|FHWA > Engineering > Pavements > Concrete > High Performance Concrete Pavements: Project Summary > Chapter 37|
High Performance Concrete Pavements
|11-IN. JPCP 17-20-18-19 FT JOINT SPACING|
|Standard Dowel Layout||Alternative Dowel Layout 1||Alternative Dowel Layout 2||Alternative Dowel Layout 3||Alternative Dowel Layout 4|
|Standard Epoxy-Coated Steel Dowels||Section C1|
|Section 1E||Section 2E||Section 3Ea|
|Solid Stainless Steel Dowels (Avesta Sheffield)||Section 3S||Section 4S|
|FRP Composite Dowel Bars (Creative Pultrusions)||Section CP|
|FRP Composite Dowel Bars (Glasforms)||Section GF|
|FRP Composite Dowel Bars (RJD Industries)||Section RJD|
|Stainless Steel Tubes Filled With Mortar (Damascus-Bishop)||Section HF|
The westbound lanes of the WI 3 project were constructed in June 1997, whereas the eastbound lanes were constructed in October 1997 (Crovetti 1999). The project includes the evaluation of a variable thickness cross section, an alternative dowel bar layout, and alternative dowel bar materials. The variable thickness cross section uses a 275 mm (11 in.) thickness at the outside edge of the outer lane that then tapers to a thickness of 200 mm (8 in.) at the far edge of the inner lane (see Figure 102). The goal is the more efficient use of materials in areas subjected to greater traffic loading, resulting in more cost-effective designs.
Figure 102. Variable cross section used on WI 3.
The following alternative dowel bar materials are also included on the WI 3 project (Crovetti 1999):
The nominal pavement design for these pavement sections is a 275-mm (11-in.) JPCP with a uniform joint spacing of 5.5 m (18 ft). However, as previously described, one section has a variable thickness cross section, varying from 275 mm (11 in.) for the outer lane, and then tapering to 203 mm (8 in.) at the edge of the inner lane. The pavement rests on a 150-mm (6-in.) crushed aggregate base course, and the transverse joints contain 38-mm (1.5-in.) diameter dowels and are not sealed.
Six sections are included in the WI 3 project. The approximate layout of the WI 3 sections being monitored is shown in Figure 103. All dowel bars were placed on baskets prior to paving (Crovetti 1999). It is noted that within the section incorporating various FRP composite dowel bars (Section FR), some of the composite dowel bars were improperly distributed between the 3.7-m (12-ft) and 4.3-m (14-ft) baskets, resulting in different manufacturers' bars being placed across some of the inner and outer traffic lanes (Crovetti 1999). The location of the different manufacturers' dowel bars is shown by lane in the blowup illustration in Figure 103.
Figure 103. Approximate layout of WI 3 monitoring sections.
FRP = fiber-reinforced polymer; JPCP = jointed plain concrete pavement
The experimental design matrix for the WI 3 project is shown in Table 55. Most of the dowel materials are placed in the standard dowel layout, although one section is placed in alternative dowel layout 1. As previously mentioned, all of these sections are included in the SHRP study, and the SHRP code is provided in Table 55 for each section.
|11-IN. JPCP 18-FT JOINT SPACING||8- TO 11-IN. JPCP 18-FT JOINT SPACING|
|Standard Dowel Layout||Alternative Dowel Layout 1||Standard Dowel Layout|
|Standard Epoxy-Coated Steel Dowels||Section C1 (SHRP 550259)||Section 1E (SHRP 550260)||Section TR (SHRP 550263)|
|Solid Stainless Steel Dowels (Slater Steels)||Section SS (SHRP 550265)|
|FRP Composite Bars (MMFG, Glasforms, Creative Pultrusions)||Section FR (SHRP 550264A)|
|FRP Composite Dowel Bars (RJD Industries)||Section RJD (SHRP 550264B)|
|FRP = fiber-reinforced polymer; JPCP = jointed plain concrete pavement|
WisDOT, in conjunction with Marquette University, is monitoring the performance of these pavement test sections. Four types of monitoring activities are used (Crovetti 1999; Crovetti and Bischoff 2001):
Continued monitoring of these sections, in the form of FWD testing, distress surveys, and ride quality surveys, will continue through 2004 (Crovetti and Bischoff 2001).
Even though these sections are only 3 years old, some significant findings have been revealed through their early monitoring. These findings are described in the following sections by type of monitoring activity.
A dowel bar inserter (DBI) was used during the construction of WI 2. The DBI easily accommodated the various types of dowel bar materials used in the study and the various dowel layout patterns with minimal disruption to the paving operations (Crovetti 1999).
With the purpose of determining the depth, longitudinal position, and transverse position of each dowel bar, a dowel bar location study was performed on the WI 2 project 2 months after construction using an impact echo device (Crovetti 1999). A summary of the study results are provided in Table 56 (Crovetti 1999). Generally, it appears that the dowel bars are slightly deeper than the mid-depth of the slab (140 mm [5.5 in.]), and that some vertical skewing of the dowels occurred across the joint. It should be noted that dowel depth data were inconclusive for the stainless steel tubes and the solid stainless steel dowels, and that the device could not provide exact longitudinal and transverse positions of each dowel end (Crovetti 1999).
|TEST SECTION||NO. OF JOINTS TESTED||AVERAGE DEPTH, WEST SIDE OF JOINT, IN.||AVERAGE DEPTH, EAST SIDE OF JOINT, IN.||AVERAGE DEPTH VARIATION, IN.|
|C1 (epoxy-coated steel dowel)||1||6.04||5.86||0.18|
|CP (FRP composite dowel)||2||6.17||5.97||0.21|
|GF (FRP composite dowel)||5||6.12||6||0.47|
|RJD (FRP composite dowel)||7||6.04||6.05||0.2|
|FRP = fiber-reinforced polymer|
FWD testing has been conducted several times since the construction of these test sections. Table 57 summarizes the backcalculated k-value and concrete elastic modulus, as well as the total joint deflection (defined as the sum of the deflections from both the loaded and unloaded sides of the joint) obtained from the FWD testing (Crovetti 1999). Generally, the test results are fairly consistent over time, although greater variability was noticed in the June 1998 tests for both directions, presumably because of higher slab temperature gradients (Crovetti 1999). Apparent increases in total joint deflections may be due to FWD testing conducted in the early morning when upward slab curling is likely.
|PROPERTY||WI 2||WI 3|
|EB LANES||EB LANES||WB LANES|
|Dynamic k-value, lbf/in2/in.||312||255||254||364||324||324||255||222|
|PCC Elastic Modulus, lbf/in2||3,560,000||3,870,000||4,820,000||3,970,000||5,990,000||6,060,000||5,290,000||6,130,000|
|Total 9000-lb Joint Deflection, mils||8.96||7.77||8.18||6.7||5.56||8.48||6.23||7.11|
Transverse joint load transfer efficiencies were also measured on all test sections using the FWD. Figure 104 illustrates the average transverse joint load transfer for the outermost wheelpath of the WI 2 project, while Figure 105 illustrates the average transverse joint load transfer for the outermost wheelpath of the WI 3 project (Crovetti 1999). For WI 2, the late season tests (October 1997 and November 1998) indicate significantly reduced LTE in the composite doweled sections and in dowel layout 1 as compared to the control sections (Crovetti 1999). The LTE measured in the summer do not indicate any significant differences within the test sections, probably because of the increased aggregate interlock brought about by the closing of the joints due to the warmer temperatures (Crovetti 1999). Overall, the low LTE values of the FRP bars (between 60 and 75 percent in many cases) is a cause of concern.
Figure 104. Transverse joint load transfer for outermost wheelpath on WI 2 (Crovetti 1999).
Figure 105. Transverse joint load transfer for outermost wheelpath on WI 3 (Crovetti 1999).
For WI 3, Figure 105 shows that the FRP composite dowel sections and dowel layout 1 experience a reduction in LTE in the November 1998 test results; there is also a slight reduction in the LTE of the stainless steel section (Crovetti 1999). Again, however, the lower LTE values for the FRP bars are a concern.
Distress surveys were conducted for both WI 2 and WI 3 in June and December 1998. Some joint distress (spalling, chipping, and fraying of the transverse joints) was observed and is primarily attributable to the joint sawing operations that dislodged aggregate particles near the joint faces (Crovetti and Bischoff 2001). However, this joint spalling has not yet progressed to the point to be considered as low severity based on the Wisconsin DOT Pavement Distress guidelines (Crovetti and Bischoff 2001). Other than the minor joint spalling, no transverse faulting, slab cracking, or other surface distress has been observed to date (Crovetti and Bischoff 2001).
Figure 106 presents the average international roughness index (IRI) measurements in the outer lane of the WI 2 and WI 3 pavement sections (Crovetti and Bischoff 2001). These measurements were recorded in the summer of 1998 and the winter of 2000. Although there is some variability in the data, most of the test sections are performing comparably to the control sections (Crovetti and Bischoff 2001).
Figure 106. Average IRI values in the outer traffic lanes of WI 2 and WI 3 pavement sections (Crovetti and Bischoff 2001).
Wisconsin Department of Transportation
3502 Kinsman Boulevard
Madison, WI 53704
James A. Crovetti
Department of Civil and Environmental Engineering
P.O. Box 1881
Milwaukee, WI 53201-1881
Crovetti, J. A. 1999. Cost Effective Concrete Pavement Cross-Sections. Report No. WI/SPR 12-99. Wisconsin Department of Transportation, Madison.
Crovetti, J. A., and D. Bischoff. 2001. "Construction and Performance of Alternative Concrete Pavement Designs in Wisconsin." Preprint Paper No. 01-2782. 80th Annual Meeting of the Transportation Research Board, Washington, DC.
|<< Previous||Contents||Next >>|
Office of Asset Management, Pavements, and Construction