|FHWA > Engineering > Pavements > Concrete > High Performance Concrete Pavements: Project Summary > Chapter 22|
High Performance Concrete Pavements
|DESIGN FEATURE||SECTION 32||SECTION 52||SECTION 53|
|Slab thickness, in.||5||7.5||7.5|
|Base type||7 in., aggregate||5 in., aggregate||5 in., aggregate|
|Transverse joint spacing, ft||10||15||15|
|Load transfer||None (aggregate interlock)||1-in. epoxy-coated dowels|
1.25-in. epoxy-coated dowels
1.25-in. fiber-reinforced polymer
1.50-in. fiber-reinforced polymer
|None (aggregate interlock)|
|Longitudinal joint tie bars||No. 4 bars @ 30-in. spacings||No. 4 bars @ 30-in. spacings||No. 4 bars @ 30-in. spacings|
|Lane width, ft||12 (both)||13 (outside)|
|Section length, ft||470||285||115|
|JPCP = jointed plain concrete pavement; GGBFS = ground granulated blast furnace slag|
Figure 61. Layout of test sections 52 and 53 for MN 2 project.
Instrumentation layout for these test sections began in April 2000, with actual construction commencing in June (Mn/DOT 2000). Table 29 summarizes the type and number of sensors in these test sections ( Burnham 2001). Concrete paving was performed on June 30, which was immediately followed by 72 hours of continuous monitoring of the internal shrinkage, strain, and temperatures, as well as the external shape of the slabs (Mn/DOT 2000).
|SENSOR TYPE||MEASUREMENT TYPE||MANUFACTURER||QUANTITIES|
|SECTION 32||SECTION 52||SECTION 53|
|Concrete embedment sensor||Strain||Tokyo Sokki||37||87||20|
|Displacement transducer||Joint opening||Tokyo Sokki||4||8||4|
|Invar reference rod||Elevation||Mn/DOT||4||4|
|Stainless steel reference rod||Elevation||Mn/DOT||2||5||1|
|Concrete embedment sensor||Strain||MicroMeas||8|
|Psychrometer sensor||Relative humidity||Wescor||4||4||4|
|Moisture resistance sensor||Relative humidity||ELE International||6||6||6|
|Dynamic Soil Pressure Sensor||Pressure||Geokon||1||3||3|
|Static soil pressure sensor||Pressure||Geokon||1||2||2|
|Time domain reflectometer||Soil moisture||Campbell Scientific||6||4||4|
|Vibrating wire strain sensor||Strain||Geokon||16||35||34|
As with all pavements at the Mn/Road test facility, these sections are subjected to an intensive data collection effort. In addition to the data obtained from the instrumented slabs within each section, visual distress data, faulting measurements, ride quality, and FWD deflection data are collected (Mn/DOT 2000).
One of the objectives of this study was to evaluate the long-term joint performance of different dowel bar types. Preliminary data on the dowel bars is provided below in Figures 62 and 63. The initial load transfer efficiency was lower for the FRP bars compared to the steel dowels by about 5 percent. After 2 years in service, the load transfer efficiency for the FRP bars dropped from approximately 80 percent to approximately 70 to 75 percent, which are considered critical minimum levels. The performance of the epoxy-coated steel bars appears relatively constant since construction. The differential deflections measured across each joint are still relatively low, as can be seen in Figure 63.
Figure 62. Load transfer efficiency of joints with different types of dowel bars for MN 2 project.
Figure 63. Differential deflections across joints with different types of dowel bars for MN 2 project.
Another objective of the MN 2 project was to evaluate the early-age and long-term slab curling and warping. Early-age profile measurements made using the Dipstick are provided in Figures 64 to 66. The profiles measurements revealed that large positive temperature moments can produce sufficient deformation in the slab such that the slab is unsupported along the whole length of the transverse joint due to upward curvature. Large negative gradients can result in a deformed slab that forces the bottom of the slab into the base layer along the complete length of the transverse joint. The total range of movement of the corner of the slab adjacent to the asphalt shoulder for the temperature conditions present during measurement period was approximately 3,500 microns. The total movement for the corner of the slab adjacent to the longitudinal joint was 2,500 microns. These measurements were for slabs without dowel or tie bars. A more thorough analysis of the early-age performance data can be found in Vandenbossche (2003).
Figure 64. Transverse profile of unrestrained slab in Cell 53 for MN 2 project
Figure 65. Diagonal profile of unrestrained slab in Cell 53 for MN 2 project
Figure 66. Diagonal profile of restrained slab in Cell 52 for MN 2 project
Extensive research has also been performed on the analysis of measured dynamic strains in the thin concrete pavements on the MN2 project. An in-depth discussion of the findings is provided by Burnham (2003; 2004).
1400 Gervais Avenue
Maplewood, MN 55109
Burnham, T. R. 2001. Construction Report for Mn/Road PCC Test Cells 32, 52, and 53 - Final Report. Minnesota Department of Transportation, Maplewood.
---. 2003. "Seasonal Load Response Behavior of a Thin PCC Pavement." Proceedings, Eighth International Conference on Low-Volume Roads, Transportation Research Record 1819. Transportation Research Board, Washington, DC.
---. 2004. "Load Proximity Correlation of Dynamic Strain Measurements in Concrete Pavement." Proceedings, Second International Conference on Accelerated Pavement Testing. Minneapolis, MN.
Minnesota Department of Transportation (Mn/DOT). 2000. New JPCP Test Cells at the Mn/ROAD Project. Minnesota Department of Transportation, Maplewood.
Vandenbossche, J. M. 2003. Interpreting Falling Weight Deflectometer Results for Curled and Warped Portland Cement Concrete Pavements. Thesis for the degree Doctor of Philosophy in Civil Engineering, University of Minnesota, St. Paul.
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