A Manual for Design of Hot-Mix Asphalt with Commentary (2011) / Chapter Skim
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Pages 194-206
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From page 194... ...
Additionally, new technologies were adopted from Europe for stone matrix asphalt (SMA) , gap-graded hot mix asphalt (GGHMA)
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From page 195... ...
Finally, the design gradation at optimum asphalt binder content is evaluated for moisture susceptibility. This manual does not include provisions for performance testing of PFC mixtures, because there is limited experience at present in performing and interpreting rut resistance tests on this type of material.
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From page 196... ...
Flow diagram illustrating PFC mix design methodology.
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From page 197... ...
Because of the open-graded aggregate structure, the aggregate surface area of PFCs is very low. Like GGHMA and SMA, PFC mixes are required to have a relatively high asphalt binder content.
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From page 198... ...
When using polymer or rubber as a stabilizer, the amount of additive added should be that amount necessary to meet the specified performance grade of the asphalt binder. Cellulose fibers are typically added to a PFC mixture at a dosage rate of 0.3% by total mixture mass.
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From page 199... ...
Sieve Size, mm 9.5-mm PFC 12.5-mm PFC 19-mm PFC Grading Requirements % Passing 25mm 100 19mm 100 85-100 12.5mm 100 80-100 55-70 9.5mm 85-100 35-60 -- - 4.75mm 20-30 10-25 10-25 2.36mm 5-15 5-10 5-10 75µm 0-4 0-4 0-4 Table 11-3. Cellulose fiber requirements.
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From page 200... ...
200 A Manual for Design of Hot Mix Asphalt with Commentary 19.0 mm OGFC Gradation Requirements 0 10 20 30 40 50 60 70 80 90 100 Sieve Size, mm (raised to 0.45 power) Pe rc en t P as si ng 0.60.075 1.18 2.36 4.75 9.5 12.5 19 25 12.5 mm OGFC Gradation Requirements 0 10 20 30 40 50 60 70 80 90 100 Sieve Size, mm (raised to 0.45 power)
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From page 201... ...
Selection of Trial Asphalt Binder Content The minimum desired asphalt binder content for PFC mixtures is presented in Table 11-6. Table 11-6 illustrates that the minimum asphalt binder content for PFCs is based on the combined bulk specific gravity of the aggregates used in the mix.
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From page 202... ...
202 A Manual for Design of Hot Mix Asphalt with Commentary Combined Aggregate Bulk Specific Gravity Minimum Asphalt Content Based on Mass, % 2.40 6.8 2.45 6.7 2.50 6.6 2.55 6.5 2.60 6.3 2.65 6.2 2.70 6.1 2.75 6.0 2.80 5.9 2.85 5.8 2.90 5.7 2.95 5.6 3.00 5.5 Table 11-6. Minimum asphalt content requirements for aggregates with varying bulk specific gravities -- PFCs.
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From page 203... ...
where Pca = percent of coarse aggregate in the mixture Gmb= combined bulk specific gravity of the total aggregate Gca = bulk specific gravity of the coarse aggregate Once VTM and VCAMIX are determined, each trial blend mixture is compared to the PFC mixture requirements, which are presented in Table 11-7. The trial blend with the highest air void content that meets the 18% minimum and exhibits stone-on-stone contact is considered the design gradation.
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From page 204... ...
1 2 2 100 11 5( ) 204 A Manual for Design of Hot Mix Asphalt with Commentary Property Requirement Asphalt Binder, % Table 10-6 Air Void Content, % 1 18 to 22 Cantabro Loss % 15 max.
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From page 205... ...
Decreasing the percent passing the breakpoint sieve will generally increase the air void content at a given asphalt binder content. Voids in the Coarse Aggregate If the VCAmix is higher than that in the dry-rodded condition (VCADRC)
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From page 206... ...
Bibliography AASHTO Standards AASHTO M 320, Performance-Graded Asphalt Binder AASHTO R 30, Mixture Conditioning of Hot-Mix Asphalt AASHTO T 19, Bulk Density ("Unit Weight") and Voids in Aggregate AASHTO T 96, Resistance to Degradation of Small-Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine AASHTO T 104, Soundness of Aggregate by Use of Sodium Sulfate or Magnesium Sulfate AASHTO T 176, Plastic Fines in Graded Aggregates and Soils by Use of the Sand Equivalency Test AASHTO T 209, Theoretical Maximum Specific Gravity and Density of Bituminous Paving Mixtures AASHTO T 245, Resistance to Plastic Flow of Bituminous Mixtures Using Marshall Apparatus AASHTO T 283, Resistance of Compacted Asphalt Mixtures to Moisture-Induced Damage AASHTO T 304, Uncompacted Void Content of Fine Aggregate AASHTO T 305, Determination of Draindown Characteristics in Uncompacted Asphalt Mixtures AASHTO T 326, Uncompacted Void Content of Coarse Aggregate (As Influenced by Particle Shape, Surface Texture and Grading)
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