This method, the simplest, calculates the volume based on height and diameter/width measurements. This method has shown some promise in both accuracy and precision. This method calculates specimen volume like the parafilm method but uses a vacuum chamber (see Figure 3) to shrink-wrap the specimen in a high- quality plastic bag (see Figure 4) rather than cover it in a paraffin film. However, in practice the paraffin film application is quite difficult and test results are inconsistent. Since the specimen is completely wrapped when it is submerged, no water can get into it and a more accurate volume measurement is theoretically possible. This method wraps the specimen in a thin paraffin film (see Figure 2) and then weighs the specimen in and out of water. In practice, the paraffin is difficult to correctly apply and test results are somewhat inconsistent. Therefore, after the wax sets there is no possibility of it draining out and, theoretically, a more accurate volume can be calculated. This method determines volume similarly to the water displacement method but uses a melted paraffin wax instead of water to fill a specimen’s internal air voids (see Figure 1). One critical problem with this method is that if a specimen’s air voids are high, and thus potentially interconnected (for dense-graded HMA this occurs at about 8 to 10 percent air voids), water quickly drains out of them as the specimen is removed from its water bath, which results in an erroneously low volume measurement and thus an erroneously high bulk specific gravity. This SSD condition allows for internal air voids to be counted as part of the specimen volume and is achieved by soaking the specimen in a water bath for 4 minutes then removing it and quickly blotting it dry with a damp towel. SSD is defined as the specimen condition when the internal air voids are filled with water and the surface (including air voids connected to the surface) is dry. The most common method, calculates the specimen volume by subtracting the mass of the specimen in water from the mass of a saturated surface dry (SSD) specimen. The difference in weights can then be used to calculate the weight of water displaced, which can be converted to a volume using the specific gravity of water. These methods, based on Archimedes Principle, calculate specimen volume by weighing the specimen (1) in a water bath and (2) out of the water bath. There are several different ways to measure bulk specific gravity, all of which use slightly different ways to determine specimen volume: This reliance on bulk specific gravity is because mix design is based on volume, which is indirectly determined using mass and specific gravity. The bulk specific gravity is a critical HMA characteristic because it is used to calculate most other HMA parameters including air voids, VMA, and TMD. The three primary mixture characterization tests discussed here are:īulk specific gravity is essentially the density of a compacted (laboratory or field) HMA specimen. Reliance Specialty Products specifically developed and formulated EnTron™-AE to exacting standards for asphalt extraction applications.Mixture characterization tests are used to describe fundamental mixture parameters such as density and asphalt binder content. Differences in purity, moisture content, non-volatile residue, and stabilizers can affect the performance.
Care must be taken when choosing an nPB based solvent for your asphalt extraction application.
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