| Test Setup | Sensor Information |
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 Vehicle
Configuration |
Sensor Diagrams |
 Wander Pattern |
Sensor Table |
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Test Area Diagram |
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Material Properties |
Construction Cycle Three (CC-3) involved the replacement of the low strength CC-1 test items and the removal of a Portland Cement Concrete (PCC) test strip with a series of four flexible pavement (LFC) sections having increasing subbase depths.
Removals reached depths of 3-feet in to the subgrade. The upper layer of the new pavements, which were of conventional construction, consisted of 5-inches of P-401 asphalt concrete placed in two 2 ½-inch lifts. A tack coat was placed between the lifts. The base material consisted of 8- inches of P-209 crushed stone base placed in two lifts and compacted as one. P-154 granular material formed the subbase. The subbase was placed and compacted in lifts of about 6-inches. Four depths of subbase were used forming four pavement sections having a progressively greater number of passes to failure when subjected to traffic loading. Subbase thicknesses in LFC-1, LFC-2, LFC-3, and LFC-4 were 16-, 24-, 34-, and 43-inches respectively. The upper two feet of the subgrade, for all the sections, were reprocessed and compacted in 6-inch lifts using clean material from the excavation. Construction was completed in August 2002.
The test items covered a length of 345 feet and a width of 66 feet. The breakdown was as follows: Transition 0, Station – 20 to 0; LFC-1, LFC-2, LFC-3, LFC-4, with Transitions 1, 2, and 3, Station 0 to 300; and Transition 4, Station 300 to 325. (station is the distance from the origin)
About 200 sensors were embedded in the pavement structure. The sensors were of two types, static and dynamic. Static sensors were used to monitor temperature in the asphalt and moisture in the subgrade on an hourly basis. Dynamic sensors measured strains in the asphalt, pressure and compression in the subgrade, and deflections throughout the depth of the pavement structure (Multi-Depth Deflectometers, MDD’s). Two pressure sensors were also placed at the interface between the base and subbase layers. Test vehicle operations triggered data retrieval from the dynamic sensors. Static and dynamic sensor data were processed and stored in a computer database maintained on-site. The database facilitated review of the data for analysis at a later time. Traffic testing was performed with six (6) wheel loading on the north side and four (4) wheel loading on the south side. Rut depth and profile measurements were made on the top surface of the asphalt as the traffic testing progressed.
Tests were planned with six-wheel and four-wheel landing gear loads.
The traffic data for flexible and rigid pavement test items is available. Daily and monthly traffic repetitions, as well as current traffic totals, are given for each test item. It is strongly recommended that users consult this table to become familiar with the trafficking history before searching the static and dynamic data.
After the flexible test items were declared “failed”, trenches were cut in the transverse direction in the pavement. The purpose of the trenches was to conduct posttraffic investigation into the failure mechanism of the pavement structure. The trenching involved removal of the P-401 AC layer, the P-209 crushed stone base, and the P-154 subbase layer to reveal the subgrade interface and subsequent subgrade layers below. The final trench dimensions were 60 feet (18.3 m) long (across the width of the test pavement), 4 feet (1.22 m) wide, and the depth varied depending on the test section. Tests and measurements were performed on the various layers of the pavement structure. After the completion of testing, the trench walls were cleaned to clearly expose the layer interfaces. Measurements of the pavement layer interface profiles were made relative to a horizontal string line to quantify the contribution of each component layer to the total pavement rutting and upheaval.
