ITEM 443 STONE MATRIX ASPHALT CONCRETE

443.01 Description

443.02 Quality Control Program

443.03 Composition

443.04 Mixing

443.05 Storage

443.06 Quality Control

443.07 Construction

443.08 Acceptance

443.09 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.

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

Total Percent Passing

3/4 inch (19.0 mm) sieve

100

inch (12.5 mm) sieve

85 to 100

3/8 inch (9.5 mm) sieve

50 to 75

No. 4 (4.75 mm) sieve

20 to 28

No. 8 (2.36 mm) sieve

15 to 24

No. 50 (300 m) sieve

10 to 20

No. 200 (75 m) sieve

8 to 12

TABLE 443.03-2 MIX PROPERTIES

Property Description

Specification

Binder, % (1)

5.8 to 7.5

VMA, % (2)

16.0 to 19.0

Draindown Test, % (3)

0.3

Design Air Voids, %

3.5

Design Gyrations (4)

65

VCA MIX / VCA DRC (5)

< 1.0

TSR (6)

0.80

F/A

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 300F (149C) for PG 70-22M and 310F (154C) for PG 76-22M.

B. AsphaltBinder. 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

Description

Specification

ASTM

D 4791

% Flat & Elongated Ratio at

3:1, (max. to min.),

5:1, (max. to min.)

 

20 max

5 max

ASTM D 5821

% Crushed, one / two faces

100 / 90 min

AASHTO T 96

LA Abrasion (stone or gravel)

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 (16mm) sieve may be used as filler only. Do not account for RAP 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

Description

Specification

AASHTO TP5-98

Unaged DSR, G*/ sin (kPa)

5 minimum

AASHTO TP5-98, T240-97

RTFO Aged DSR, G*/ sin (kPa)

11 minimum

AASHTO TP1-98, PP1-98

PAV Aged BBR, Stiffness (Mpa)

1500 maximum

E. Reclaimed AsphaltConcretePavement. Do not use reclaimed asphalt concrete pavement except as described in C above.

F. Fiber Stabilizer. Choose and meet the requirements of one of the following fiber stabilizers. Submit with the JMF submittal the fiber manufacturers 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 Engineerto control draindown in production.

Property Description

Specification

1. Fiber length (max):

0.25 inch (6.35 mm)

2. Sieve Analysis - Alpine Sieve Method

 

Passing No. 100 (150m) sieve

60-80%

Sieve Analysis - Ro-Tap Sieve Method

 

Passing No. 20 (850 m)sieve:

80-95%

Passing No. 40 (425 m) sieve:

45-85%

Passing No. 100 (150 m) sieve:

5-40%

3. Ash Content:

18% non-volatiles (5%)

4. pH:

7.5 (1.0)

5. Oil Absorption:(times fiber weight)

5.0 (1.0)

6. Moisture Content (max):

5.0%

 

Cellulose Pellets. Cellulose pellets will 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 Engineerto 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 Engineerto 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 m) sieve: 90 - 100%

Passing No. 230 (63 m)sieve: 65 - 100%

3. Degradation (max)*: 30%

* (GeorgiaDOT-124/McNett ) - copy available from the Office of Materials Management, Asphaltsection.

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 Engineerwill 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 per 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 thru 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 pugmill 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 350F (180C). Provide SMA at a minimum of 300F(148C) 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. An employee of the Contractorwith a Level 2 rating will be 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 m) sieve design bands by the moving average of three tests. Compact specimens at 300F (149C) for PG 70-22M and 310F (154C) 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 Engineerand 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 above 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 will consist of 50 to 100 tons of SMA produced and placed in accordance with these specifications. No further SMA production will occur that day unless another test strip is needed. A test strip will be 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 2 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 230F (110C).

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 procedures except use the table 443.08-1,

TABLE 443.08 -1

Mean of Cores[1]

Pay Factor

98.0% or greater

[2]

97.0 to 97.9%

0.94

96.0 to 96.9%

1.00

94.0 to 95.9%

1.04

93.0 to 93.9%

1.00

92.0 to 92.9%

0.98

91.0 to 91.9%

0.90

90.0 to 90.9%

0.80

89.0 to 89.9%

[3]

Less than 89.0%

[2]

[1] Mean of cores as percent of average MSG for the production day.

[2] For surface courses, remove and replace. For other courses, the District will determine whether the material may remain in place. If the District determines the course should be removed and replaced, the Contractorshall remove and replace this course and all courses paved on this course. The pay factor for material allowed to remain in place is 0.60.

[3] The District will determine whether the material may remain in place. If the District determines the course should be removed and replaced, the Contractorshall remove and replace this course and all courses paved on this course. The pay factor for such material allowed to remain in place is 0.70.

 

443.09 Basis of Payment. The Department will pay for accepted quantities of Stone Matrix AsphaltConcrete, complete in place, including test strip, at the contract price as modified above.

Item unit Description

443 Cubic Yard Stone matrix asphalt

(cubic Meter) concrete, 12.5mm, PG70-22M, (446)

443 Cubic Yard Stone matrix asphalt

(cubic Meter) concrete, 12.5mm , PG76-22M, (446)