ASPHALT BINDERS AND ASPHALT MIXTURES - Materials for Civil and Construction Engineers - page 350

mix-design procedure based on this type of compaction. However, the Su-
perpave mix design method (FHWA, 1995) uses a gyratory compactor; thus,
this compaction method is now common. Figure 9.23 shows the Superpave
gyratory compactor.
In the Marshall procedure (Figure 9.24), a slide hammer weighing 4.45 kg
(10 lb) is dropped from a height of 0.46 m (18 in.) to create an impact com-
paction force (ASTM D1559). The head of the Marshall hammer has a diameter
equal to the specimen size, and the hammer is held flush with the specimen
at all times.
In the California kneading compactor method (Figure 9.25), the area of the
compactor foot is smaller than the area of the mold. After each compaction
stroke the mold is rotated, subjecting the asphalt mixture to a kneading action
(ASTM D1561). After the kneading compaction is complete, the specimen is

Height
measurement

Control and data
acquisition panel

Reaction
frame

Loading ram

Mold

FIGURE 9.23 Superpave
gyratory compactor.

Rotating base

FIGURE 9.24 Marshall compactor.