Guide to Using Existing Pavement in Place and Achieving Long Life (2014)

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350 INTRODUCTION There are portland cement concrete (PCC) and fl exible pavement technologies that cannot, as yet, be considered long-life renewal options but may become so in the future. One technology reviewed, precast concrete pavement, is likely a long-lasting renewal option at this time. The limitation is that there are few projects under traffi c to make that type of assessment. Thus, the term “emerging pavement technologies” does not necessarily imply that the concept is new. Several of these promising technologies were selected for a brief overview and include the following: • Rigid pavements — Ultrathin continuously reinforced concrete pavement (CRCP) overlays — Precast concrete pavement • Flexible or composite pavements — Resin-modifi ed pavement Without doubt, there are other technologies that could be featured; however, this is not the primary purpose of this study. This short treatment simply suggests that technologies exist that should be monitored as they continue to evolve and which may be or may become viable components for long-lasting pavement renewal. RIGID PAVEMENTS Ultrathin CRCP Overlays (UTCRCP) This innovative pavement rehabilitation treatment was fi rst reported in 2004 as an overlay system for steel bridges. This technology is not to be confused with ultrathin fi ber-reinforced concrete overlays, which have been more widely evaluated in the United 6 EMERGING PAVEMENT TECHNOLOGY

351 EMERGING PAVEMENT TECHNOLOGY States (such as the examples provided by Kuo, Armaghani, and Scherling, 1999). The UTCRCP approach has been extensively investigated in South Africa (Kannemeyer et al., 2008). Figure 6.1 illustrates some of the heavy vehicle simulator (HVS) testing that was recently completed for UTCRCP test sections near Johannesburg. The South African experimental sections were mostly 50-mm thick and placed on various bases ranging from hot-mix asphalt (HMA) to natural gravel. Continuous steel mesh was used for reinforcement along with two types of steel fibers (straight and hooked). The continuous reinforcement as a percentage of the cross-sectional area is higher than for traditional CRCP—about 1.0% as opposed to typical values of 0.6% for CRCP. For the recent test conditions that used a granular base, it is estimated that a 50-mm UTCRCP has a minimum life of 25 million equivalent single axle loads (ESALs). Kannemeyer et al. estimated that this type of overlay would last between 14 and 55 years, depending on average daily truck traffic. (Kannemeyer et al. assumed that each truck applied 5 ESALs/truck.) A 50-mm UTCRCP overlay was placed on the N12 highway in Johannesburg (project completion date November 2010) along with 200-mm CRCP in the slow lanes. The UTCRCP was placed on the “fast” or inside lanes for these multilane high- ways. The underlying base is HMA. Two types of reinforcement were used on the project: (1) a wire diameter of 5.6 mm with a 100 mm by 50 mm spacing, and (2) a wire diameter of 4 mm with a 50 mm by 50 mm spacing. A second UTCRCP project was constructed on the N1 highway northeast of Paarl (near Cape Town), South Africa (Figure 6.2). This project currently serves 12,000 vehicles per day with 20% trucks (Ebels and Burger, 2010) and serves as a climbing lane. The design loading is 40 million E80s over a 25-year span and it has a 50-mm thickness. The mix makes use of polypropylene fibers, 5.6-mm-diameter steel mesh with a spacing of 50 mm by 100 mm, maximum nominal size aggregate of 6.7 mm, and various admixtures. This results in a mix with a compressive strength of about 15,000 psi and a minimum flexural strength of 1,500 psi. Potential for Long-Term Performance The South African experience with UTCRCP should be monitored because it has been carefully assessed by use of HVS experiments and is now deployed on actual highways. Precast Panels and Precast Prestressed Concrete Pavement (PPCP) PPCP Case Studies Several precast concrete pavements have been built in the United States over the past 10 years; three well-documented projects include locations in Texas (completed in 2001), California (completed in 2004; Merritt, McCullough, and Burns, 2005), and Minnesota (completed in 2005; Burnham, 2007). Subsequently, projects have been completed in Missouri (2005) and Iowa (2006; Federal Highway Administration, 2009). The purpose of these projects was to assess the viability of precast concrete pavements for rapid construction and rehabilitation. These projects are relatively short. The longest is the Texas I-35 frontage road project at 2,300 ft. The Caltrans I-10 project was 248 ft, the Missouri project 1,010 ft, and the Iowa project 4,300 ft2.

352 GUIDE TO USING EXISTING PAVEMENT IN PLACE AND ACHIEVING LONG LIFE (a) (b) (c) (d) (e) (f) Figure 6.1. Thin CRCP being tested via the heavy vehicle simulator in South Africa. (a) Testing of thin CRCP near Heidelberg, South Africa. (b) HVS testing of 50-mm thin CRCP. (c) Testing includes substantial instrumenta- tion for in situ measurements. (d) HVS testing typically continues until a failure condition is reached. (e) Previously tested section illustrating reinforcing. (f) Close-up of reinforcing. Photos: Joe Mahoney.

353 EMERGING PAVEMENT TECHNOLOGY Figure 6.2. UTCRCP on the N1 Highway near Cape Town, South Africa. Photos: Wynand Steyn. Earlier projects built in South Dakota, Japan, and Texas were documented by Merritt et al. (2000). The earliest Texas project was built in 1985 as a 6-in.-thick cast-in-place prestressed pavement. Merritt et al. (2000) noted that for thickness design a reasonable lower limit for precast panel thickness would not be less than 50% to 60% of conventional con- crete pavement. An analysis comparing a precast concrete pavement versus a more tradi tional CRCP suggested that 14-in.-thick CRCP would be equivalent to 8-in.-thick precast concrete panels. It was also noted that the 6-in. Texas-built cast-in-place pre- stressed pavement exhibited no distress following 15 years of in-service traffic. The concept for the 2001 Texas project was stated as follows: “to develop a concept for a precast concrete pavement—one that meets the requirements for expe- dited construction and that is feasible from the standpoint of design, construction, economics, and durability. The proposed concept should have a design life of 30 or more years to make it comparable to conventional cast-in-place pavements currently being constructed” (Merritt et al., 2000). This project, as noted earlier, was 2,300 ft long with panels either 10 ft by 20 ft or 10 ft by 36 ft, all 8 in. thick (Federal Highway Administration, 2009). The posttensioned sections were 7 at 250 ft, 1 at 225 ft, and 1 at 325 ft. The panel installation rate was 25 panels per 6 hours. Figure 6.3 provides an aerial view of the project and Figure 6.4 shows photos taken during December 2010 to illustrate performance to date. The pavement was 9 years old at the time the photo- graphs were taken and at the time exhibited no distress other than a few tightly closed longitudinal cracks. It should be noted that this road receives limited heavy traffic. The 2004 Caltrans project used 8-ft precast panels, which resulted in a total of 31 panels to achieve the 248-ft length. The panel thicknesses were 10 in.—a thickness required to match an existing pavement. Each panel weighed 21.5 tons, which limited delivery to one panel per truck cycle to the job site. The expansion joints were designed

354 GUIDE TO USING EXISTING PAVEMENT IN PLACE AND ACHIEVING LONG LIFE for an opening ≤1 in. The panel installation rate was 15 panels over 3 hours. It was estimated that the design life would range from 30 to 57 years. The total in-place cost of this project was $224/yd2. The 2005 Missouri project was built on I-57 near Sikeston. The project length was 1,010 ft (two lanes plus shoulders), which used 10 ft by 38 ft panels ranging from 5.75 to 11.0 in. thick (the thinner sections are associated with the shoulders). The postten- sioned sections were 4 at 250 ft. The panel installation rate was 12 panels per 6 hours. The precast panels were placed on a 4-in.-thick permeable asphalt base. Precast Panels Precast panels were used to replace a short section of jointed reinforced concrete pave- ment (JRCP) in Minnesota. The project was built on Trunk Highway (TH) 62 during June 2005 in the vicinity of the Minneapolis–St. Paul International Airport (Burnham, 2007). The original pavement was 8-in.-thick JRCP. Joint repairs were made in 1986, but the pavement was in need of additional rehabilitation about 20 years later. In 2005, TH-62 had concrete rehabilitation repairs made, along with the addition of Figure 6.3. PPCP section: Texas I-35 frontage road.

355 EMERGING PAVEMENT TECHNOLOGY a precast test section (Figure 6.5). The precast test section was 216 ft long by 12 ft wide, which required 18 panels (the Fort Miller Co. precast system). Each panel was 12 ft long by 12 ft wide by 9.25 in. thick. The precast panels were not tied to the adjacent JRCP lane, nor were they posttensioned; rather they were doweled at the transverse joints. The test section was ground about 5 months after construction with the international roughness index (IRI) results summarized in Table 6.1. Load transfer efficiency measurements for the transverse joints were about 90% to 95% one year after construction. TABLE 6.1. SUMMARY OF IRI RESULTS FOR PRECAST PANELS, MINNESOTA TH-62 Time and Activity Average IRI for Both Wheelpaths (in./mi) TH-62 before construction 150 New precast panels (Fall 2005) 140 After grinding panels (Fall 2005) 76 Six months following grinding (April 2006) 50 Source: After Burnham, 2007. Figure 6.4. PPCP section, Texas I-35 frontage road, December 2010. Photos: Joe Mahoney. Typical longitudinal crack. Longitudinal crack (close-up).

356 GUIDE TO USING EXISTING PAVEMENT IN PLACE AND ACHIEVING LONG LIFE Potential for Long-Term Performance Precast concrete pavements show significant promise. Tracking performance of the existing pavements is needed. Cost and construction times will likely drop as larger projects are constructed. FLEXIBLE OR COMPOSITE PAVEMENTS Resin-Modified Pavement (RMP) RMP was described by Ahlrich and Anderton (1991) as a “semi-rigid, semi-flexible” surface course. It is an open-graded HMA layer with about 25% to 30% air voids, which are filled with a resin-modified cement slurry grout. As noted by Ahlrich and Anderton, “RMP is a tough and durable surfacing material that combines the flexible characteristics of an asphalt concrete material with the fuel, abrasion, and wear resis- tance of a portland cement concrete.” The original concept for RMP was developed in Europe during the 1960s. The basic process for RMP is as follows (after Ahlrich and Anderton, 1991): 1. Place an open-graded HMA layer. This layer determines the thickness of the RMP. 2. Pour the grout material (portland cement, fine aggregate, water, and a resin addi- tive) onto the HMA, squeegee over the surface, and vibrate into the voids with a small vibratory roller. 3. Cure the grout material with standard white-pigment sprayed curing compound. Precast Panels JRCP Lane Figure 6.5. Precast section, Minnesota TH-62. Source: Burnham, 2007.

357 EMERGING PAVEMENT TECHNOLOGY Ahlrich and Anderton (1991) reported accelerated pavement testing by use of the FHWA ALF device at Turner Fairbank. The trafficking used dual tires loaded to 19,000 lb with tire pressure of 140 psi. Following 80,000 passes, the RMP surface performed well with no deterioration. At the time of U.S. Army Corps of Engineers testing, the cost of RMP ranged between that of traditional HMA and that of PCC. More recent studies on RMP include a 5-year performance assessment by Bat- tey and Whittington (2007) in Mississippi (see construction of RMP, Figure 6.6). Three systems were assessed for use in signalized intersections on US-72 in Corinth, Mississippi: 1. RMP wearing course 2 in. thick, 2. Ultrathin whitetopping 3 in. thick, and 3. HMA overlay with PG 82-22 binder. The comparison of these three options was assessed following 5 years of service. The order of comparison revealed the overall best option was the PG 82-22 HMA overlay, followed by the ultrathin whitetopping, and RMP last. However, the assess- ment also showed that the RMP exhibited no rutting but was the most expensive. The ultrathin whitetopping began to crack after 2 years of service and was eventually removed from service. RMP is also being evaluated in South Africa. The photos shown in Figure 6.7 were taken in 2009 of a RMP that had been in service for 2 years at a truck weigh station (whereby all traffic involves trucks moving at a slow speed). As of 2009, no rutting or significant cracking had occurred. Figure 6.6. Construction of RMP. Application of the grout to the open-graded HMA. Source: Battey and Whittington, 2007.

358 GUIDE TO USING EXISTING PAVEMENT IN PLACE AND ACHIEVING LONG LIFE Potential for Long-Term Performance RMP appears to be a system appropriate only for wearing courses (largely due to cost and construction challenges). The performance appears quite good, particularly with regard to rutting resistance, but whether RMP will outperform traditional dense- graded HMA is as yet unclear. Hopefully, those that have built this type of pavement will continue to monitor performance and report their findings. COST COMPARISONS Cost comparisons for emerging technologies are a challenge on several levels because of their use in experimental projects, limited production, exchange rates, etc. Further- more, materials and construction costs for pavements are rather volatile along with elusive, up-to-date national statistics. As such, background based on costs obtained from the Washington State Department of Transportation (WSDOT) for asphalt concrete and concrete paving materials are shown below (costs as of September 2010; WSDOT, 2010), along with available data from other projects (see Table 6.2). Table 6.3 provides performance lives and cost estimates for typical preservation treat- ments, developed as part of the SHRP 2 R26 study, which provide additional cost perspectives. SUMMARY The three emerging technologies illustrated in this document are only a sample of promising pavement developments. Whether the concepts illustrated ultimately con- tribute widely to long-lasting renewal options is yet unclear. On a national basis, sys- tematic reporting on these types of technologies is needed (along with others yet to be identified). (a) (b) Figure 6.7. Resin-modified pavement. (a) Resin-modified pavement at a truck weigh station on the N3 near Johannesburg, South Africa. (b) Close-up of the resin-modified cement that was placed on open-graded HMA. Photos: Joe Mahoney.

359 EMERGING PAVEMENT TECHNOLOGY TABLE 6.2. CONVENTIONAL AND EMERGING TECHNOLOGY COST ESTIMATES Traditional Paving Systems Typical Cost Basis per Ton Basis per yd2 Asphalt concrete (HMA) at 12 in. thick $64/ton $64/ton $42/yd2 Portland cement concrete at 12 in. thick $130/yd3 $64/ton $43/yd2 HMA overlay, 2 in. thick $64/ton $64/ton $7/yd2 Chip seal — — $2/yd2 Project Cost Miscellaneous Info Basis per yd2 UTCRCP (N1 Freeway, South Africa, completed June 2010). Section contained ∼16,000 m2 of UTCRCP paving. R590/m2 ~$85/m2 ~$70/yd2 TH-62 Minnesota: precast panels 12 ft × 12 ft × 9.25 in. (completed June 2005). Cost/yd2 excludes traffic control, grinding, and striping. Cost/yd2 does include removal of preexisting 8-in. JRCP. Contained 288 yd2 of precast panels. — Test section was small, ∼288 yd2 $575/yd2 Caltrans precast posttensioned test section, constructed in 2004. — Test section was ∼1,000 yd2 $224/yd2 Note: Per yd2 basis based on equal thickness of HMA and PCC. Only the material costs were considered. Assumed densities are 145 lb/ft3 for HMA and 150 lb/ft3 for PCC. TABLE 6.3. EXPECTED PERFORMANCE AND COSTS ASSOCIATED WITH A SELECTION OF PAVEMENT PRESERVATION TREATMENTS Pavement Type Expected Treatment Performance (years) Estimated Unit Cost Existing HMA Surfaced Pavement Crack filling 2–4 $0.10–$1.20/ft Crack sealing 3–8 $0.75–$1.50/ft Slurry seal 3–5 $0.75–$1.00/yd2 Chip seal, single course 3–7 $1.50–$4.00/yd2 Thin HMA overlay (dense graded; 0.875–1.5 in. thick) 5–12 $3.00–$6.00/yd2 Profile milling 2–5 $0.35–$0.75/yd2 Ultrathin whitetopping (2–4 in. thick) NA $15.00–$25.00/yd2 Existing PCC Surfaced Pavement Joint resealing 2–8 $1.00–$2.50/ft Crack sealing 4–7 $0.75–$2.00/ft Diamond grinding 8–15 $1.75–$5.50/yd2 Partial-depth concrete patching 5–15 $75–$150/yd2 (based on patched area) Full-depth concrete patching 5–15 $75 to 150/yd2 (based on patched area) Dowel bar retrofit 10–15 $25.00 to 35.00/bar Thin HMA overlay (0.875–1.5 in. thick) 6–10 $3.00 to 6.00/yd2 Source: After Peshkin et al., 2010.

360 GUIDE TO USING EXISTING PAVEMENT IN PLACE AND ACHIEVING LONG LIFE REFERENCES Ahlrich, R., and G. Anderton. “Construction and Evaluation of Resin Modified Pavement,” Final Report, Technical Report GL-91-13, U.S. Army Corps of Engineers, Vicksburg, Miss., 1991. Battey, R., and E. Whittington. “Construction, Testing and Performance Report on the Resin Modified Pavement Demonstration Project,” Report FHWA/MS-DOT-RD-07-137, Mississippi Department of Transportation, Jackson, 2007. Burnham, T. “Precast Concrete Pavement Panels on Minnesota Trunk Highway 62—First Year Performance Report,” MN/RD 2007-19, Minnesota Department of Transportation, St. Paul, 2007. Ebels, L.-J., and R. Burger. New Concrete Pavement Technology Put to the Test on N1 Freeway. Civil Engineering Magazine, Vol. 18, No. 7, August 2010, p. 50. Federal Highway Administration (FHWA). “Precast Prestressed Concrete Pavement for Reconstruction and Rehabilitation of Existing Pavements,” Concrete Pavement Technology Program, Federal Highway Administration, 2009. Kannemeyer, L., B. Perrie, P. Strauss, and L. du Plessis. “Ultra Thin CRCP: Modeling, Testing Under Accelerated Pavement Testing and Filed Application for Roads.” Presented at 9th International Conference on Concrete Pavements, San Francisco, August 17–21, 2008. Kuo, S., J. Armaghani, and D. Scherling. “Accelerated Pavement Performance Testing of Ultra-Thin Fiber Reinforced Concrete Overlay, Recycled Concrete Aggregate, and Patching Materials,” Proc., First International Conference on Accelerated Pavement Testing, Reno, Nev., 1999. Merritt, D., B. McCullough, N. Burns, and A. Schindler. “The Feasibility of Using Precast Concrete Panels to Expedite Highway Pavement Construction,” Research Report 1517-1, Center for Transportation Research, University of Texas at Austin, 2000. Merritt, D., B. McCullough, and N. Burns. Design-Construction of a Precast, Prestressed Concrete Pavement for Interstate 10, El Monte, California. PCI Journal, Vol. 50, No. 2, March–April 2005. Peshkin, D., K. Smith, A. Wolters, J. Krstulovidh, J. Moulthrop, and C. Alvarado. “ Guidelines for the Preservation of High Traffic Volume Roadways,” Draft Final Guide- lines, Project R26, SHRP 2, Transportation Research Board of the National Academies, Washington, D.C., 2010. Washington State Department of Transportation (WSDOT). “Trends in Highway Mate- rial Costs,” Washington State Department of Transportation, Olympia, October 21, 2010. http://www.wsdot.wa.gov/biz/construction/CostIndex/pdf/constructioncosts.pdf.