904 PERFORMANCE GRADED ASPHALT BINDERS AND ASPHALT MIXES
From MDOT Policy Manual
- The manufacturer and hauler shall furnish certifications as specified in TC-1.03 and the following:
- The manufacturer shall certify:
- (a) Date and time of loading.
- (b) Tank or blending system.
- (c) Identification of hauling unit.
- (d) Binder grade, temperature, and quantity of materials.
- (e) Complete certified analysis.
- (f) Lot number, if applicable.
- The hauler shall certify:
- (a) Identification of hauling unit.
- (b) Binder grade and source of last delivery.
- (c) The date of the last delivery using this hauling tank and volume of material remaining in the tank at the time of current loading.
904.02 PERFORMANCE GRADED ASPHALT BINDERS.
- M332 Table 1, for mixes containing all virgin materials, recycled asphalt pavement materials, or roofing shingles from manufacturing waste. The Office of Materials Technology’s (OMT) Asphalt Technology Division (ATD) will approve all PG binders. Submit certification from an approved supplier per M332 showing the final product meets specifications.
- Chemical or organic additive suppliers shall supply the dosage rate and provide certification of the resultant PG binder.
- The PG binder for asphalt mixes shall be achieved by the use of Neat Asphalt with elastomer polymer modifications when needed. Modifications to PG binder shall be as approved.
- 902.02.01 Warm Mix Asphalt (WMA) PG Binders. Include the PG binder performance grade test data over the range of WMA additive percentages proposed for WMA use. An AASHTOAmerican Association of State Highway and Transportation Officials accredited laboratory shall be employed to perform all required WMA binder laboratory testing.
904.03 EMULSIFIED ASPHALTS.
- M140 or M208, and M316 with the following exceptions:
- (a) Cement mixing tests are waived.
- (b) Maximum of 3.0 percent by volume of oil distillate.
- (c) The sieve test requirement for field samples shall be a maximum of 0.4 percent.
904.04 ASPHALT MIXES.
- Section 915. Asphalt mixes shall be produced as specified.
- 904.04.01 Aggregates. M323 and Section 901. Test the aggregate retained on the 4.75 mm sieve for flat and elongated particles per D4791. Recycled asphalt pavement used in an asphalt mix shall be considered an aggregate source per 900.03.
- 904.04.02 Mix Design. Develop asphalt mix designs in conformance with R35, M323 and MSMT 416, except replace “Table 6, Superpave HMA Design Requirements” in M323 with the following:
DESIGN LEVEL 20-Year Design Traffic, ESALs Ndesign 1 <300,000 50 2 300,000 to <3,000,000 65 3 3,000,000 to <10,000,000 80 4 10,000,000 to <30,000,000 80 5 ≥30,000,000 100
- Design asphalt mixes for the Equivalent Single Axle Loading (ESAL) range specified.
- Asphalt mixes designed with Reclaimed Asphalt Pavement (RAP) and/or Reclaimed Asphalt Shingles (RAS) shall also conform to MSMT 412.
- 904.04.03 Mix Design Approval. Submit data from the laboratory study to OMT for tentative approval at least 30 days prior to paving operations. Submit mix designs in an approved format. Include the following:
- (a) Mix designation.
- (b) Source, percentage, and grade of performance graded asphalt binder.
- (c) Source, gradation, and proportion of each component aggregate.
- (d) Target aggregate gradation.
- (e) Plant where the asphalt mix will be produced.
- (f) Plant target mixing temperature based on viscosity of 0.22 Pa·s.
- (g) Ratio of dust to binder material on effective asphalt.
- (h) Maximum specific gravity at the target binder content.
- (i) Mix design grading plotted on 0.45 power gradation chart.
- (j) Tensile strength ratio and worksheets.
- (k) The bulk specific gravity and gyratory weight at Ndesign gyrations.
- (l) The air void content (percent Va) at Ndesign gyrations.
- (m) The voids in the mineral aggregate (percent VMA) and the voids filled with asphalt (percent VFA) at Ndesign gyrations (T 312).
- (n) All consensus and source properties.
- (1) Coarse aggregate angularity.
- (2) Flat and elongated.
- (3) Sand equivalent.
- (4) Uncompacted void content of fine aggregate.
- (5) Bulk and apparent specific gravity of coarse and fine aggregate.
- (6) Absorption of coarse and fine aggregate.
- Include the quantity of job mix formula aggregate and appropriate amount of required PG binder for ignition oven calibration with each mix design submitted for approval.
- When previous construction or performance experience has shown the proposed mix design to be unsatisfactory, OMT may require submission of a more suitable design.
- (a) When a change to the source of aggregate used in the mix is proposed, submit a revised mix design as specified.
- (b) Notify OMT two working days in advance if a change in the PG binder source becomes necessary.
- (c) Conduct a stripping test per MSMT 410 and submit an initial PG binder sample for testing and approval. OMT may require an anti-stripping additive test per D4867 before approval.
- 904.04.04 WMA Mix Design Approval. 904.04.03 and the following:
- (a) Warm Mix technology and/or additive information.
- (b) WMA manufacturer’s established target rate for water and additives and the acceptable variation for production.
- (c) Producer’s compaction temperature of gyratory specimens.
- (d) The producer shall follow the manufacturer’s recommendation for incorporating additives and WMA technologies into the mix per the manufacturer’s recommendations.
- When a foaming, chemical or organic additive is used, submit the appropriate job mix formula (JMF) per R35 for approval.
- (a) All WMA technology methods shall require a mix design/field placement demonstration on a non-AdministrationShall mean any one of the Administrations within the Maryland Department of Transportation, as listed in GP 1.02. project once the JMF is approved and before verification, or as approved. Notify OMT two working days prior to shipment.
- (b) A technical representative from the product supplier must be present during the initial shipment and placement of the WMA when a chemical or organic additive is used.
- (c) If all specification requirements are met, this is a one-time demonstration per product, per plant, or with a combination of products.
- (d) The demonstration may be waived if the asphalt producer has successfully placed WMA on other projects with the same aggregates and can provide testing data and contact information.
- 904.04.05 Verification of Mix Design. Conduct a verification of the mix at the beginning of production in each plant after receiving tentative approval for the design.
- (a) Notify the EngineerAny person designated by the Administrator or the procurement officer, acting directly or through his duly authorized representative, such representative acting within the scope of the particular duties assigned to him or of the authority given him. and OMT at least two working days in advance of the scheduled verification. Verification shall be performed by certified personnel per 504.03.
- (b) Prepare the verification samples per R35. All verification samples will be split with the OMT laboratory.
- (c) Compare and evaluate the verification test results per MSMT 735.
- 904.04.06 Verification Evaluation. MSMT 735.
- (a) Initial verification consists of four split samples tested as specified. Begin random sampling with the first day's production, with at least one split sample witnessed by an OMT representative.
- (b) If the first day of production is less than 2 000 tons, verification testing may be spread over no more than five working days with production of 200 tons or more. Complete verification testing no later than the fifth working day with production in excess of 200 tons or on the day when production has reached 2 000 tons, whichever occurs first.
- (c) Production may proceed without any changes when the ContractorAny person having a Contract with a procurement agency. Contractor does not include an employee with an employment Contract, or an employee organization with a collective bargaining agreement.’s and AdministrationShall mean any one of the Administrations within the Maryland Department of Transportation, as listed in GP 1.02.’s test results conform to a Percent within SpecificationA written description of functional characteristics, or the nature of a construction item to be procured. It may include a Limit (PWSL) of at least 85. If the mixes submitted have identical aggregate combinations and differing asphalt contents associated with changes in ESAL loads, verification may be limited to volumetric analysis, as determined.
- (d) If all test results do not conform to the parameters with a PWSL of at least 85, then an adjustment to the asphalt content or gradation may be made to bring the mix design requirements within acceptable levels. Permissible adjustment limitations between the approved Mix Design and Adjusted Mix Design are as follows:
TEST PROPERTY PERMISSIBLE ADJUSTMENT % (*) Larger than 1/2 in. (12.5 mm) sieve ± 5 1/2 in. (12.5 mm) thru No. 4 (4.75 mm) sieves ± 4 No. 8 (2.36 mm) thru No. 100 (1.50 μm) sieves ± 3 No. 200 (75 μm) sieve ± 1.0 Binder Content ± 0.20
*The permissible adjustment for all mixes shall be within control points
- (e) Perform a second verification to ensure that the modified mix conforms to all design requirements when an adjustment outside the permissible adjustment percentage is made to the mix design. Conform to the time and tonnage limitations as specified. Production may proceed when the adjusted mix is within control points and meets the PWSL. Suspend mix production and submit a new mix design for approval if the mix does not meet specifications. Design the new mix as specified.
- (f) Suspend mix production if subsequent designs submitted due to nonconformance do not meet specifications during the initial verification until corrective action is taken, as approved.
- If an adjustment to a verified mix is necessary due to aggregate changes, the mix design must meet all specification requirements before a new mix design number is issued. Verification will be based on the last 4 QA and QC production samples.
- 904.04.07 Thin Lifts. As specified in 504.03.12. Lift thicknesses shall be designated as thin lifts when the lift thickness specified does not meet 3-times nominal maximum aggregate size for fine graded mix designs or 4-times nominal maximum aggregate size for coarse graded mix designs.
- Determine fine and coarse graded thin lift mix designs per M 323 and in accordance with the table below.
Thin Lift Mix Design Identification Table Gradation Classification Control Sieve Mix Design Target (% Passing) Mix Designation Fine Graded Coarse Graded 4.75mm A thin lift is a specified pavement thickness < 1 inch. A thin lift is a specified pavement thickness < 1 inch. 9.5mm When the 2.36mm (#8) is ≥ 47%, a thin lift is a specified pavement thickness < 1 1/8 inches When the 2.36mm (#8) is < 47%, a thin lift is a specified pavement thickness < 1 1/2 inches 12.5mm When the 2.36mm (#8) is ≥ 39%, a thin lift is a specified pavement thickness < 1 1/2 inches When the 2.36mm (#8) is < 39%, a thin lift is a specified pavement thickness < 2 inches 19.0mm When the 4.75mm (#4) is ≥ 47%, a thin lift is a specified pavement thickness < 2 1/4 inches When the 4.75mm (#4) is < 47%, a thin lift is a specified pavement thickness < 3 inches 25.0mm When the 4.75mm (#4) ≥ 40%, a thin lift is a specified pavement thickness < 3 inches When the 4.75mm (#4) < 40%, a thin lift is a specified pavement thickness < 4 inches 37.5mm When the 9.50mm (3/8) ≥ 47%, a thin lift is a specified pavement thickness < 4 1/2 inches When the 9.50mm (3/8) < 47%, a thin lift is a specified pavement thickness < 6 inches
- 904.04.08 Anti-stripping Additives. D4867. Asphalt mixes shall have a Tensile Strength Ratio (TSR) of at least 0.85.
- (a) The freeze-thaw conditioning cycle is required. OMT testing of TSR’s will be performed randomly.
- (b) Asphalt mixes not meeting the minimum TSR require the use of an approved anti-stripping additive.
- (c) The producer shall determine the exact quantity of anti-stripping additive required per D4867 based on a minimum TSR of 0.85.
- (d) The dosage rate when a heat stable anti-stripping additive is used shall be at least 0.20 percent of the total weight of asphalt. The additive shall be introduced by the PG binder supplier or at the plant by line blending, metering, or otherwise measuring to ensure accurate proportioning and thorough mixing.
- (e) Hydrated lime (when used) shall conform to C 1097. Add hydrated lime in slurry form at the rate of 1.0 to 1.5 percent by weight of total aggregate. The lime slurry shall be sprayed uniformly on the aggregate on the feed belt prior to entry into the asphalt plant dryer.
- (f) Plant control and acceptance of the mix will be based on MSMT 410 per its stripping potential.
- 904.04.09 Plant Control. The following tolerances shall apply:
TABLE 904 A – DENSE-GRADED MIX TOLERANCES PHYSICAL PROPERTIES PLANT PROJECT SITE Site or Hauling
Passing No. 4 (4.75 mm) sieve and larger, % ± 7 ± 7 Passing No. 8 (2.36 mm) thru No. 100 (150 μm) sieve, % ± 4 ± 5 Passing No. 200 (75 μm) sieve, % ± 2 ± 2 Asphalt content, % ± 0.4 ± 0.5 Ratio of dust to binder material 0.6 to 1.6 (a) 0.6 to 1.6 (a) Mix temperature leaving plant vs.mix design temperature, F ± 25 NA Deviation of maximum specific gravity per lot versus design maximum specific gravity ± 0.030 ± 0.040 Voids, total mix, (VTM), % 4.0 ± 1.2 4.0 ± 1.2 Voids, total mix, 4.75 mm mix (VTM), % 3 ± 2 3 ± 2 Voids in mineral aggregate, (VMA), % ± 1.2 from design target ± 1.2 from design target Voids filled asphalt (VFA), % Within spec Within spec Bulk specific gravity, Gmb, % ± 0.022 ± 0.022
- (a) Not applicable to 4.75 mm.
- 904.04.10 PWSL Computations. As specified in 504.04.02. Perform PWSL computations for maximum specific gravity, voids in the total mix, voids in the mineral aggregate, and voids filled with asphalt. Use the moving average of the last three consecutive test values for each parameter.
- (a) If the PWSL for the three test values falls below 85, take corrective action to bring the PWSL to at least 85.
- If the PWSL drops below 68, production shall be suspended until corrective action is taken as approved.
904.05 GAP-GRADED STONE MATRIX ASPHALT (GGSMA).
- 904.05.01 Aggregates. Refer to 904.04.01.
- 904.05.02 Mix Design. Refer to 904.04.02 and the following:
MIX TOLERANCES PHYSICAL PROPERTIES MIX DESIGN VMA, % 18.0 min. VTM, % 3.5 Ndesign Gyrations 100 AC% by volume 6.5 min. Draindown, % max 0.3 Fiber stabilizer, by weight of total mix, % (a) 0.2 – 0.4
- (a) If used in mix design.
- 904.05.03 Mix Shipment and Placement Tolerances for GGSMA.
PHYSICAL PROPERTY TOLERANCE: PLANT SITE OR
HAULING UNIT SAMPLES
TOLERANCE: PROJECT SITE
BEHIND THE PAVER SAMPLES
Passing No. 3/8 (9.50 mm) sieve and larger, % ± 5 ± 5 Passing No.4 (4.75 mm) sieve, % ± 4 ± 5 Passing No.8 (2.36 mm) sieve, % ± 4 ± 5 Passing No.16 (1.18 mm) sieve, % ± 4 ± 5 Passing No.30 (0.60 mm) sieve, % ± 3 ± 4 Passing No.50 (0.30 mm) sieve, % ± 3 ± 4 Passing No.100 (0.15 mm) sieve, % ± 3 ± 4 Passing No. 200 (75 μm) sieve, % ± 2 ± 2 Asphalt content, % ± 0.4 ± 0.5 Ratio of dust to binder material NA NA Mix temperature leaving plant versus
mix design temperature, F
± 25 NA Deviation of maximum specific gravity per
lot versus design maximum specific gravity
±0.030 ± 0.040 Voids, total mix, (VTM), % 3.5 ± 1.2 3.5 ± 1.2 Voids in mineral aggregate, (VMA), % 17.0 min 17.0 min Voids filled asphalt (VFA), % NA NA Fiber Stabilizer, by weight of total mix, % ±0.1 NA
- 904.05.04 Mix Design Approval. Refer to 904.04.03.
- 904.05.05 Stabilizer. Stabilizer systems with cellulose or mineral fibers or a stabilizer system without fibers shall be as approved. Add stabilizers to the mix per the manufacturer’s recommendations.
- 904.05.06 Stabilizer Supply System for Cellulose or Mineral Fibers. A separate system for feeding shall be used to proportion the required amount into the mixture to ensure uniform distribution.
- (a) For batch plants, add the stabilizer to the aggregate in the weigh hopper and increase both dry and wet mixing times. Ensure the stabilizer is uniformly distributed prior to the addition of asphalt cement into the mixture. The plant shall be interlocked so that asphalt cannot be added until the stabilizer has been introduced into the mix.
- (b) For drum plants, add the stabilizer to the mixture in a manner that prevents the stabilizer from becoming entangled in the exhaust system.
- (c) The stabilizer supply system shall include low level and no-flow indicators, a printout of the status of feed rate in lb/minute, and a 60 second plant shut down function for no-flow occurrences.
- (d) The stabilizer supply line shall include a section of transparent pipe for observing consistency of flow or feed.
- 904.05.07 Antistripping Additives. Refer to 904.04.08.