|FHWA > Engineering > Pavements > Concrete > High Performance Concrete Pavements: Project Summary > Chapter 6|
High Performance Concrete Pavements
|SIEVE SIZE||PERCENT PASSING|
|150 mm (6 in.)||97 ± 3|
|100 mm (4 in.)||90 ± 10|
|50 mm (2 in.)||45 ± 25|
|75 µm (#200)||5 ± 5|
Pavement designs for the experimental sections consist of both hinge-joint designs and all-doweled designs. As described for IL 1, the hinge-joint design contains conventional doweled transverse joints spaced at 13.7-m (45-ft) intervals and intermediate "hinge" joints containing tie bars at 4.6-m (15-ft) intervals between the doweled joints (see Figure 6). The hinge joints contain number 6 epoxy-coated tie bars, 900-mm (36-in.) long and placed at 450-mm (18-in.) intervals across the joint. The all-doweled designs have transverse joints spaced at 4.6-m (15-ft) intervals and contain dowel bars across every joint. The project has three lanes in the southbound direction (total width of 10.8-m [36-ft]), with the inside and center lanes paved together and the outside lane paved later. A tied curb and gutter was placed adjacent to both the inside and outside lanes.
In addition to pavement design, another variable being evaluated under the study is type of load transfer device. The following five load transfer devices are included (Gawedzinski 1997; Gawedzinski 2000):
Joint width and joint sealant are other variables that are being evaluated under the study. Two of the sections were constructed with 16-mm (0.62-in.) wide transverse joints; these were used on the hinge-joint designs only, and were sealed with preformed elastomeric joint seals conforming to AASHTO M220 (Gawedzinski 2000). The other six sections were constructed with narrow 3-mm (0.12-in.) transverse joints; five of these were sealed with a hot-poured sealant conforming to ASTM D3405 and one section was left unsealed (Gawedzinski 1997).
The layout of the sections is presented in Figure 13. This figure summarizes the main features included in each of the sections. The experimental design matrix for this project is shown in Table 7.
Figure 13. Layout of IL 2 project.
|JRCP HINGE-JOINT DESIGN 45-FT JOINT SPACING||JPCP ALL-DOWELED JOINTS 15-FT JOINT SPACING|
|Preformed Seal (wide joints)||Hot-Poured Sealant (narrow joints)||NoSealant||Preformed Seal (wide joints)||Hot-Poured Sealant (narrow joints)||No Sealant|
|38-mm (1.5-in.) Epoxy-Coated Steel Dowel Bars||Section 1 (270 ft long, 6 doweled joints)||Section 8 (450 ft long, 30 doweled joints)||Section 7 (450 ft long, 30 doweled joints)|
|38-mm (1.5-in.) Polyester and Type E Fiberglass Dowel Bars (RJD Industries)||Section 2 (450 ft long, 10 doweled joints)||Section 3 (210 ft long, 14 doweled joints)|
|44-mm (1.75-in.) Polyester and Type E Fiberglass Dowel Bars (RJD Industries)||Section 4 (225 ft long, 15 doweled joints)|
|38-mm (1.5-in.) Polyester and Type E Fiberglass Dowel Bars (Corrosion Proof Products, Inc.)||Section 5 (150 ft long, 10 doweled joints)|
|38-mm (1.5-in.) Epoxy-Resin and Type E Fiberglass Dowel Bars (Glasforms, Inc.)||Section 6 (150 ft long, 10 doweled joints)|
IDOT collects traffic data for the three southbound and three northbound lanes using two devices:
The Peek 241 uses traditional traffic loop detectors placed in the subbase, with piezo electric axle sensors installed in channels sawed in the surface of the pavement (Gawedzinski 1997). The Groundhog® uses changes in the earth's magnetic field to classify vehicles and requires only a 178-mm (7-in.) diameter hole cored in the new pavement to install the device. However, because problems were encountered with the Groundhog® device no comparisons between the devices are possible (Gawedzinski 2000).
Traffic data for the three experimental southbound lanes are summarized in Table 8 (Gawedzinski 2000). The data are for the period September 25, 1997, to January 31, 2000. The number of ESALs for each lane was estimated by applying the percentage of vehicles in each lane to the total number of ESALs that were reported for all three traffic lanes (1,515,401).
|PROJECT TRAFFIC LANE||TOTAL NUMBER OF VEHICLES||% OF ALL VEHICLES||ESTIMATED ESALS BASED ON VEHICLE %|
|Outside Lane 1||4,687,659||28.6||433,404|
|Middle Lane 2||6,040,237||36.8||557,668|
|Center Lane 3||5,689,235||34.6||524,329|
This project is evaluated by IDOT on at least a semi-annual basis. Evaluation consists of both distress surveys and nondestructive testing using the FWD. Results from the FWD testing program are plotted in Figures 14 and 15 for sections 1 through 6 only (Gawedzinski 2000). Figure 14 shows the average load transfer for the six test sections as a function of time, whereas Figure 15 shows the average maximum joint deflection measured for the sections as a function of time. The best overall load transfer is exhibited by section 1, which contains the conventional steel dowel bars. The other sections all vary from about 70 to 85 percent, but it is interesting to note how the load transfer fluctuates over time, presumably because of the season and temperature at the time of testing. These LTE values are considered marginal, particularly for a pavement that is only a few years old.
Figure 14. Load transfer efficiency on IL 2 (Gawedzinski 2000).
Figure 15. Maximum joint deflections on IL 2 (Gawedzinski 2000).
Figure 15 shows that the maximum deflections for all joints is increasing over time, with the maximum deflection during the October 1999 testing significantly larger for all six sections than the previous maximum deflection values.
After about 3 years of service, this project is performing well. None of the joints is exhibiting any signs of distress. IDOT will continue monitoring the project to assess the relative performance of the different dowel bar types and of the sealed/unsealed joints.
One issue for consideration in future installations of fiber composite dowel bars is the method used to secure the bar to the basket. During construction of the middle and inner lanes of this project, it was noted that the fiber composite bars were loose and only partially attached to the upper support wire of the basket (Gawedzinski 1997). A special metal spring clip provided by RJD Industries was ultimately used to secure the dowel bars to the dowel basket and also to provide an additional frictional force to the bar to prevent it from moving as concrete was placed over the basket (Gawedzinski 1997).
In August 2002, the Model 241 Traffic Classifier was replaced with a Road Reporter manufactured by International Traffic Corporation/PAT America, Inc. Daily traffic files are polled periodically and tabulated to provide monthly traffic totals for classification. Standard conversion factors used by are used to convert single unit (SU) and multiple unit (MU) truck counts to ESALs. In May 2003, land development work on the properties on the east side of IL 59 resulted in an east-west access road intersecting IL 59 at the location of the traffic classifier loops and piezo sensors. Traffic signals associated with the new road necessitated relocating the traffic classifier site approximately 0.6 km (0.4 mi) to the south. Work on relocating the site will be complete in 2004. Cumulative ESAL information for each lane, as reported by the Illinois Department of Transportation (Gawedzinski 2004), are provided in Table 9.
|DATE||CUMULATIVE ESALS RIGHT LANE||CENTER LANE||LEFT LANE|
FWD tests are currently performed annually across all of the test sections. Certain sections were dropped from the FWD testing for a time due to traffic safety issues. These issues were resolved, and now FWD results are obtained for both wheelpaths and the center of the lane for all three lanes. Visual observations of joint performance are performed periodically, noting any changes in the appearance of the pavement. Results of the FWD tests are provided in Figures 16 through 18 for the right, center, and left lanes, respectively.
Figure 16. Load transfer efficiency vs. ESALs for the right lane (Gawedzinski 2004).
Figure 17. Load transfer efficiency vs. ESALs for the center lane (Gawedzinski 2004).
Figure 18. Load transfer efficiency vs. ESALs for the left lane (Gawedzinski 2004).
Evaluation of the joints shows typical behavior of the joints and the joint sealer/filler material with no obvious signs of spalling or faulting. The preformed elastomeric joint sealer remains intact, while the ASTM D-6690 (formerly ASTM D-3405) material is acting more as a joint filler in that there are areas across several joints where the material has become debonded from the pavement, allowing water and incompressibles into the joint.
Observations of the LTE vs. time and ESALs graphs, as well as the joint deflection vs. time and ESALs graphs, show somewhat consistent behavior for joint deflection, with sections averaging 3 to 5 mils. The LTE graphs show behavior consistent with a decrease in joint deflection. Figure 19 shows the same type of behavior displayed at the Williamsville test site (IL 1). Plots of average values show no relationship between LTE or joint deflection and average pavement temperature. The control bars (38.1-mm [1.5-in.] diameter epoxy-coated carbon steel) have a higher LTE and lower joint deflection than any of the fiber composites, but the overall performance of the fiber composite bars appears to be very close to the behavior of the epoxy-coated steel control set. Nevertheless, LTE values on the order of 70 to 80 percent after only a few years of service may suggest that the FRP bars are not suitable for long-term performance.
Figure 19. Average load transfer efficiency vs. pavement temperature for all lanes (Gawedzinski 2004).
Illinois Department of Transportation
Bureau of Materials and Physical Research
126 E Ash Street
Springfield, IL 62704
Gawedzinski, M. 1997. Fiber Composite Dowel Bar Experimental Feature Construction Report. Illinois Department of Transportation, Springfield.
---. 2000. TE-30 High Performance Rigid Pavements Illinois Project Review. Illinois Department of Transportation, Springfield.
---. 2004. TE-30 High Performance Concrete Pavements: An Update of Illinois Projects. Illinois Department of Transportation, Springfield.
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