Construction and Maintenance Practices for Permeable Friction Courses (2009) / Chapter Skim
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From page 91... ...
Guidelines on the Use of Permeable Friction Courses
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From page 92... ...
C O N T E N T S G-1 Introduction G-2 Objective G-2 Report Organization G-3 Standard Practice for Materials, Design and Construction of Permeable Friction Courses G-20 Standard Method of Test for Determining the Abrasion Loss of Permeable Friction Course (PFC) Asphalt Specimens by the Cantabro Procedure G-26 Standard Practice for Maintenance and Rehabilitation of Permeable Friction Courses (PFC)
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From page 93... ...
Gradations associated with the OGFCs of the 1970s and 1980s were much coarser than typically used dense-graded mixes (Marshall and Hveem designed mixes) .Additionally, very few states were using modified asphalt binders.
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Without water on the pavement surface, the frictional properties of the pavement improve, splash and spray is reduced, and the potential for hydroplaning is greatly reduced. OGFCs that are designed to have at least 18 percent air voids are called permeable friction courses (PFCs)
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G-3 Standard Practice for Materials, Design and Construction of Permeable Friction Courses AASHTO Format
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________________________________________________________________________ 2. REFERENCED DOCUMENTS 2.1 AASHTO Standard: M 156, Requirements for Mixing Plants for Hot-Mixed, Hot-Laid Bituminous Paving Mixtures M 231, Weighing Devices Used in the Testing of Materials M 320, Performance-Graded Asphalt Binder R 30, Mixture Conditioning of Hot-Mix Asphalt (HMA)
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From page 97... ...
3.1.7 stabilizing additive -- materials used to minimize draindown of asphalt during transport and placement of PFC. 3.1.8 voids in coarse aggregate – the volume of voids between the coarse aggregate particles, where this volume includes filler, fine aggregate, air voids, asphalt binder, and stabilizing additives, if used.
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From page 98... ...
Materials needing selection include coarse aggregates, fine aggregates, asphalt binder and stabilizing additives. 6.1.1 Coarse Aggregates -- Table 1 presents the coarse aggregate requirements for permeable friction courses.
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Adjustments should be an increase of one high-temperature grade for all other roadways. 6.1.4 Stabilizing Additives -- Stabilizing additives are needed within permeable friction courses to prevent the draining of asphalt binder from the coarse aggregate skeleton during transportation and placement.
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6.2.3 Selection of Trial Asphalt Content -- The minimum desired asphalt binder content for permeable friction course mixtures is presented in Table 4. These minimum asphalt binder contents are provided to ensure sufficient volume of asphalt binder exists in the PFC mix.
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From page 101... ...
Compaction temperature will be the temperature required to provide an asphalt binder viscosity of 280+ 30 cSt. However, while these temperatures work for neat asphalt binders, the selected temperatures may need to be changed for modified asphalt binders.
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From page 102... ...
6.2.5 Number of Samples per Trial Blend -- A total of eighteen samples are initially required: three samples for determining air voids and three uncompacted samples for determining theoretical maximum density at each binder content. Each sample is mixed with the trial asphalt binder content and three of the four samples for each trial gradation are compacted.
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From page 103... ...
6.3.1 Cantabro Abrasion Loss -- The Cantabro Abrasion test is used as a durability indicator during the design of OGFC mixtures. In this test, three OGFC specimens compacted with 50 gyrations of the Superpave gyratory compactor are used to evaluate the durability of an OGFC mixture at a given asphalt binder content.
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From page 104... ...
6.5.6 Volumetric properties, abrasion loss on unaged specimens, and draindown for each trial blend and at the optimum asphalt binder content. 6.5.7 Moisture susceptibility recommendations, and 6.5.8 Recommended job-mix formula for the permeable friction course.
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From page 105... ...
This may be done by modifying the asphalt binder at the refinery or by adding an asphalt binder modifier to the PFC mixture during production. Some projects have utilized both a fiber and a modified asphalt binder.
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From page 106... ...
The asphalt binder in PFC can be modified at the refinery, or, in some cases, the modifier is added at the hot mix plant. For the first method, the hot mix producer takes delivery of the modified asphalt binder and meters it into the mixture in a traditional manner.
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From page 107... ...
7.2.2 Plant Production Temperature - Production temperatures of PFC mixtures vary somewhat according to aggregate moisture contents, weather conditions, grade of asphalt binder and type of stabilizing additive used. However, experience indicates that normal HMA production temperatures or slightly higher are adequate.
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From page 108... ...
Most agencies limit haul distance to 50 miles or haul times to 1 hour. Due to high asphalt binder contents, PFC may adhere to truck beds somewhat more than conventional HMA mixtures.
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From page 109... ...
A tolerance of + ¼ inch in the lift thickness is allowable. 7.5.5 Placement and Finishing - Immediately behind the paver, PFC mixtures are known to be harsh and very sticky.
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Some modified asphalt binders may require special testing techniques. 7.7.3 Trial Sections - Prior to full-scale production and placement, a trial section of the mixture should be produced and placed by the contractor.
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From page 111... ...
has also been shown to work well for determining the asphalt binder content of PFC. After removing the asphalt binder the aggregate should be graded according to AASHTO T27.
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G-20 Standard Method of Test for Determining the Abrasion Loss of Permeable Friction Course (PFC) Asphalt Specimens by the Cantabro Procedure AASHTO Format
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SCOPE 1.1 This standard covers a test method for determining the percent abrasion loss of permeable friction course (PFC) asphalt specimens using the Los Angeles abrasion machine.
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_______________________________________________________________________ 5. SIGNIFICANCE AND USE 5.1 The procedure described in this test standard is used to indirectly assess the cohesion, bonding, and effects of traffic abrasion and, when used with other tests, to determine the optimum asphalt binder content during PFC mixture design that will provide good performance in terms of permeability and durability when subjected to high volumes of traffic.
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8.3 Preparation of Laboratory-Molded Specimens 8.3.1 Prepare replicate mixtures (Note1) at the appropriate aggregate gradation and asphalt binder content.
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/ W 1] x 100 where: PL = Cantabro abrasion percent loss, W 1 = initial weight of the specimen, and W 2 = final weight of the specimen 10.2 Calculate the mean particle loss of all specimens tested.
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________________________________________________________________________ 13. KEYWORDS 13.1 permeable friction courses, gyratory, Cantabro Abrasion G-25
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G-26 Standard Practice for Maintenance and Rehabilitation of Permeable Friction Courses (PFC) AASHTO Format
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From page 119... ...
TERMINOLOGY 3.1 Definitions 3.1.1 Permeable Friction Courses (PFC) – special type of porous hot-mix asphalt mixture with air voids of at least 18 percent used for reducing hydroplaning and potential for skidding, where the function of the mixture is to provide a free-draining layer that permits surface water to migrate laterally through the mixture to the edge of the pavement.
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Fog seals do not affect the macrotexture of PFC layers; therefore, the reduced potential for hydroplaning is maintained. 6.1.3 Corrective surface maintenance activities are those conducted to repair minor surface distresses in PFC layers.
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________________________________________________________________________ 7. REHABILITATION OF PERMEABLE FRICTION COURSE 7.1 Rehabilitation of PFC layers can be categorized as minor or major rehabilitation activities.
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7.1.2 PFC layers should not be overlaid with dense-grade hot-mix asphalt. 7.1.3 There is some evidence in Europe that hot in-place recycling can be utilized to rehabilitate a PFC layer.
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