Technical information

3-29
the G-8 gauge. At this point we do not have a good explanation for these obscure
behaviors.
-200
-150
-100
-50
0
50
100
150
200
0 40 80 120 160 200 240
APT Carriage Location [in.]
Bottom of HMA Strain (in X) [microstrains]
Pass #5,000
Pass #80,000
Loading Direction
G-1,
Centerline
G-3,
Centerline
G-6,
2ft Off-Center
G-8,
2ft Off-Center
Figure 3.5.4: Measured horizontal strains at the bottom of the HMA in the transverse
direction to the loading during pass #5,000 (solid line) and pass #80,000 (dashed line).
3.5.3 Rutting and Cracking Performance
Periodically, the APT carriage was halted for mapping of surface cracks and so that
rutting measurements could take place. No cracking information is available from the
APT study as cracks did not appear on the surface throughout the experiment.
Reportedly, a very few hairline cracks did appear at the very end of the experiment in
Section n1 (see Table 3.4.3). Their location and orientation, however, was not mapped
before digging out the materials to make room for the following APT study.
The device for obtaining transverse profiles consists of a vertical rod with a
small wheel attached to its tip. The rod is moved manually along a guided straight line
across the pavement, with its rolling wheel in continuous contact with the surface.
During this process both vertical and horizontal movements are collected providing
about 680 data pairs. Horizontal position is measured with a cable-based transducer
while the vertical position is measured using an LVDT. The entire device is attached to