Technical information

3-18
Loading of Section n1 began on July 19, 2004. About 90,000 passes were
applied by August 11, 2004, all without wander. The last 2,500 cycles where applied
overnight, during which a bond failure occurred between the surface and intermediate
HMA lifts. At the onset of failure, the surface lift in the wheel path area was sheared-off
in the direction of loading, exposing the intermediate HMA lift. Subsequently the
loading of lane 1 was stopped, and the APT loading frame was switched to lane 2.
Section n2 incurred about 2,500 passes beginning September 13, 2004, before it became
apparent that another bond failure was rapidly developing, again at the interface
between the surface and intermediate HMA lifts. Subsequently, it was decided not to
wait for complete shear failure, but to mill and repave the surface HMA lift in both
sections. This sequence of events is summarized in Table 3.4.1.
Table 3.4.1: APT pass application log for sections n1 and n2 (original structure).
Date Section Cumulative Passes Days
19-Jul-04
n1
0 0
22-Jul-04 5,000 3
23-Jul-04 10,000 4
25-Jul-04 20,000 6
27-Jul-04 30,000 8
29-Jul-04 40,000 10
30-Jul-04 50,000 11
2-Aug-04 60,000 14
6-Aug-04 70,000 18
9-Aug-04 80,000 21
11-Aug-04 90,000 23
Loading stopped due to bond failure between top and intermediate
HMA layers.
13-Sep-04 n2 2,500 1
Signs of bond failure between top and intermediate HMA layers;
surface asphalt layer on both sections was milled and repaved.
Resurfacing of the surface HMA lift took place between September 13 and
September 28, 2004 (no construction details are available). Reloading of section n2
began on the latter date and continued until February 1, 2005, at which point 187,500
passes had been applied. The first 40,000 passes were applied without wander; wheel