ITEM 443 STONE MATRIX ASPHALT CONCRETE
443.01 Description. This work consists of design, production, placement, compaction and
testing of one or more courses of stone matrix asphalt concrete (SMA), on a prepared foundation. The aggregate and asphalt binder are mixed in a central plant then spread and compacted on the prepared surface. The requirements of 401, 402, 403, 440, 442; and 446 or 447 apply with the additional requirements of this specification. Do not use the warm mix asphalt method (402.05) for this item.
443.02 Quality Control Program. With the submission of a SMA mix design to be approved,
submit to OMM a revised Quality Control Program, if necessary, to include a section to satisfy
403.03 P.
443.03 Composition. Discuss the mix design approach with OMM during the mix design process
and prior to submittal.
A.Design Limits. Submit a JMF to the Laboratory which meets the requirements of Table 443.03.1. TABLE 443.03-1 MIX COMPOSITION Property Description Specification 3/4 inch (19.0 mm) [1] 100 1/2 inch (12.5 mm) [1] 85 to 100 3/8 inch (9.5 mm) [1] 50 to 75 No. 4 (4.75 μm0 [1] 20 to 28 No. 8 (2.36 μm) [1] 15 to 24 No. 50 (300 μm) [1] 10 to 20 No. 200 (75 μm) [1] 8 to 12 Binder, % [2] 5.8 to 7.5 VMA, % [3] 16.0 to 19.0 Draindown Test, % [4] 0.3 Design Air Voids, % 3.5 Design Gyrations [5] 65 VCA MIX / VCA DRC [6] < 1.0 TSR [7] 0.80 F/A NA [1] Sieve, percent passing [2] By total mix [3] Based on bulk gravity [4] AASHTO T305 conducted at mix production temperature (not compaction temperature) [5] Nini and Nmax do not apply [6] VCA = Volume of Coarse Aggregate (Calculated for mix and dry rodded conditions according to AASHTO R46.) [7] Unconditioned specimens will have a minimum 65 psi (450 kPa) retained strength.. Compact specimens at 300 °F (149 °C) for PG 70-22M and 310 °F (154 °C) for PG 76-22M..
B.Coarse Aggregate. Use approved coarse aggregates. Ensure coarse aggregates meet 703.05 and Table 443.03-2. TABLE 443.03-2 AGGREGATE REQUIREMENTS Tests Description Specification ASTM D4791 % Flat and Elongated Ratio at 3:1, (max. to min.) 5:1, (max. to min.) 20 max 5 max ASTM D5821 % Crushed, one / two faces 100 / 90 min AASHTO T 96 LA Abrasion (stone or gravel) 35 max
C.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 443.03-3. TABLE 443.03-3 MORTAR TEST REQUIREMENTS Tests Description Specification AASHTO T315 Unaged Dynamic Shear Rheometer, G*/ sin (kPa) 5 minimum AASHTO T315 & T240 RTFO Aged Dynamic Shear Rheometer, G*/ sin (kPa) 11 minimum AASHTO R28 & T313 PAV Aged BBR, Stiffness (MPa) 1500 maximum
D.Reclaimed Asphalt Concrete Pavement and Shingles. Do not use reclaimed asphalt concrete pavement except as described in 443.03.C. Do not use reclaimed asphalt shingles.
E.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 f rom moisture or other contamination.
1.Cellulose Fibers. Add the fiber at a dosage rate of 0.3 to 0.4 percent by weight of the total mix as directed by District Testing to control draindown in production. TABLE 443.03-4 CELLULOSE FIBER REQUIREMENTS Property Limits Fiber Length (max) 0.25 inches (6.35 mm) No. 100 (150 μm) [Alpine Sieve Method, percent passing] 60 to 80 No. 20 (850 μm) [Ro-Tap Sieve Method, percent passing] 80 to 95 No. 40 (425 μm) [Ro-Tap Sieve Method, percent passing]] 45 to 85 No 100 (150 μm) [Ro-Tap Sieve Method, percent passing] 5 to 40 Ash Content 18% non-volatiles (±5%) pH 7.5 (±1.0) Oil Absorption (times fiber weight) 5.0 (±1.0) Moisture Content (max) 5.0%
2.Cellulose Pellets. Cellulose pellets consist of cellulose fiber and may be blended with 0 to 20 percent asphalt binder. Meet the cellulose fiber requirements above. If no asphalt binder is used, add the pellet at a dosage rate of 0.3 to 0.4 percent by weight of the total mix as directed by District Testing to control draindown in production. Adjust the fiber dosage to maintain the desired fiber amount when fiber is pre-blended with binder. TABLE 443.03-5 CELLULOSE PELLET REQUIREMENTS Maximum Pellet size 1/4 cubic inch (4000 mm3) Binder 25 to 80 pen.
3.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 to 0.4 percent b y weight of the total mix as directed by District Testing to control draindown in production. TABLE 443.03-6 MINERAL FIBER REQUIREMENTS Average Fiber length (max) 0.25 in (6.35 mm) Average Fiber thickness (max) 0.0002 in (0.005 mm) Shot content (ASTM C612) Percent Passing No. 60 (250 µm) sieve Percent Passing No. 230 (63 µm) sieve 90 to 100 65 to 100 Degradation (max)[1] 30 percent [1] (GeorgiaDOT-124/McNett) - copy available from OMM .
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, print out the feed rate of the feeder supply system, and include a transparent pipe section for observing flow consistency. District Testing will approve the fiber feed system prior to the start of production by a trial load of SMA and inspection of the bag house collected material. Conduct and document a weekly qu ick 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 percent 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 °F (180 °C). 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 percent 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 °F (149 °C) for PG 70-22M and 310 °F (154 °C) for PG 76-22M. Due to sample variability with SMA, a larger than usual sample size from which m aterial 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 District Testing 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 OMM.
A.Test Strips and JMF Adjustment . Do not begin full production of the SMA until receiving authorization from District Testing. 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. During the construction of a test strip, perform one 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 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. OMM will notify District Testing of any JMF adjustments. Do not start production until notified by District Testing.
B.Hauling. Provide SMA at a minimum of 300 °F (148 °C) when it arrives at the paver, unless otherwise approved by OMM. If draindown is evident when discharging into the paver, shorten the storage time and increase the fiber dosage.
C.Compaction. Start compaction immediately after the SMA has been placed. 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 or large fat spots develop, cease production until resolved. Do not compact SMA that is below 230 °F (110 °C).
443.08 Acceptance. After accepting the test strips, the Department will base acceptance of the
asphalt concrete mix on the method specified in the Contract line item description (i.e., 446 or 447).
443.09 Basis of Payment. Include the cost of asphalt material to coat vertical faces and seal
joints and gutters in the contract unit price for Item 443.The Department will pay for accepted quantities at the contract prices as follows: Item Unit Description 443 Cubic Yard Stone matrix asphalt concrete, 12.5mm, (Cubic Meter) PG70-22M, (___) 443 Cubic Yard Stone matrix asphalt concrete, 12.5mm, (Cubic Meter) PG76-22M, (___)
Referenced in this section
Stone Matrix Asphalt Concrete in other states
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Source: Construction and Material Specifications, 2023 (rev. 7/17/2026) Edition. Pages 241–245 of 892. View official source ↗