIX / VCADRC. If the
limit of 1.0 is exceeded stop production until resolved. Perform a
draindown test once each day of production and raise fiber dosage 0.1%
if the test limit is exceeded. Do not exceed the No. 200 (75 µm) sieve
design bands by the moving average of three tests. Compact specimens
at 300 ºF (149 ºC) for PG 70-22M and 310 ºF (154 ºC) for PG 76-22M.
Due to sample variability with SMA, a larger than usual sample size from
which material is obtained for the various tests is required.
443.07 Construction. At least 24 hours prior to beginning a test strip
meet with the Engineer and DET and provide a written summary of steps
taken to assure mix quality and construction practices account for the
special needs of SMA production and placement. Send a copy of the
written summary to the Laboratory.
A. Test Strips and JMF Adjustment. Do not begin full production of
the SMA until receiving authorization from the District.
This
authorization will be based on the successful construction of one or more
test strips. Test strips consist of 50 to 100 tons of SMA produced and
placed in accordance with these specifications. Cease SMA production
that day unless another test strip is needed. Place test strips in one
continuous mat. The test strip will be included in the first lot for
determining density for payment. Test strips are incidental to the pay
item.
During the construction of a test strip, perform 1 set of quality control
tests as described above and obtain and test 3 random cores of the
compacted pavement. Within 1 working day after a test strip is
completed, the District, the Laboratory and the Contractor's Level 3
employee will determine if any changes in the SMA JMF, production, or
placement procedures are needed. A redesign of the JMF or another test
strip may be required. The Laboratory will notify the District of any JMF
adjustments. Do not start production until notified by the District.
B. Compaction. Start compaction immediately after the SMA has
been placed by the paver. Use only steel wheel rollers. Vibratory rollers
in vibratory mode, set at a high frequency and low amplitude, can be
used as the breakdown roller only. Always operate the breakdown roller
immediately behind the paver. If isolated, small fat spots develop, apply
sand immediately during compaction. If continuous and/or large fat
spots develop, cease production until resolved. Do not compact SMA
that is below 230 ºF (110 ºC).
C. Hauling. Do not allow trucks to dump any mix on the project mat
after delivering mix to the paver. Provide a suitable place for bed
cleaning off of the mat.
443.08 Acceptance. After accepting the test strips, the Department
will accept SMA according to 446.05.
443.09 Basis of Payment. The Department will pay for accepted
quantities of Stone Matrix Asphalt Concrete, complete in place, including
test strip, at the contract price as modified by 446.05, as follows:
Item
Unit
Description
443
Cubic Yard
(cubic Meter)
Cubic Yard
(cubic Meter)
Stone matrix asphalt concrete,
12.5mm, PG70-22M, (446)
Stone matrix asphalt concrete,
12.5mm, PG76-22M, (446)
443