Phase II: CC4 SCI Validation Test (October - April 2008)

Full-scale test of PCC overlays on damaged rigid pavements.

 

1. Test Objective 6. Material Characterization Plan & Data
2. Test Plan 7. Painting Plan

2a. Gear Configuration

8. Pavement Distress map (Concrete)

2b. Wheel Load/Tire Pressure

9. Post Traffic Testing

2c. Wander Pattern

            9a. CBR 
3. Pavement Construction/Cross Section             9b. HWD
4. Instrumentation Plan             9c. PLATE LOADS
5. NDT Plan & Data 10. Search The Database
  

The Construction Cycle Five (CC-4) Validation Test Items were built to provide information on the effects of further deterioration of the underlying concrete layer on the performance of the concrete overlay. Construction consisted of removal of the concrete overlay and thin asphalt interlayer of the Baseline Test Items and replacing them in kind to form the Validation Test Items. The concrete underlying layer was retained so as to undergo additional deterioration at varying degrees under traffic loading.


The Test Setup description remains the same as given for the Baseline Test Items (CC-4). Instrumentation was similar and again included both dynamic and static sensors.


Test vehicle operations triggered data retrieval from the dynamic sensors at an increased sampling rate. Sensor data collected during both traffic and non-traffic time periods were processed and stored in a computer database maintained on-site. The database facilitated review of the data for analysis at a later time.

CC4 Pavement Construction/Cross-Section

An approximately 300-foot test pavement was constructed as the Baseline Experiment at FAA’s testing facility. It was constructed on the medium subgrade, and had three structural crosssections as shown in figures 1 and 2.


The underlying slabs were not designed to be distressed (no shattered or cracked slabs), but to have different joint matching conditions to determine how underlying discontinuities (including cracks) affect the overlay’s performance. Having an intact underlay also allowed investigation of relative rates and patterns of deterioration of the underlying pavement due to overlay loading.


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Thus, the final design for each experiment consisted of six test items of 12 slabs each. The test items were separated by transition slabs in both the longitudinal and transverse directions. By providing two test items in each structural section, different loading configurations could be applied.

CC4 Pavement Construction/Cross-Section (con.)

Figure 1 shows the three structural cross-sections, numbered 1, 2, and 3 from west to east. The relative thicknesses were designed to encompass most unbonded overlay thickness to existing underlying pavement thickness configurations found in practice, while still having absolute thicknesses that could be accommodated within the testing bed.


Figure 2 shows the transverse cross-sections, indicating that each structural cross-section has two 12.5-ft wide lanes, with a 10-ft transition slab between the test items. The slabs in the north lane were loaded with a triple dual tandem gear, while the slabs in the south lane were loaded with a twin dual tandem gear. The resulting six test items are summarized in table 2.



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Joint patterns were established to create matched and mismatched transverse joints in the underlying slab and the concrete overlay as shown in figure 1. All longitudinal joints were mismatched or offset as shown in figure 2. The underlay joints were sawcut and not doweled. The overlay joints were all doweled and sawcut, both in a transverse and longitudinal manner. As discussed in a later section, the structural cross-section was loaded alternately from west to 6 east and east to west. The loading direction may affect responses of both the pavement and instrumentation, so the relative position of joint offset is illustrated.