SECTION 412 – SUPERPAVE MIXTURE DESIGN, CONSTRUCTION OF PLANT-MIXED HMA/WMA 6.3MM THIN ASPHALT OVERLAY COURSES
412.1 DESCRIPTION – This work is the construction of a thin lift wearing course of plant-mixed, dense-graded HMA/WMA asphalt concrete with 6.3 mm Nominal Maximum Aggregate Size (NMAS), placed on a prepared surface.
412.2. MATERIALS –Section 409.2 with additions and modifications as follows:
(a) Bituminous Material
1. Virgin Mix. Furnish PG 76-22, conforming to the requirements of Standard Specifications for Performance-Graded Asphalt Binder, AASHTO M 320 or PG64E-22, conforming to the requirements of Standard Specifications for Performance-Graded Asphalt Binder Using Multiple Stress Creep Recovery (MSCR) Test, AASHTO M332, except as revised in Bulletin 25. Obtain material from a source listed in Bulletin 15 for the specified grade. Provide Quality Control (QC) testing and certification as specified in Sections 106.03(b) and 702.1(b)1. Provide the Representative a copy of a signed Bill of Lading for bituminous material on the first day of paving and when the batch number changes.
When producing a mixture with a WMA technology, adhere to the following requirements:
a. WMA Technology Additives or Modifiers Blended at the Bituminous Material Supplier’s Refinery or Terminal. Provide refinery or terminal blended bituminous material blended with a WMA Technology additive or modifier from an approved manufacturer and source listed in Bulletin 15. Include in the bituminous material Producer QC Plan, the WMA Technology additive or modifier manufacturer name, WMA Technology name, and source, dosage rates, blending method, QC testing, corrective action points, disposition of failed material, storage, handling shipping, and bill of lading information following the applicable requirements in Section 702. Include the WMA Technology additive or modifier and dosage rate on the bill of lading. Provide certification that the refinery or terminally blended bituminous material modified with the WMA Technology additive or modifier meets the requirements for the specified grade.
b. WMA Technology Additives or Modifiers Blended at the Bituminous Mixture Producer’s Plant. Provide a blended bituminous material consisting of an approved WMA Technology additive or modifier from an approved manufacturer and source listed in Bulletin 15 that is blended with a base bituminous material of the specified grade conforming to the requirements of Standard Specifications for Performance-Graded Asphalt Binder, AASHTO M 320, except as revised in Bulletin 25 and from an approved source listed in Bulletin 15, Section 702. Prepare a Producer QC Plan as specified in Section 106 and conforming to the Producer QC Plan requirements in Section 409.2(e)1.a and the additional Producer QC Plan requirements within this specification. Provide certification that the bituminous material blended with the WMA Technology additive or modifier at the bituminous mixture production plant meets the requirements for the specified grade.
(b) Aggregate
1. General Requirements. Provide aggregate from approved producers and sources listed in Bulletin 14. Furnish aggregate that conform to the quality requirements for Superpave Asphalt Mixture Design as specified in Bulletin 27 with modifications as specified in 412.2. Provide aggregate with at least the SRL designation specified. To achieve the specified SRL, the Contractor may provide a blend of two aggregates if the blend has an SRL designation equal to or better than that specified. Blends are 50% by mass (weight) of each aggregate. Blend the aggregates using an approved method.
2. Fine Aggregate. Section 703.1, except Table A gradation does not apply and as follows:
· Determine the uncompacted void content according to AASHTO T 304, Method A, or use the value listed in Bulletin 14, and conform to AASHTO M 323, Table 5.
· Determine the sand equivalent value according to AASHTO T 176 and conform to AASHTO M 323, Table 5.
All manufactured sand fine aggregates used in NMAS 6.3 mm mixtures must be from a source that has a coarse aggregate SRL rating listed in Bulletin 14 as specified. Manufactured sand fine aggregate must be manufactured from the same parent material(s) as the Buletin 14 listed coarse aggregate, and will have the same SRL rating as the listed coarse aggregate.
All natural sand fine aggregates, and manufactured sand fine aggregates without a coarse aggregate from the same source with an SRL rating listed in the Bulletin 14 used in NMAS 6.3 mixture must be submitted to the LTS for SRL determination.
3. Coarse Aggregate. Type A, Section 703.2, except Table C gradation does not apply and revise the following requirements of Table B:
· Abrasion, Maximum Percent as specified in Bulletin 27, Chapter 2A, Table 5A
· Flat and Elongated Particals in Coarse Aggregate maximum percent as specified in ASTM D4791using material retained on the No. 4 sieve, Maximum 10 percent for 1:5 ratio, and Maximum 20 percent for 1:3 ratio.
· Crushed Fragments, Minimum Percent, as specified in AASHTO M 323, Table 5, for Fractured Faces, Course Aggregate using the material retained on the No. 4 sieve.
The coarse aggregate must satisfy specified SRL requirements. Do not use coarse aggregate or anti-skid aggregate in the mixture until the quality, type, and SRL, are determined.
(c) Recycled Asphalt Material. Do not use Reclaimed Asphalt Pavement (RAP) or Recycled Asphalt Shingles (RAS) in the 6.3 mm HMA Wearing Course.
(d) Filler. Follow Section 703.1(c)1. Do not use fly ash if the design traffic is greater than or equal to 3 million Equivalent Single Axle Loads (ESALs). Hydrated lime is allowed as a filler, and may constitute up to two percent of the weight of total dry aggregate unless otherwise shown on the plans. Provide hydrated lime that conforms to the requirements of ASTM C977.
(e) Mixture Composition.
1. Virgin Material Mixtures. Design 6.3 mm NMAS mix that meets all Department requirements. Size, uniformly grade, and combine aggregate fractions, bituminous material, and an approved WMA Technology when WMA is indicated in proportions to develop a Job Mix Formula (JMF) that conforms to the material, gradation, and volumetric Superpave Asphalt Mixture Design requirements as specified in Bulletin 27, Chapter 2A, except as modified in Table A.
For WMA mixtures, the WMA Technology Manufacturer Technical Representative (Technical Representative) will address laboratory procedure modifications necessary to prepare, compact, and test WMA mixtures and to achieve a uniform blend. When WMA is indicated develop a HMA JMF and incorporate the WMA Technology additive, modifier, or process into that JMF during production. Do not develop a volumetric WMA JMF based on incorporating the WMA Technology additive, modifier or process during the volumetric asphalt mixture design process. For all WMA JMFs, perform moisture susceptibility analysis according to Bulletin 27.Ensure the WMA Technology additive, modifier, or process is not detrimental to the moisture resistance of the mixture. For tracking purposes, create a separate WMA JMF cover sheet (TR-448A) for approval containing the WMA Technology used, WMA Technology dosage rate, material code, and the AASHTO T 283 (TSR) data from the WMA moisture susceptibility testing.
Submit a complete copy of the JMF, including a Form TR-448A signed by a certified HMA Level 2 Plant Technician, to the DME/DMM at least 3 weeks before the planned start of mixture production. Include a list of all material sources and the HMA producer on the TR-448A. Provide the calibration factors (Cf for both asphalt content and #200 sieve)) required by PTM No. 757 with the JMF on the TR-448A. Do not start mixture production until after the DME/DMM reviews the JMF.
Submit a completely new JMF, including a new Form TR-448A, with a change in material sources or if a new JMF is necessary to produce a mixture conforming to this specification.
TABLE A
Mix Design Requirements for Thin Lift 6.3 mm HMA Wearing Course
AGGREGATE GRADATION REQUIREMENTS, PERCENT PASSINGSieve Size / Min. – Max.
3/8” / 100 Min.
1/4” / 90-100
No. 4 / 0-85
No. 8 / 37-55
No. 50 / 8-25
No. 200 / 3-10
VOLUMETRIC DESIGN REQUIREMENTS
Design Gyrations (Ndesign) for All Specified Ranges of Design ESALs / 75
Voids in Mineral Aggregate (VMA), Min. %, for All Specified Ranges of Design ESALs / 16.5
Design Air Voids (Va), %, for All Specified Ranges of Design ESALs / 3.5-4.0
Binder Draindown (AASHTO 305) for mixture with greater than 7.0% Asphalt Content / 0.3%
Binder Grade for All Specified Ranges of Design ESALs > 3 Million
AASHTO M 320 or AASHTO M 332 / PG 76-22,
PG 64E-22,
1.a Producer QC Plan. Section 409.2(e)1.a
1.b Plant Technicians. Section 409.2(e)1.b
1.c Annual JMF Verification. Section 409.2(e)1.c except conform to the single and multiple sample tolerances in Section 412.2(e)1.d Tables B and C. Perform annual verification of the WMA mixture JMF even if the equivalent HMA mixture JMF was previously annually verified.
1.d Production. Section 409.2(e)1.d except as follows:
When producing WMA, produce and test mixtures, including Superpave Gyratory Compactor (SGC) specimens for quality control using the same test methods, procedures and frequencies as specified for HMA, except as modified by the Producer QC Plan. Maintain records of the testing of WMA and make available for review by the Representative when requested.
1.d.1 Apparent Moisture Content. Section 409.2(e)1.d.1
1.d.2 Asphalt Content. Include in the producer QC Plan a frequency of obtaining mixture samples according to PTM No. 1 and performing asphalt content tests to verify that the mixture conforms to the tolerances of Table B. Test the samples according to either PTM No. 757, PTM No. 702, or PTM No. 742. After obtaining a minimum of three test results, determine compliance with the multiple sample tolerances in Table B. After obtaining five or more test results, determine compliance with the multiple sample tolerances in Table B using the running average of the last five consecutive test results.
Printed ticket results may be used in place of laboratory test results for QC of asphalt content of the mixture if the producer is currently approved to use printed tickets according to Bulletin 27. During mixture production, maintain 90% of printed ticket results for each day of production within 0.2 percentage points of the JMF.
1.d.3 Gradation. Sample the completed mixture, or sample the combined aggregate from the hot bins of a batch plant or the combined aggregate belt of a drum plant, according to PTM No. 1 and at the frequency in the producer QC Plan. If mineral filler is used in the mixture, determine gradation by testing samples of the completed mixture.
· Test the completed mixture according to PTM No. 757 or according to PTM No. 702 and PTM No. 739.
· Test combined aggregate samples according to PTM No. 743.
Produce a mixture within the tolerances of Table B. Determine compliance with the multiple-sample tolerance after obtaining a minimum of three test results for the mixture. After obtaining five or more test results for the mixture, determine compliance with the multiple-sample tolerances using the running average of the last five consecutive test results.
1.d.4 Theoretical Maximum Specific Gravity. Section 409.2(e)1.d.4
1.d.5 Volumetric Analysis of Compacted Specimens. Sample the completed mixture according to PTM No. 1 and at the frequency in the producer QC Plan. Prepare a minimum of two specimens from each sample according to AASHTO T 312. In case warm mix asphalt is used, follow Section 411 for specific temperature requirements and the acceptable temperature range.
Produce a mixture with volumetric properties conforming to the tolerances of Table C. Determine the bulk specific gravity of the specimens as specified in AASHTO T 312 and calculate air voids (Va) and Voids in Mineral Aggregate (VMA) at Ndesign according to AASHTO R35 and as specified in Bulletin 27.
TABLE B
Composition Tolerance Requirements of the Completed Plant Mix
Single Sample(n = 1) / Multiple Samples
(n 3)
Gradation
Passing 1/4” to No. 50 Sieves (Inclusive) / ±6% / ±4%
Passing No. 200 Sieve / ±3.0% / ±2.0%
Asphalt Content
6.3mm HMA / ±0.6% / ±0.4%
Temperature of Mixture (F)
Class of Material / Type of Material / Minimum / Maximum
PG 76-22 or PG 64E-22 (HMA/WMA) / Asphalt Cement / 285 / 330
Job-Mix Tolerance Requirements for Combined Hot Bin Gradations
Gradation / Single Sample (n = 1)
Passing 1/4” to No. 50 Sieves (Inclusive) / ±4%
Passing No. 200 Sieve / ±3.0%
TABLE C
Volumetric Tolerance Requirements of the Plant Mixed, Laboratory Compacted Mixture
Single Specimen(n = 1) / Multiple Specimens
(n 2)
Air Voids at Ndesign (Va) from Target 4.0% / +2.0% / +1.5%
Minimum VMA % / 16.0 / -
1.e Corrective Actions. Immediately take corrective actions if one or more of the following occurs:
· QC test results on a single sample (n=1) for percent passing the 1/4” sieve, No. 8 sieve, No. 50 sieve, No. 200 sieve, or asphalt content are not within the tolerances in Table B.
· The average of multiple samples (n3) for percent passing any sieve or asphalt content, as determined according to Section 409.2(e)1.d, are not within the tolerances in Table B.
· QC test results on a single specimen (n=1) or on multiple specimens (n2) are not within the tolerances in Table C.
· Independent assurance (IA) or QA sample results tested at the producer's plant are not within the tolerances of Tables B or C.
After taking corrective actions, sample the completed mixture within 150 tons of production. After sampling, test the mixture and provide test results to the Representative. If less than three samples are tested for mixture composition, determine conformance with Table B by comparing each result to the multiple sample tolerances. If the mixture does not conform to the single and multiple sample tolerances in Table B and the single and multiple specimen tolerances in Table B, suspend production and shipping to the project and determine the cause of the problem. Provide a written explanation of the problem and a proposed solution to the Department. After the Representative reviews the proposed solution and authorizes production to continue, resume production and perform JMF verification according to the QC Plan. During corrective actions and JMF verification, mixture acceptance is according to the approved acceptance level of Section 409.2(f) Table C.
2. Draindown Sensitivity. For mixtures with greater than 7 percent total asphalt content determine the driandown sensitivity of the mixture using AASHTO T 305 at the maximum mixture temperature listed in Table B minus 5°F. Use Fibers to reduce binder draindown if draindown exceeds the requirements of Table A. Use stabilizer types specified in Section 419.2(d) as needed to address draindown.