Page 389 - Mechanics of Asphalt Microstructure and Micromechanics

Simulation of Asphalt Compaction 381

15%
15%
1F
F
2F
10% 2F
10% 3F
VVF 4F VVF 3F
4F
5%
5%
0%
0%
0 1 2 3 4 5 6 7 8 9 10 11 12
0 1 2 3 4 5 6 7 8 9 10 11 12
Passage Passage
(a) (b)
FIGURE 11.13 Change of VVF under different roller pressures at (a) bottom and (b) mid height of a
typical section.

The changes of VVF (void volume fraction, or air-void content) at the bottom and
mid-height of the AC section against the roller passage are plotted in Figure 11.13. It can
be seen that the targeted compaction air-void content (or density) can be achieved much
earlier (four to six passages) for forces 3F and/or larger in this case. Figure 11.13 also
indicates that the bottom layer is less effectively compacted.
To further explore how compaction is achieved at different locations of a layer, re-
sponses of sub-layers corresponding to different locations are presented in Figure 11.14.
It can be noted that the layer at the bottom is typically less compacted. With larger com-
paction forces, the compaction rates increase.

15%
15%
Bottom
Layer2
10%
10% Layer3
VVF Bottom VVF Mid
Layer2
5% 5%
Layer3
Mid
0% 0%
0 1 2 3 4 5 6 7 8 9 10 11 12 0 1 2 3 4 5 6 7 8 9 10 11 12
Passage Passage
(a) (b)
15% 15%
Bottom Bottom
Layer2 Layer2
10% Layer3 10% Layer3
VVF Mid VVF Mid
5% 5%

0% 0%
0 1 2 3 4 5 6 7 8 9 10 11 12 0 1 2 3 4 5 6 7 8 9 10 11 12
Passage Passage
(c) (d)
FIGURE 11.14 Change of VVF at different locations under different roller forces: (a) 1F, (b) 2F, (c) 3F, and
(d) 4F.