423.01 Description.
yard within a tolerance of - 0.02 and +0.02 gallons per square yard. A uniform distribution of tack coat across the mat shall be enforced and streaked tack shots shall not be accepted.
c.Conventional Paving Equipm ent with the use of “PG Asphalt for Trackless Tack ” The use of conventional paving equipment shall be allowed when the tack coat material used is “PG Asphalt for Trackless Tack” meeting the requirements given in Subarticle 420.02. "PG Asphalt for Trackless Tack" shall be applied at a temperature of 300 °F to 375 °F, on a clean dry surface.
d.Spray Paver Paving Equipment with the use of CQS -1HP Asphalt Emulsion The requirements given in Article 410.03 shall be applicable to the construction of the open gra ded friction course except for the following: • The paving machine shall incorporate a tack distribution system, receiving hopper, feed conveyor, and a variable width, heated, ironing or vibratory type screed. • The tack distribution system shall include meter ed mechanical pressure sprayer to accurately apply and monitor the rate of application of the emulsion for the tack. The rate shall be uniform across the entire paving width. It shall be applied at a temperature of 140 – 180 °F. Application shall be immedi ately in front of the screed unit. No wheel or other part of the paving machine shall come in contact with the tack before the paving mix is applied. • Extensions added to the screed shall be provided with the same heating capability as the main screed unit , except for use on variable width tapered areas as approved by the Engineer.
e.Compaction Equipment . Item 410.03(a)5 is amended to require that steel wheel tandem (7 ton {6 metric ton} minimum size) rollers shall be furnished in sufficient numbers based on the quantity of material being placed to provide effective compaction coverage within the workable time period of the mix as designated by the Engineer. Rubber -tire rollers shall not be used.
f.Weather and Temperature Limitations . The weather, air, and surface temperature limitations for (polymerized) HMA mixes are found in Subarticle 410.03(b).
g.Compacting . Subarticle 410.03(g) is amended to require that rolling shall be as approved by the Engineer; no density tests will be required.
420.05 Method of Measurement.
The accepted quantities of polymer modified open graded friction course will be measured as provided in Article 410.08. The CQS -1hp emulsion or “PG Asphalt for Trackless Tack” for the tack coat will be measured in gallons in accordance with the requirements given in Article 109.02.
420.06 Basis of Payment.
a.Unit Price Coverage . Polymer Modified Open Graded Friction Course, measured as noted above, will be paid for at the contract unit price bid in accordance with Article 410.09. The unit price of the Open Graded Friction Course Tack Coat shall be full compensation for all materials, equipment, and labor required to furnish and place the tack.
b.Payment will be made under Item No .: 420 - A Polymer Modified Open Graded Friction Course – per ton {metric ton} 420 - B Open Graded Friction Course Tack Coat – per gallon STONE MATRIX ASPHALT (SMA) (FIBER STABILIZED ASPHALT CONCRETE)
423.01 Description.
The work covered by this Section shall consist of constructing a hot mix asphalt layer of fiber stabilized stone matrix asphalt pavement on a prepared surface in accordance with these specifications
423.02 Materials.
and in conformity with the lines, grades, typical cross section, and the plac ement rate shown on the plans or as directed. The plant, equipment, and construction requirements for this pavement are specified in Sections 106 and 410, subject to any exceptions herein. All 423 mixes shall be designed and produced in accordance with the requirements given in this Section and ALDOT -395, SMA Mix Design.
423.02 Materials.
a.Aggregates .
1.Procedure for Acceptance of Coarse and Fine Aggregates . All fine and coarse aggregate furnished shall come from an approved producer who is participatin g in and meeting the requirements of ALDOT- 249, Procedure for Acceptance of Coarse and Fine Aggregates. The producer's name shall be listed in the Department's Materials, Sources, and Devices with Special Acceptance Requirements Manual, List I-1. The Depar tment has established a list of qualified producers of fine and coarse aggregates. Refer to Subarticle 106.01(f) and ALDOT -355 concerning this list.
2.Types of Acceptable Coarse Aggregates for SMA. Coarse aggregate shall be aggregate retained on the No. 4 {4.75 mm} sieve. The virgin coarse aggregate shall be 100% crushed granite, quarried quartzite, limestone, sandstone, slag, or other 100% crushed manufactured stone meeting the requirements given in Section 801.
3.Flat and Elongated Particles in Coarse A ggregates for SMA. The maximum amount of flat and elongated particles in coarse aggregate for SMA is given in the following table. PERCENT OF FLAT AND ELONGATED PARTICLES IN COARSE AGGREGATE FOR SMA Test Method Maximum Flat & Elongated % by Count 3:1 (max to min) ASTM D 4791 Section 8.4 20 % Flat & Elongated % by Count 5:1 (max to min) ASTM D 4791 Section 8.4 5 %
4.Coarse Aggregate Soundness for SMA. The percent degradation of the source aggregate by the sodium sulfate soundness test (AASHTO T 104, Soundness of Aggregate by Use of Sodium Sulfate or Magnesium Sulfate ) after five cycles of testing shall not exceed 10 %.
5.Deleterious Materials and Absorption in Coarse Aggregate for SMA. The amount of deleterious substances and absorption in the coarse aggregate shall not exceed the limits given in the following table. DELETERIOUS MATERIALS AND ABSORPTION IN COARSE AGGREGATE FOR SMA Coal and Lignite (Visual) 0.25 % Clay Lumps and Friable Particles (AASHTO T 112) 0.25 % Other local deleterious substances (Shale, Mica, Marcasite, etc.) (Visual) 2.0 % Absorption (Absorption on the material passing the 3/4 inch {19.0 mm} sieve and retained on the No. 4 {4.75 mm} sieve) (AASHTO T 85 *). Applies to gravel aggregates only. 2.0 % * Section 8.1 of AASHTO T 85 modified to require a 15 minute vacuum saturation period as per Section 6.3 of AASHTO T 209 prior to the required 15 -19 hour soaking period.
6.Los Angeles Abrasion Criteria for Coarse Aggregate for SMA. The percent loss of the coarse aggregate by the LA Abrasion test (AASHTO T 96, Resistance to Abrasion of Small Size Aggregate by use of the Los Angeles Machine ) shall not exceed 48 % except that, for Sandstone and Blast Furnace Slag, the LA Abrasion shall not exceed 55 %.
7.Fine Aggregate for SMA . Fine aggregate shall be 100% crushed granite, limestone, sandstone, slag, or other 100% crushed manufactured stone meeting the requirements of S ection 802 and the following table. The parent material shall meet the requirements given in Section 801.
423.02 Materials.
FINE AGGREGATE QUALITY REQUIREMENTS FOR SMA Test Method Minimum Maximum Uncompacted Voids %, AASHTO T 304* 45 % 100 % Sand Equivalent %, AASHTO T 176* 50 % 100 % Liquid Limit %, AASHTO T 89 0 % 25 % Plasticity Index, AASHTO T 90 Non-plastic *The Sand Equivalent and Uncompacted Voids may be run on the blend of the aggregates. The fine aggregate shall be non -plastic when tested in accordance with AASHTO T 89, as modified by ALDOT -232, and AASHTO T 90 and shall have a maximum of 1.0 % clay lumps and friable particles as determined by AASHTO T 112. It shall consist of hard, tough grain, free of injurious amounts of clay, loam, or other deleterious substances.
8.Mineral Filler for SMA. The mineral filler shall meet the requirements of Section 8 05.
b.Recycled Asphalt Pavement (RAP) & Reclaimed Asphalt Shingles (RAS). The requirements for allowing the use of RAP and RAS are given in Article 410.02.
c.Blend of Aggregates . The combined aggregates shall conform to the percent passing by volume requirements given in the following table. PERCENT PASSING BY VOLUME OF AGGREGATE FOR SMA Sieve Size 1.5 inch {37.5 mm} Maximum Aggregate Size 1 inch {25.0 mm} Maximum Aggregate Size 3/4 inch {19.0 mm} Maximum Aggregate Size 1/2 inch {12.5 mm} Maximum Aggregate Size 3/8 inch {9.5 mm} Maximum Aggregate Size Lower Limit Upper Limit Lower Limit Upper Limit Lower Limit Upper Limit Lower Limit Upper Limit Lower Limit Upper Limit 1.5 inch {37.5 mm} 100 100 1 inch {25.0 mm} 90 100 100 100 3/4 inch {19.0 mm} 30 86 90 100 100 100 1/2 inch {12.5 mm} 26 63 50 74 90 100 100 100 3/8 inch {9.5 mm} 24 52 25 60 26 78 90 100 100 100 # 4 {4.75 mm} 20 28 20 28 20 28 26 60 90 100 # 8 {2.36 mm} 16 24 16 24 16 24 20 28 28 65 # 16 {1.18 mm} 13 21 13 21 13 21 13 21 22 36 # 30 {600 µm} 12 18 12 18 12 18 12 18 18 28 # 50 {300 µm} 12 15 12 15 12 15 12 15 15 22 # 200 {75 µm} 8 10 8 10 8 10 8 10 12 15 An example of how to blend aggregate based upon volume can be found in ALDOT -395, SMA Mix Design. The production tolerances for the above gradation bands are as specified in Item 410.02( d)7, except that the tolerance for the No. 4 {4.75 mm} sieve is +/ - 4% and for the 3/8 inch {9.5 mm} sieve is +/- 6%. Aggregates that tend to polish under traffic, such as limestone, dolomite, or marble, shall be permitted only in widening as defined by Article 410.01, shoulder paving, underlying layers, and layers that are to be covered by Polymer Modified Open Graded Friction Course (Secti on 420) mix in this contract, except as noted in the following table.
423.03 Design.
ALLOWABLE CARBONATE STONE CRITERIA FOR SMA BPN 9 Value Of Aggregate Source * Maximum Allowable Percentage Of Carbonate Stone ≤ 25 30 26 through 28 35 29 through 31 40 32 through 34 45 ≥ 35 50 * This value, BPN 9, is made using the British Pendulum Tester on aggregate source specimen polished for 9 hours on an accelerated polishing machine known as the British Wheel as per A STM D 3319, ASTM E 303 and BMTP -382. In no case shall the total amount of virgin carbonate stone in the combined mixture used as actual wearing surface layers exceed the percentage shown in the table above . When parts of the carbonate stone used in the mi x are from differing strata of material or coming from multiple sources that are represented by different BPN 9 values, the lowest BPN 9 value will be used.
d.Liquid Asphalt Binder .
1.Required Type of Liquid Asphalt Binder for SMA. Unless otherwise shown on the plans, for pavement layers in the top 2 inches the liquid asphalt binder shall meet the requirements of Section 804 and shall be polymer -modified to meet a PG 76 -22 as given in S ection 811. For pavement layers below the top 2 inches the liquid asphalt binder shall be PG 67 -22 and shall meet the requirements of Section 804. If Open Graded Friction Course (Section 420) layers are required, the top 2 inches shall be measured from the bottom of the Open Graded Friction Course layer.
2.Required Minimum Amount of Liquid Asphalt Binder for SMA. The minimum liquid asphalt binder content shall be as given in the following table (by weight {mass} of total mix. MINIMUM LIQUID ASPHALT BINDER CONTENT FOR SMA Maximum Aggregate Size (inches) {mm} Nominal Aggregate Size (inches) {mm} Minimum Liquid Asphalt Binder Content (% by weight) {% by mass} Minimum Liquid Asphalt Binder Content for mixes containing RAS (% by weight) {% by mass} 1.5 {37.5} 1.0 {25} 5.3 5.5 1.0 {25.0} 3/4 {19.0} 5.5 5.7 3/4 {19.0} 1/2 {12.5} 5.7 5.9 1/2 {12.5} 3/8 {9.5} 5.9 6.1 3/8 {9.5} No. 4 {4.75} 6.1 6.3
3.Liquid Asphalt Binder Draindown. A fiber stabilizer meeting the requirements given in Section 410 shall be incorporated into the mix to reduce draindown. The fiber shall be blended into the mix in accordance with the requirements given in Section 410. RAS may be allowed as a fiber stabili zer provided it meets the requirements in Section 410.
423.03 Design.
All SMA mixes shall be designed according to ALDOT -395, SMA Mix Design. SMA mixes shall be designed using a 50 blow Marshall design or a 60 gyration gyratory compactor design. The SMA shall have a minimum VMA of 17, a VCA MIX less than the VCA DRC (calculating Voids in the Coarse Aggregate is explained in ALDOT- 395 SMA Mix Design) and air voids of 3.5% for SMA mixes containing RAS or 4.0 % for all other SMA mixes. The SMA mix shall be des igned with a minimum tensile strength ratio of 0.80 according to ALDOT -361. All SMA mixes shall be tested for susceptibility to rutting in accordance with the latest approved version of AASHTO T 324 Hamburg Wheel -Track Testing of Compacted Asphalt Mixtures . All Mixes shall be tested at 50°C. SMA mixes using PG 67 -22 binder shall exhibit 10 mm rutting or less at 10,000 cycles. SMA mixes using PG 76 -22 binder shall exhibit 10 mm rutting or less at 20,000 cycles.
423.07 Basis of Payment.
423.04 Hot Mix Asphalt Plant Requirements.
a.Mineral Filler . To ensure accurate metering and proportioning, the introduction of the mineral filler shall be in accordance with Section 4.3 of AASHTO M 156 as specified in ALDOT -324. Adequate dry storage shall be provided for the mineral filler. In a batch plant, mineral filler shall be added directly into the weigh hopper. In a drum plant, mineral filler shall be added directly into the drum mixer near enough to the liquid asphalt binder line so that the mineral filler is captured by the liquid asphalt binder. Note: For most SMA projects, the flow rate of the mineral filler governs the plant production rate.
b.Hot-Mixture Storage . SMA shall be stored according to the requirements as given in ALDOT 324, “Plant Requirements for Plants Producing Hot -Mixed, Hot -Laid Asphalt Mixtures”. SMA shall not be heated above 350 °F {177 °C} without the approval of the Engineer.
423.05 Construction Requirements.
a.General . Construction requirements shall be the same as specified in Articles 410. 03 through 410.07 except as noted in this Article.
b.Weather and Temperature Limitations . The weather, air and surface temperature limitations for (polymerized) HMA mixes are found in Subarticle 410.03(b).
c.Surface Preparation . A thin tack coat meeti ng the requirements of Section 405 shall be applied to ensure uniform and complete adherence of the overlay.
d.Compaction . Due to the nature of stone matrix asphalt mixture, the surface shall be rolled immediately. Rollers shall move at a uniform speed, not to exceed 3 miles per hour {5 km/hr}, with the drive roller nearest the paver. Rolling shall be continued until all roller marks are eliminated and the required density has been obtained. The Contractor shall monitor density during the compaction proc ess using the nondestructive testing devices approved in Section 306 of the Specifications to ensure that the required density is being obtained. The device shall either be calibrated to roadway cores or gage counts and shall be used to determine the roll ing pattern producing maximum density. If vibratory compaction causes aggregate breakdown or forces liquid asphalt binder to the surface, the vibratory mode shall be turned off and the roller shall operate in static mode only. To prevent adhesion of the m ixture to the rollers, it shall be necessary to keep the rollers properly moistened with water mixed with very small quantities of detergent or other approved material.
423.06 Method of Measurement.
The accepted quantities of stone matrix asphalt binder la yer and stone matrix asphalt wearing layer will be measured as provided in Article 410.08. The SMA mix shall be evaluated for liquid asphalt binder content, laboratory compacted air voids, and in -place density; pay factors will be applied.
423.07 Basis of Payment.
a.Unit Price Coverage . Stone Matrix Asphalt Binder Layer and Stone Matrix Asphalt Wearing Layer, measured as noted above, will be paid for at the contract unit price bid in accordance with Article 410.09.
b.Payment will be made under Item No .: 423-A Stone Matrix Asphalt Wearing Layer, * Maximum Aggregate Size - per ton {metric ton} 423-B Stone Matrix Asphalt Binder Layer, * Maximum Aggregate Size - per ton {metric ton} * Specify Maximum Aggregate Size, either 1.5, 1, 3/4, 1/2 or 3/8 inches { 37.5 mm, 25 mm, 19 mm, 12.5 mm, or 9.5 mm}
424.01 Description
SECTION 424 SUPERPAVE BITUMINOUS CONCRETE BASE, BINDER, AND WEARING SURFACE LAYERS
424.01 Description
The work covered by this Section shall consist of a hot or warm bituminous plant mixed pavement layer placed on a prepared surface in accordance with these specifications and in reasonably close conformity with the lines, grades, typical cross section, and placement rate shown on the plans or as directed by the Engine er. The Contractor may use either hot mix or warm mix for all Superpave ESAL Range mixes in Section 424. General requirements for all bituminous concrete pavements as specified in Section 410 are applicable to this Section, subject to any exceptions conta ined herein. Quality Control/Quality Assurance (QC/QA) requirements as specified in Section 106 are applicable to this section, subject to any exceptions contained herein. The work will be accepted on a LOT by LOT basis in accordance with the applicable re quirements.
424.02 Materials.
The materials furnished for use shall conform to the requirements of Section 410 and the following:
a.Aggregates .
1.Procedure for acceptance of Coarse and Fine Aggregates. All fine and coarse aggregate furnished shall come from an approved producer who is participating in and meeting the requirements of ALDOT- 249, Procedure for Acceptance of Coarse and Fine Aggregates. The producer's name shall be listed in the Department's Materials, Sources, and Devices with Special Accept ance Requirements Manual, List I-1. The Department has established a list of qualified producers of fine and coarse aggregates. Refer to Subarticle 106.01(f) and ALDOT -355 concerning this list.
2.Types of acceptable Coarse Aggregates for Superpave. Coarse aggregate shall be aggregate retained on the No. 4 {4.75 mm} sieve. Coarse aggregate shall consist of crushed (or uncrushed) gravel with a bulk specific gravity greater than 2.550 (AASHTO T 85), crushed stone, or crushed slag, or a combination thereof hav ing hard, strong, durable pieces, free from adherent coatings, and meeting all requirements of these specifications.
3.Flat and elongated particles in Coarse Aggregates for Superpave. The maximum amount of flat and elongated particles in coarse aggregate for Superpave is given in the following table. PERCENT OF FLAT AND ELONGATED PARTICLES IN COARSE AGGREGATE FOR SUPERPAVE Test Method Maximum Flat & Elongated % by Count 5:1 (max to min) ASTM D 4791 Section 8.4 10 % * * Shall not apply to the 3/8 inch {9.5 mm} mix or to ESAL Range A/B
4.Coarse Aggregate Soundness for Superpave. The percent degradation of the source aggregate by the sodium sulfate soundness test (AASHTO T 104, Soundness of Aggregate by Use of Sodium Sulfate or Magnesium Sulfate) after five cycles of testing shall not exceed 10 %.
5.Deleterious Materials and Absorption in Coarse Aggregate for Superpave. The amount of deleterious substances and absorption in the coarse aggregate shall not exceed the following limits:
Source: Alabama Standard Specifications for Highway Construction, 2022 Edition. Pages 232–236 of 934.