AASHTO PP77:14(2020) StandardI Practice for Materials Selection and Mixture Design of Permeable| Friction Courses (PFCs).
7.3.3. Determine the mixing and compaction temperatures in accordance with T 245, Section 3.3.1. The mixing temperature shall be the temperature needed to produce an asphalt binder viscosity of 170 ± 20 cSt. The compaction temperature shall he the temperature required to provide an asphalt binder viscosity of 280 ± 30 cSt. The selected temperatures may need to be changed for modified asphalt binders: in such a case, follow the binder supplier’s guidelines for mixing and compaction temperatures.
7.3.4. For each test specimen, weigh into a pan the appropriate amount of each size fraction to produce the required sample size. Mix the aggregates in each pan and place in an oven set to a temperature no more than 28°C (50°F) above the mixing temperature determined in Section 7.3.3.
7.3.5. Heat the asphalt binder to the mixing temperature determined in Section 7.3.3.
7.3.6. When preparing PFC in the laboratory, use a mechanical mixing apparatus. Place the heated aggregate batch into the mechanical mixing container. Add the required amounts of asphalt binder and any stabilizing additive into the container. Mix the aggregate, asphalt binder, and stabilizing additives rapidly until thoroughly coated. Mixing times for PFC should be slightly longer than for conventional mixtures to ensure that the stabilizing additives are thoroughly dispersed within the mixture. After mixing, short-term age the PFC mixture in accordance with R 30.
Note 2—Dry-mixing fibers, if used, into the aggregate before adding the asphalt binder has been found to help disperse the fibers uniformly throughout the mixture.
7.3.7. Sainpk compaction—Compact three individual specimens of each trial blend at the established compaction temperature using 50 revolutions of the Superpave gyratory compactor in accordance with T 312.
Note 3—More than 50 revolutions should not be used; PFC is relatively easy to compact in the laboratory and exceeding this compactive effort can cause excessive aggregate breakdown.
7.3.8. After the samples have been compacted and are stable enough to prevent damage. extrude them from the molds and allow them to cool. Determine the bulk specific gravity of each specimen using T 331 or by dimensional analysis. To use dimensional analysis, determine and record the dry mass of each specimen in grams. Determine and record the height of each specimen in centimeters in accordance with ASTM E3549/D3549M using calibrated calipers. Determine the diameter of each specimen in centimeters as the average of four equally spaced measurements using the calibrated calipers. Calculate the area of the specimen using the average diameter,. Calculate the volume of the specimen by multiplying the specimen area by its average height. Calculate the bulk density of the specimen by dividing the dry mass of the specimen by the calculated volume. Convert the bulk density into the bulk specific gravity, Gmh, by dividing by 0.99707 g/cm3, the density of water at 25°C (77°F).AASHTO PP77 pdf download.