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Test Area Diagram |
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Wander Pattern
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The purpose of the Construction Cycle Five (CC-5) Test Strip was to provide a flexible pavement with which the adequacy of DuPont Clay for use as stable low strength subgrade material could be determined. DuPont Clay had previously been used as a medium strength subgrade material in Construction Cycles One, Two and Four (CC-1, CC-2 and CC-4). It showed stability of moisture and strength with time. County Sand and Stone Clay (a silty clay) had been used as a low strength subgrade in Construction Cycles One and Three (CC-1 and CC-3). It showed a loss of moisture and a gain in strength with time.
The CC-5 Test Strip effort involved the replacement of LFC-1 and LFC-2 of the CC-3 Test Items with similarly designated test areas. Removals penetrated the County Sand and Stone Clay low strength subgrade of the CC-3 Test Item Construction.
An additional 36 inches of County Sand and Stone Clay was placed above the surface at the excavated depth on the south side. It was placed in five lifts with four lifts at a thickness of 8 inches and a single lift of 12 inch thickness at the bottom. It was conditioned to an average CBR of 3.0 at an average moisture content of 25.4%. DuPont Clay was placed above the County Sand and Stone Clay to a depth of 36 inches on the north side. It was placed in six lifts of 6 to 8 inch thickness and conditioned to an average CBR of 3.5 at an average moisture content of 36.0.
P-154 granular subbase material consisting of crushed quarry screenings was placed above. It was placed in four lifts of 5 to 8 inch thickness with the greater thickness lifts below. Subgrade surface levels had been adjusted (stepped) so that LFC-1 of the Test Strip received 16 inches of the P-154 subbase and LFC-2 received 24 inches. The LFC-1 subbase was placed in three lifts and LFC-2 subbase was placed in four lifts. A compaction level of 97% was achieved at an average moisture content of 4.2% in the subbase of LFC-1 and a compaction level of 96% was achieved at an average moisture content of 4.6% in the subbase of LFC-2.
An 8 inch depth of Dense Graded Aggregate (DGA) base was placed on the P-154 subbase. The base was placed and compacted in two 4 inch lifts. A compaction level of 102% was achieved at an average moisture content of 2.3%. The Test Strip pavement was completed with the placement and compaction of a 2.5 inch thick New Jersey Department of Transportation (NJDOT) Hot Mix Asphalt (HMA) surface. Five paving lanes were used. Construction was completed on February 13, 2007.
LFC-1 and LFC-2 were further designated as North and South (N and S) to cover the variable of subgrade type.
The Test Strip covered a total length of 170 ft. and a width of 64 ft.
| Test Strip Area/Transition | Stations |
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| Transition 0 | -20 to 0 |
| LFC-1 N LFC-1 S | 0 to 30 |
| Transition 1 | 30 to 50 |
| LFC-2 N LFC-2 S | 50 to 100 |
| Transition 2 | 100 to 150 |
One experimental Multidepth Deflectometer (MDD) was placed in the Dupont Clay subgrade and that area of the Test Strip tested with a single wheel. The effort served as the precursor to the development of the 4 Horizontal Position Devices (HPD’s) ultimately placed in the subgrade of the CC-5 Test Items.
Three longitudinal recessed strips were provided in the surface of the DGA base within Transition 2. One strip was 8.5 ft. wide, 1 inch deep, extending from station 110 to 150 at the north edge; the second was 9.5 ft. wide, 2 inches deep, extending from station 110 to 150 at the south edge; and the third 12 ft. wide, 2 inches deep, extending from station 100 to 150 at the pavement centerline. The top surface of the HMA was placed level with no recesses. The purpose of the recessed strips in the DGA base was to study the response of the asphalt paving machines to the resulting bumps as determined by the FAA profiler and the accompanying FAA pavement roughness software.
The traffic data for the flexible pavement test strip are available. Daily and monthly traffic repetitions, as well as the traffic totals, are given for each test area. It is strongly recommended that users consult this table to become familiar with the trafficking history.
