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Arrow Utah Demonstration Project: Precast Concrete Pavement System on I-215

Project Details

Background

I-215 is a busy interstate belt route southeast of Salt Lake City. The HfL project was conducted on the SB lanes of I-215 in the vicinity of the entry ramp from 3900 South. The general project location is shown in Figure 1. Here, the SB direction of I-215 has three lanes, and a shoulder, as seen in Figure 2. A portion of the project also includes a merge area, as seen in Figure 2.

Figure 1. Location of project on I-215 southeast of Salt Lake City.

Figure 1. Location of project on I-215 southeast of Salt Lake City.

 

Figure 2. Photo. The functionally obsolete existing structure.

Figure 2.Project location and plan on southbound I-215.

 

Figure 3. Photo. Southbound project view showing three lanes, merge area, and shoulder.

Figure 3. Southbound project view showing three lanes, merge area, and shoulder.

The 2009 average daily traffic for this section was 68,000 (in two directions), which includes a mix of commuter and truck traffic. The a.m. hourly peak was close to 4,500 vehicles, and the p.m. hourly peak was close to 2,500 vehicles in the SB direction alone. This is also a major route to Salt Lake City International Airport and a major truck route for SB traffic from I-80 to I-15. The relatively high peak hour urban traffic volumes make long-term lane closures highly disruptive, so UDOT sought to minimize the impact of construction on traffic.

The pavement was in poor condition when measured in 2008. The existing nondoweled concrete pavement was constructed in 1976 and was well beyond its 20- to 30-year design life. Pavement repairs had not been made since original construction. The existing concrete pavement also showed signs of surface polishing and cracking and corresponding reduction in skid resistance. UDOT estimated that about 1,500 square yards required full-depth replacement, which would cause enormous disruptions to traffic if performed traditionally. The pavement condition was assessed as fair. Pavement joints had debris and missing materials, which also contributed to cracking and spalling. Figures 3 through 7 show the pavement condition in May 2011.

Figure 4. Photos. Shattered slabs with longitudinal and transverse cracking on I-215.

Figure 4. Photos. Shattered slabs with longitudinal and transverse cracking on I-215.

 

Figure 5. Photo. Map. High-severity spalling and polishing of PCC surface on I-215.

Figure 5. Map. High-severity spalling and polishing of PCC surface on I-215.

 

Figure 6. Photo. High-severity cracks and spalls on the on-ramp slabs on I-215.

Figure 6. High-severity cracks and spalls on the on-ramp slabs on I-215.

 

Figure 7. Photo. Severely deteriorated cracks and spalls filled with HMA on I-215.

Figure 7. Photo. Severely deteriorated cracks and spalls filled with HMA on I-215.

Project Description

The innovation on this project was the use of APC techniques, specifically PCPS. UDOT chose to use precast pavement panels with a placement time of 7 to 10 hours. Using precast pavements allowed for offsite construction with a better cure environment and offpeak construction, compared to traditional cast-in-place construction with a minimum 7- to 10-day cure time and limited control of the cure environment.

UDOT's goals for using APC were the following:

  • Minimize traffic impacts by performing concrete curing offsite.
  • Use an improved cure environment with greater control of temperature, moisture, and cure time.
  • Reduce traffic disruptions from 7 to 10 days per panel to 7 to 10 hours.
  • Allow for offpeak construction with normal operations during normal traffic.
  • Minimize traffic impacts by reducing the overall construction schedule.
  • Improve construction zone safety by minimizing exposure time for workers and the traveling public.
  • Make the pavement replacement more constructible by working around difficult constraints.
  • Enhance the design quality by reducing dependence on weather and increasing the control of the quality of elements and systems.
  • Reduce traffic control costs by minimizing construction time.
  • Maximize the functional use of this vital corridor.

Using APC to address the pavement deficiencies and the knowledge and abilities of the contractor and designer, UDOT hoped to achieve best-value improvements. UDOT considered the use of PCPS for rapid repair because it is a technology that could improve safety, reduce congestion, and improve pavement performance, all of which are key elements of the HfL program.

  • Safety: UDOT expected that APC use would improve work zone safety primarily because of the reduction in construction time and exposure of workers and motorists to work zone hazards. In addition, APC use would allow for offpeak construction when traffic volumes are lower, which was also expected to reduce the potential for crashes.
  • Construction congestion: Normal construction would require phasing traffic with cure times of 7 to 10 days. The use of APC was expected to reduce this to 7 to 10 hours per panel, leading to a 90 percent reduction in construction time. With the use of precast panels, it was expected that the majority of work could be performed at night during offpeak hours. Once the panels were placed, the road would be opened to traffic the next day. Thus, the use of precast pavement panels with nighttime construction would allow all traffic lanes to be open during daytime, particularly peak, hours because of the absence of traditional cure times.
  • Quality: The project performance goal was to meet or exceed the more restrictive requirement of either the IRI or UDOT’s standards. The project also included diamond grinding of the existing concrete pavement, which was expected to reduce tire-pavement noise. However, this reduction would not be because of APC use, but the grinding itself.
  • User satisfaction: UDOT performs a pre-, mid- and postconstruction survey using a 1 to 7 scale to measure user satisfaction on major elements affecting stakeholders at various intervals during any major project. On this project, UDOT’s goal was to receive an average score of 4-plus on the postconstruction survey on how satisfied the user is with the new facility compared with its previous condition and how satisfied the user is with the approach used to construct the new facility in terms of minimizing disruption. UDOT used the mid- and preconstruction surveys as indicators of where and how to do a better job for stakeholders to reach the goal of 4-plus on the postconstruction survey.

UDOT's goal for the project was to demonstrate how APC technologies can be used to reduce construction impacts while improving safety and durability. UDOT planned to use APC with other programs, such as accelerated bridge construction. HfL's promotion of PCPS as a Vanguard Technology encouraged UDOT to submit an HfL project application.

Design Decisions

The design for the project began with a scanning study of other States with experience using PCPS, followed by a lessons-learned report. A brainstorming meeting was held with UDOT engineers, fabricators, consultants, and contractors to discuss lessons learned from the scanning study. Based on the lessons learned and the meeting, the concept plans and work approach were developed. Six test panels were placed in fall 2010 for evaluation over the winter. Lessons learned from placement of the test panels were used to modify and improve plans for placement of the I-215 panels. Key design challenges included the following:

  • Geometry and fit
  • Lifting of panels (weight, devices, etc.)
  • Leveling of panels, base preparation, and profile
  • Grout materials
  • Load distribution and transfer between panels

Geometry and Fit

Geometry and fit were important technical issues that needed to be resolved, particularly with a curved horizontal alignment. Curved horizontal alignment creates potential for fit issues with an estimated calculated chord offset as high as 0.25 in. A key question was whether to use curved or straight panels. The decision was made to use 12-foot (ft) straight panels rather than curved panels, vary the joint width, and saw cut and grout as needed. This was done with a goal to develop standardized sizes and shapes and to have flexibility for starting and stopping points of the project. Another issue considered during design was that the existing longitudinal joint would be irregular after removal of the old PCC, creating potential fit problems. The decision was made to saw cut the existing longitudinal joint to improve the fit between the lane 2 pavement and the new lane 3 panels. During construction, some of the new panels were also saw cut to improve fit.

Lifting of Panels

Key decisions needed to be made to reduce stresses and potential cracking of the panels during transportation, lifting, and placement. The panels were reinforced with #4 deformed steel bars to support panel weight during lifting. Reusable swivel lifting devices used for heavy loads were specified. These lifting devices have angular load capacity because of the swivel, and a smaller hole is needed for the swivel lifting devices compared to conventional lifting bolts.

Grade Preparation and Profile Leveling

Decisions on grade preparation and profile leveling were made with a goal to minimize the time spent preparing the grade and placing panels because of the short nighttime timeframe (7- to 10-hour closures) to remove and replace the existing pavement. Decisions were made to adjust the panel elevation using leveling screws, eliminate the sand bed, and use urethane or concrete grout injection under the panels to provide uniform support to the panels.

Grout Materials

Grout was specified to be pumped in the grout ports of the panels to flow between the panel and the base material, filling voids and providing uniform support to the panels. Prototype tests showed 100 percent coverage for both urethane and concrete grout options. Field tests showed that both materials performed well over the winter. The decision made was that both materials were acceptable. However, urethane was chosen for this project because of its shorter cure time.

Load Transfer Devices

The existing pavement does not have load transfer at the joints. A key design question was whether load transfer devices (dowel bars) were needed and whether they would damage the adjacent panels. The decision made was to use 1.5-in × 18-in dowel bars at transverse joints (six for the 12-ft × 12-ft slabs and three for the 6-ft × 12-ft slabs) and to saw cut the dowel bar slots and joint sealant reservoir after placement of the panels for better alignment and to avoid fit problems.

Design Details

Figure 8 is a typical cross-section showing the transverse view and the side view of the PCPS slab. As shown in the figure, two sizes of panels (49 12 ft × 12 ft and seven 6 ft × 12 ft) were used on this project. The 12-ft × 12-ft panel was used on lane 3, while both 12-ft × 12-ft and 6-ft × 12-ft panels were used in the merge area of the on-ramp to SB I-215.

 

Figure 8.  Diagram. Transverse View of the PCPS.
Diagram. Side View of the PCPS

Figure 8. Transverse view and side view showing the PCPS slab panels to be placed.

Figure 9 and Figure 10 show the typical plan views and section views for the 12-ft × 12-ft panels and the 6-ft × 12-ft panels, respectively. The key features of the PCPS panels are summarized as follows:

  • The 9-in thick panels are placed on untreated base course fill material with as-required thickness, which is placed directly over the existing subgrade.
  • A urethane leveling grout is pumped in through nine grout injection holes in the 12-ft × 12-ft panels and three grout injection holes in the 6-ft × 12-ft panels. The leveling grout levels the PCPS panels above the base course fill material. The thickness of the leveling grout varies depending on the amount of grout needed for leveling. A preformed strip seal is used on all sides to prevent the grout from seeping out.
  • The 12-ft × 12-ft panels consist of six dowel bar slots (three in each wheelpath), as shown in Figure 9, and the 6-ft × 12-ft panels consist of three dowel bar slots, as shown in Figure 10. Details of the dowel slots and load transfer device (dowel bar) placement are shown in Figure 11. The figure shows that the slots from two adjacent panels are aligned for placement of the 18-in long, 1.5-in diameter smooth dowel bar. The dowel bars are supported by the rebar chairs (0.5 in high), which are placed directly in the bottom of the slot. The rebar chairs ensure that the dowels rest horizontally and parallel to the centerline of the pavement at the desired depth. Expansion caps are placed at both ends of the dowel to allow for any joint closure after installation of the dowel. The length of the dowel bar slot is 1 ft in each of the panels corresponding to a total slot length of 2 ft, which provides for a 3-in clearance on both sides of the dowel bar. Each slot is 3 in wide and 4.5 in deep. After the dowel bar is placed, the slot in each panel is filled with load transfer grout, which completely encompasses the bar on each side of the transverse joint. A filler board or expanded polystyrene foam material is placed at the midlength of the dowel to help form the joint in the slot and prevent intrusion of the grout into the joint between the two panels.
  • Four lift points are used for each panel at the four corners of the panels. Each lift point is 2 ft from the longitudinal edge and 2 ft from the transverse edge of the panel. A Dayton Superior T-26 lifting swivel with B-14 coil and T-1 insert was specified to be used for lifting. Detail of the T-26 lifting swivel is shown in Figure 12.
  • The panels include four holes for leveling bolts at the four corners. Each hole is 1.5 ft from the longitudinal edge and 1.5 ft from the transverse edge of the panel. Details of the leveling bolt are shown in Figure 13. Each leveling bolt is placed on top of 6-in × 6-in × 0.25-in leveling plates. The 1-in diameter coil rod bolt screws into the coil rod nut and 4-in × 4-in × 0.25-in washer that is cast in the panel. The action of screwing and unscrewing the coil rod bolt onto the surface of the leveling plate raises and lowers the corresponding panel corner. Leveling gauges on the panel surface are used to ensure that the panels are level. Once a panel is level, it is grouted to the base to fill all voids and ensure even support. The coil rod bolt is removed and the bolt holes grouted after urethane grout is set.
  • The panels are constructed with steel reinforcement (#4 bars spaced at 12 in) placed with 2-in clearance from the bottom of the panels. The purpose of the steel reinforcement is to prevent breaking of the slab during transportation, lifting, and installation.

 

Figure 9. Diagram. Typical plan view and section view for 12-ft × 12-ft panels.

9. Typical plan view and section view for 12-ft × 12-ft panels.

 

Figure 10. Photo. Typical plan view and section view for 6-ft × 12-ft panels.

Figure 10. Typical plan view and section view for 6-ft × 12-ft panels.

 

Figure 11. Diagram. Load transfer device details.
Figure 11. Diagram. Load transfer device details Section A-A

Figure 11. Load transfer device details.

 

Figure 12. Diagram. Lifting device details.

Figure 12. Lifting device details.

 

Figure 13. Leveling bolt detail.

Figure 13. Leveling bolt detail.

Construction

The construction project was awarded to Kilgore Contracting and the precast panels were made by Harper Precast. The I-215 construction project included replacing distressed pavement slabs with precast concrete pavement panels. Figures 14 through 17 show the casting of the precast panels at Harper Precast. The panels were placed during a 7- to 10-hour nighttime window with closure of the rehabilitated lane and the adjacent lane. The third lane (lane 1) was open to traffic throughout the construction. All lanes were open to traffic during daytime hours. Special provisions required the following:

  1. No work will be allowed before May 1, 2011.
  2. All paving operations must be completed by May 31, 2011 (this deadline was changed allowing for work in June).
  3. Temporary HMA asphalt paving may be used at the end of each day’s work to transition concrete panel replacement with existing pavement.
  4. The contractor will be required to obtain noise and other permits and perform work within those limitations.
  5. Traffic control setup will be allowed to start at 7:30 p.m. daily (Monday through Sunday).
  6. A single lane closure will be allowed daily (Monday through Sunday) beginning at 8 p.m.
  7. Two lanes will be allowed for closure daily (Monday through Sunday) beginning at 10 p.m.
  8. Two lanes of traffic must be open by 6 a.m. on weekdays (Monday through Friday).
  9. All three lanes of traffic must be open by 6:30 a.m. on weekdays (Monday through Friday).
  10. Two lanes of traffic must be open by 7 a.m. on weekend days (Saturday and Sunday).
  11. All three lanes of traffic must be open by 9 a.m. on weekend days (Saturday and Sunday).
  12. Conduct work to minimize lane closures. Maintain communication with UDOT Traffic Operations Center during lane closures.
  13. Lane closures beyond allowable timeframes will result in a lane rental charge of $15,000 per lane per hour.

Table 1 shows the contractor’s nightly activity schedule

Table 1. Nightly activity schedule.
Approximate Time Activity
7–7:30 p.m Close ramp and lane 3; place barrier
7:30–9 p.m Remove existing panels
8:30–10 p.m Prepare grade
9:30 p.m.–3 a.m Set panels
10:30 p.m.–3:30 a.m Inject urethane
3:30–6 a.m Stripe, clean up, and remove barrier
6 a.m. Open travel lane.

After lane closures, barrier placement, mobilization, and preparation, the project started with removal and hauling of the existing pavement (lane 3), as shown in Figure 18 and Figure 19. Note the jagged longitudinal edge of the existing pavement (lane 2) in Figure 18. These longitudinal edges were saw cut for better panel fitting and grout containment, as shown in Figure 19. Per specifications, the existing base material was excavated, repaired, regraded, and compacted with a vibrating plate compactor, as shown in Figure 20. The base was specified to be finished with plus or minus 0.5 in of the desired profile. Sand bedding material was used to fill void areas as needed. The leveling plates were placed directly on the prepared compacted base, as shown in Figure 21. The panels were moved into place using a crane and supported at four points using lifting swivels, as shown in Figure 22 and Figure 23. A field decision was made to taper cut some of the panels (Figure 24) by 1 to 1.5 in to account for the horizontal curvature of the existing roadway.

Once the panels were placed on the prepared base, they were leveled using leveling bolts to within final grade tolerance of 0.25 in, as shown in Figure 25 and Figure 26. Preformed strip seal was used to seal the longitudinal joint and prevent grout from flowing out of these joints, as shown in Figure 27. Urethane leveling grout was injected through the grout injection hole, as shown in Figure 28 and Figure 29, to fill voids and support the panels. The urethane grout was specified to develop 90 percent of its full compressive strength of 90 pounds per square inch within 30 minutes of injection at 40º F or greater. The leveling bolts were specified to be removed or field cut at a minimum of 1 in below the top surface of the panel. Lifting block-outs, grout ports, and leveling bolt hardware block-outs were repaired using specified cement grout. Longitudinal or transverse joints in excess of 0.5 in were filled with specified encasement grout. Dowel slots were cut in at the transverse joints to retrofit the panels with dowel bars, as shown in Figure 30 and Figure 31. The final constructed project is shown in Figure 32.

Figure 14. Photo. Completed form ready for concrete pour.

Figure 14. Completed form ready for concrete pour.

 

Figure 15. Photo. Pouring concrete in form to precast the panel.

Figure 15. Pouring concrete in form to precast the panel.

 

Figure 16. Photo. Removal of grout tube and bolt locator jigs.

Figure 16. Removal of grout tube and bolt locator jigs.

 

Figure 17. Photo. Finished top of precast panel ready for curing.

Figure 17. Finished top of precast panel ready for curing.

 

Figure 18. Photo. RRemoval of existing deteriorated pavement (lane 3).

Figure 18. Removal of existing deteriorated pavement (lane 3).

Figure 19. Photo. Hauling of existing pavement (lane 3).

Figure 19. Hauling of existing pavement (lane 3).

 

Figure 20. Photo. Placing and compacting the base course fill material.

Figure 20. Placing and compacting the base course fill material.

 

Figure 21. Photo. Leveling plates placed directly on top of the compacted base.

Figure 21. Leveling plates placed directly on top of the compacted base.

 

Figure 22. Photo. Placement of precast panel on the prepared base.

Figure 22. Placement of precast panel on the prepared base.

 

Figure 23. Photo. Removal of grout tube and bolt locator jigs.

Figure 23. Steering precast panel into place onto the prepared base.

 

Figure 24. Photo. Removal of grout tube and bolt locator jigs.

Figure 24. Cutting panels to 1- to 1.5-in taper to account for horizontal curvature of existing roadway.

 

Figure 25. Photo. Leveling bolts used to level the panels on the leveling plates.

Figure 25. Leveling bolts used to level the panels on the leveling plates.

 

Figure 26. Photo. Removal of grout tube and bolt locator jigs.

Figure 26. Panels leveled using leveling bolts to within final grade tolerance of 0.25 in.

 

Figure 7. Photo. Construction detail of innovative bare deck design with flush-mounted rail.

Figure 27. Placing preformed strip seal to contain grout.

 

Figure 28. Photo. Urethane grout injected through the grout injection hole.

Figure 28. Urethane grout injected through the grout injection hole.

 

Figure 29. Photo. Urethane grout injected through the grout injection hole.

Figure 29. Urethane grout injection closeup.

 

Figure 30. Photo. Placement of dowel bars into dowel slot.

Figure 30. Placement of dowel bars into dowel slot.

 

Figure 31. Photo. Transverse joint with grout-filled dowel bar slots.

Figure 31. Transverse joint with grout-filled dowel bar slots.

Figure 32. Photo. Placed panels and project open to traffic before diamond grinding for ride quality.

Figure 32. Placed panels and project open to traffic before diamond grinding for ride quality.

 

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Contact

Mary Huie
Highways for LIFE
202-366-3039
mary.huie@dot.gov

Updated: 05/30/2013

FHWA
United States Department of Transportation - Federal Highway Administration