High Performance Concrete Pavements Project Summary
Chapter 17. KANSAS 1 (Highway K-96, Haven)
In 1997, the Kansas Department of Transportation (KDOT) constructed an experimental project under the TE-30 program. This project incorporates a wide variety of experimental features, from alternative dowel bars to alternative sawing practices to different mix designs (Wojakowski 1998). The project is located on Highway K-96 near Haven, which is located between Wichita and Hutchinson (see Figure 43).
Figure 43. Location of KS 1 project.
Looking for ways to improve PCC pavement performance, KDOT implemented this project to specifically assess the effects of different design features, mix designs, and construction practices on the constructibility and performance of PCC pavements. Benefits expected to be derived from the project include assessments of the following (Wojakowski 1998):
- Feasibility of including recycled waste materials in a two-lift PCC pavement.
- Feasibility of using a harder aggregate of unknown reactivity mitigated with an appropriate pozzolan in a two-lift PCC pavement.
- Performance of new load transfer devices.
- Life extensions associated with premium materials and concrete mixes.
- Cost-benefit data associated with the various designs.
Project Design and Layout
Two phases were defined in the work plan for this project. Phase I included evaluating the many different construction materials and mix designs to be used in the study, preparing the plans and specifications, doing a construction evaluation, and evaluating and monitoring the project (Wojakowski 1998). Phase II consisted of the actual construction of the test sections.
Constructed in the early fall of 1997, the test sections are located only in the two eastbound lanes of the four-lane divided highway (Wojakowski 1998). Most test sections are 1-km (0.6-mi) long. The soils in the area are typically silty and sandy loams, and the 20-year projected traffic volume is 8,000 vehicles per day, which includes 11 percent trucks (Wojakowski 1998).
The nominal pavement structural design for the test sections is a 254-mm (10-in.) JPCP over a cement-treated base (CTB). Transverse joints are spaced at 4.6-m (15-ft) intervals (except for one section), contain 32-mm (1.25-in.) diameter epoxy-coated steel dowels (except for two sections), and are sealed with neoprene compression seals (except for part of one section) (Wojakowski 1998). Longitudinal joints contain tie bars at 914-mm (36-in.) spacings and are sealed with a hot-poured, low-modulus sealant (Wojakowski 1998).
Thirteen experimental pavement sections were constructed on this project, incorporating a wide range of design and construction variables. A description of the features of each experimental section is provided below (Wojakowski 1998):
- Section 1 - Control section. This pavement section reflects the nominal pavement structural design, containing 32-mm (1.25-in.) diameter dowel bars and placed in a single lift. The concrete mixture contains 337 kg/m3 (564 lb/yd3) of Type II cement, a water-cement ratio (w/c) of 0.47, and 6.5 percent air. Three aggregates - 35 percent of a coarse limestone (19 mm [0.75 in.] top size), 15 percent of a pea gravel, and 50 percent of a coarse sand - were used and blended to produce a grading approximating a "Shilstone" haystack gradation curve. Consolidation of the concrete was specified to be 98 percent of the vibrated unit weight when measured by a nuclear density meter.
- Section 2 - Single saw cut. The first 31 transverse joints of this section were created using a narrow (6 mm [0.25 in.]) single saw cut and left unsealed, whereas the remaining 79 joints were widened and sealed with a hot-poured material. Other than the transverse joint sealant, other aspects of this pavement are the same as the nominal pavement structural design.
- Section 3 - Nontraditional dowel type. With the same nominal structural design as the control, this section incorporates 51-mm (2-in.) diameter FiberCon™ fiberglass dowels, manufactured by Concrete Systems, Inc. These dowels are a composite fiberglass tube filled with a high-strength cement grout. One-half of the length of the bar is machined to a smooth surface of 48 mm (1.9 in.) diameter to allow slippage of the bar as the joint opens and closes. The bars are placed on center-to-center spacings of 305 mm (12 in.).
- Section 4 - X-Flex™ load transfer device. This short section, consisting only of five joints, incorporates a unique load transfer device called the X-Flex™, developed at Kansas State University. As shown in Figure 44, the configuration of the X-Flex™ is such that the "X" part of the device goes across the transverse joint with the far ends curving to make a loop in a continuous design; wheel loads are transferred through tension in the "X" part of the device rather than by shear. The device is made from 13 mm (0.5 in.) epoxy-coated steel cast bars and spaced at 305-mm (12-in.) centers across the joint. Other design aspects of this section are the same as the nominal pavement design.
- Section 4a, 5, and 6 - Alternate saws. Three sections were constructed that used different lightweight saws for the establishment of the transverse joints. Section 4a used a Soff-Cut™ saw (to depths of 38 and 64 mm [1.5 and 2.5 in.]), section 5 used a Target saw (to depths of 25, 44, and 64 mm [1, 1.75, and 2.5 in.]), and section 6 used a Magnum saw (to depths of 25, 44, and 64 mm [1, 1.75, and 2.5 in.]). The rest of the design features of this section are the same as the nominal structural design.
- Section 6a - Polyolefin fiber PCC. This short (152-m [500-ft]) section incorporates polyolefin fibers in the PCC mix design. The transverse joint spacing was extended to 18.3 m (60 ft), and the longitudinal lane-lane joint was eliminated. The fibers are 1.57 mm (0.062 in.) in diameter and were added at the rate of 15 kg/m3 (25 lb/yd3). The w/c of the mix was increased from 0.45 to 0.49 to provide additional workability.
- Section 7 - Longitudinal tining. Instead of conventional transverse tining, this section incorporates longitudinal tining impressed on the surface of the fresh concrete surface. The primary purpose of longitudinal tining is to reduce noise levels produced by passing vehicles. All other design aspects of this section are the same as the nominal structural pavement design.
- Section 8 - Special curing compound. A special high solids curing compound, conforming to ASTM C 1315, was applied to this section. The purpose is to compare the effectiveness of the special curing compound to the conventional curing compound in terms of surface integrity and compressive strength. The curing compound was applied at the rate of 0.036 L/m2 (0.03 gal/yd2), which is about half the rate recommended for a rough surface. All other design elements for this section are the same as the nominal pavement design.
- Section 9 - Two-lift construction with recycled asphalt pavement (RAP). This section used a two-lift construction process in which the bottom 178 mm (7 in.) of pavement used 15 percent recycled asphalt pavement in place of the intermediate-sized well gravel. Laboratory testing indicated that this mixture could produce 28-day strengths of 27.6 MPa (4,000 lbf/in2). The top lift was placed 76-mm (3-in.) thick using the standard PCC mixture. All other design aspects for this section are the same as the nominal pavement design.
- Section 10 - Lower w/c concrete. This section employed a high-range water reducer to lower the w/c of the mixture by 0.05 from the standard w/c of 0.47. The rest of the pavement design is the same as the nominal structural pavement design.
- Section 11 - Two-lift construction with igneous rock. This section used a two-lift construction process in which the top 76 mm (3 in.) incorporates rhyolite, a hard igneous rock. The objective of this design is to evaluate the resistance of the pavement to polishing, to which the limestone aggregates commonly used by KDOT are susceptible. Because the rhyolite is potentially susceptible to alkali-silica reactivity (ASR), a calcined natural clay pozzolan called DuraPoz™ was used to replace 20 percent of the cement (by weight) in the 76-mm (3-in.) surface layer. The bottom 178 mm (7 in.) of this pavement used a soft, high-absorption durable limestone. A 25-mm (1-in.) maximum size that passed the State's freeze-thaw durability test (ASTM C 666, Procedure B) was used.
- Section 12 - Two-lift construction with lower w/c concrete. This two-lift construction section used the same lower w/c PCC mixture used in section 10 but only in the top 76 mm (3 in.) layer. The bottom 178 mm (7 in.) layer used the same 25-mm (1-in.) soft high absorptive limestone used in section 11. The remaining design aspects of this section are the same as the nominal pavement design.
- Section 13 - Random transverse tining and special curing compound. This section was constructed in the spring of 1998 and used a special tining rake that imparted variably spaced transverse impressions on the surface of the fresh concrete to reduce tire-surface noise. Additionally, the remainder of the high-solids special curing compound used on section 8 was applied at the rate of 0.18 L/m2 (0.04 gal/yd2). All other design elements of the section are the same as the nominal pavement design.
Figure 44. Photo of X-Flex™ load transfer devices.
Table 17 provides the simplified experimental design matrix for the sections included in this project. The layout of the pavement test sections is illustrated in Figure 45.
|CONVENTIONAL PCC MIX WITH SINGLE-LIFT CONSTRUCTION||TWO-LIFT CONSTRUCTION (RECYCLED ASPHALT ON BOTTOM)||TWO-LIFT CONSTRUCTION (IGNEOUS ROCK ON TOP)||TWO-LIFT CONSTRUCTION (LOW W/C ON TOP)||PCC MIX WITH POLYOLEFIN FIBERS|
|Conventional Sawcutting Equipment||Lightweight Sawcutting Equipment||Conventional Sawcutting Equipment||Conventional Sawcutting Equipment||Conventional Sawcutting Equipment|
|Steel Dowels||FiberCon Dowels||X-Flex Device||Steel Dowels||Steel Dowels||Steel Dowels||Steel Dowels|
|Compression Seals||Compression Seals||Hot-Pour Sealant||No Sealant||Compression Seals||Compression Seals|
|Conventional w/c||Conventional Curing Compound||Conventional Transverse Tining||Section 1||Section 3||Section 4||Section 4a Section 5 Section 6||Section 2||Section 2 (31 jts)||Section 9||Section 11||Section 12||Section 6a|
|Longitudinal Tining||Section 7|
|Random Transverse Tining|
|High Solids Curing Compound||Conventional Transverse Tining||Section 8|
|Random Transverse Tining||Section 13|
|Lower w/c||Conventional Curing Compound||Conventional Transverse Tining||Section 10|
Figure 45. Layout of KS 1 project (Wojakowski 1998).
State Monitoring Activities
During the construction of the test sections, several incidents of note were observed by the researchers. These are summarized below (Wojakowski 1998):
- Section 4. Because they were placed only about 38 mm (1.5 in.) below the surface, several of the X-Flex™ load transfer devices were struck and dislodged by the paver during construction. Consequently, some of these devices had to be replaced by dowels and the transverse joint hand finished.
- Section 5. Sawing with the Soff-Cut™ lightweight saw began about 3 hours and 20 minutes after the concrete was placed. For the 40 joints cut to a depth of 38 mm (1 in.), 6 cracks occurred beneath the saw cut after 1 day, 18 cracks occurred beneath the saw cut after 2 days, 23 cracks after 3 days, 31 cracks after 4 days, 35 cracks after 5 days, and 39 cracks after 7 days. No cracks were observed within the panels for this section or for any of the sections that employed the lightweight saws.
- Section 6. Intermediate cracks occurred almost immediately after this fiber-reinforced PCC pavement was placed. During the first night, intermediate cracks formed on 5 of the 8 panels that were paved, and by the 5th day after placement, 10 cracks had appeared in the 8 panels. The panels containing two cracks were noted to be the first two placed on the day that had a high temperature of 35 °C (95 °F) and a low of 21 °C (69 °F).
- Section 8. The special curing compound was applied with the expectation that improved curing would lead to a more durable pavement. Unfortunately, the environmental conditions at the time of application were quite mild, and the actual coverage rate (0.035 L/m2 [0.03 gal/yd2]) was one-half the recommended value.
- Section 9. Limited funding prevented the use of a separate paver for the lower lift. Therefore, a belt placer/spreader was used for the placement of the lower lift, the mix design of which had to be stiffened to accommodate its placement. An interval of about 30 minutes was needed between the placement of the two lifts. Small depressions were noted when the top lift was dropped on the bottom lift and some intermixing of the two lifts occurred, but for the most part the process was workable and adequately controlled. This same construction procedure was essentially followed for all two-lift sections.
- Section 10. In spite of the lower w/c used in the mix design for this section, it was found to be workable and easy to finish. This workability is attributed to the lubrication provided by the high-range water reducer used to reduce the w/c.
- Section 13. The weather at the time that this section was constructed in 1998 mandated the use of cold-weather concreting procedures. The special curing compound was applied at the specified rate of 0.18 L/m2 (0.04 gal/yd2).
Early Mix Property Data
During the construction of the different sections, several key mix design properties were measured. These measurements are summarized in Table 18. Generally speaking, most of the results appear reasonable for the various mix designs.
KDOT has been monitoring the performance of these test sections since 1998. The following information is collected: distress data (cracking, faulting, spalling), joint load transfer efficiency, noise, and surface friction (Wojakowski 1998).
Some preliminary results are available from KDOT regarding the costs and performance of these sections. These results are described in the following sections.
Construction costs for these sections are summarized in Table 19 and illustrated in Figure 46. Some notes regarding these costs are documented by Wojakowski (1998):
- Section 1. This figure includes the costs of both the mainline pavement and the shoulders.
- Section 3. For the small quantities of this project, the costs of the FiberCon™ dowels were $28.87/m ($8.80/ft) as compared to $8.00/m ($2.44/ft) for conventional epoxy-coated steel dowels. With a larger project and volume pricing, the cost of these dowels could be expected to be around $16.40/m ($5.00/ft).
- Sections 4a, 5, and 6. The lightweight saws provided minimal savings to the overall construction costs.
- Sections 9, 11, and 12. These sections included a two-lift construction process that added considerable cost. The two-lift construction costs included a second batch plant, extra hauling of material, a concrete belt placer/spreader, and extra labor for hauling.
|SECTION||AVERAGE SLUMP, IN.||AVERAGE AIR CONTENT, %||AVERAGE UNIT WEIGHT, LB/FT3||AVERAGE FLEXURAL STRENGTH, LBF/IN2||CORE COMPRESSIVE STRENGTH, LBF/IN2 (28-DAY)|
|1—Control||0.6||6||142||525 (7 days)||4,583|
|4a—Lightweight Soff-cut saw||N/A||N/A||N/A||N/A||4,530|
|5—Lightweight Target saw||1||7||141||N/A||N/A|
|6—Lightweight Magnum saw||N/A||N/A||N/A||N/A||N/A|
|6a—Polyolefin fibers||0||5.2||141||539 (7 days)||4,598|
|8—Special curing compound||2.1||7.4||140||N/A||4,760|
|9—Two-lift with RAP||0.8 (top lift)||6.8||142||N/A||3,843|
|0.8 (bottom lift)||5.8||142.2||517 (5 days)|
|10—Lower w/c||1.1||5.8||144.7||550 (4 days)||5,040|
|11—Two-lift with igneous rock||2.0 (top lift)||4.3||142.2||583 (8 days)||4,780|
|0.8 (bottom lift)||5.9||139.43||475 (4 days)|
|12—Two-lift with lower w/c||1.0 (top lift)||5.8||143.8||583 (6 days)||N/A|
|1.2 (bottom lift)||5.3||137.82||583 (6 days)|
N/A = not available
Flexural strengths measured under third-point loading.
|SECTION||EXPERIMENTAL FEATURE||COST DIFFERENCE FROM CONTROL, $/YD2||TOTAL UNIT COST, $/YD2|
|4a||Soff-Cut lightweight saw||0||25.8|
|5||Target lightweight saw||0||25.8|
|6||Magnum lightweight saw||0||25.8|
|8||Special curing compound||+0.83||26.63|
|9||Two-lift construction with recycled asphalt pavement||+25.12||50.92|
|11||Two-lift construction with igneous rock||+26.05||51.85|
|12||Two-lift construction with lower w/c||+25.09||50.89|
|13||Random transverse tining||0||25.8|
N/A = Not available (experimental device not commercially available)
Figure 46. Relative construction costs by section for KS 1.
Early Performance Data
KDOT is monitoring the performance of these test sections, and has produced two annual reports documenting their early performance (KDOT 1998; KDOT 1999). Visual distress surveys are conducted in which cracking, joint faulting, and joint spalling are recorded. The results from these surveys are illustrated in Table 20. An examination of this table shows that although a few cracks have occurred in a few of the sections, overall these sections are in good condition. Faulting levels are all less than 1 mm (0.04 in.), far below critical faulting thresholds of 2.5 to 3.0 mm (0.10 to 0.12 in.). Joint spalling is observed only on two sections.
The initial profile index values for the test sections are shown in Table 20 and plotted in Figure 47. These values are based on a zero-blanking band. Followup roughness measurements are not available.
|SECTION||EXPERIMENTAL FEATURE||1998 INITIAL PROFILE INDEX, MM/KM||AVERAGE JOINT FAULTING, MM||AVERAGE SPALLING, MM/JOINT||OTHER NOTED DISTRESSES|
|2||Unsealed joints||0||0.21||1 corner crack|
|Sealed joints||0.07||0.1||2 corner cracks|
|3||FiberCon™ dowels||268||0.08||0.25||1.0-m transverse crack|
8 corner cracks
|4a||Soff-Cut lightweight saw||0||0.07|
|5||Target lightweight saw||0||0.07|
|6||Magnum lightweight saw|
|6a||Polyolefin fibers||0.06||0.16||16 mid-panel cracks*; 1 longitudinal crack|
|8||Special curing compound||129||0.02||0||10.6||16.9|
|9||Two-lift construction with recycled asphalt pavement||178||0.05||0.13|
|11||Two-lift construction with igneous rock||166||0.02||0.02|
|12||Two-lift construction with lower w/c||186||0.13||0.17||3.7-m trans. crack|
|13||Random transverse tining||319||0.03|
* These cracks in section 6a were retrofitted with dowel bars in 1999.
Figure 47. Comparison of Initial Profile Index of KS 1 test sections (Zero-Blanking Band).
A noise study was conducted by KDOT in October 1998 to assess the effect of the various tining methods (sections 1, 7, and 13) (KDOT 1998; KDOT 1999). Noise sampling was recorded from a passenger car and a medium-duty dump truck at three locations adjacent to the roadway. The study concluded that there were no significant differences in either the exterior or interior noise levels generated by vehicles traveling over these test sections (KDOT 1998; KDOT 1999).
The interim performance of these test sections is documented in the 2002 Annual Report (KDOT 2002) and the 2003 Annual Report (KDOT 2003) and summarized in Tables 21 and 22. FWD testing was performed in January 2002 and again in January 2004, and the results are shown in Figure 48. Based upon the FWD results, some of the load transfer devices are exhibiting marginal efficiency, particularly for a pavement less than 5 years old.
|SECTION||EXPERIMENTAL FEATURE||AVERAGE JOINT FAULTING, MM|
|AVERAGE SPALLING MM/JOINT|
|OTHER NOTED DISTRESSES|
|2||Unsealed joints||0.02||27.9||1 corner crack|
|Sealed joints||0.07||38.9||6 corner cracks|
|3||FiberCon™ dowels||0.16||32.2||7 corner cracks; 1 1.2-m longitudinal crack|
|4a||Soff-Cut lightweight saw||0.02||143.1|
|5||Target lightweight saw||0.07||10.9|
|6||Magnum lightweight saw||0||50.8|
|6a||Polyolefin fibers||0.23||53.3||3 new longitudinal cracks|
|8||Special curing compound||0.07||27.9|
|9||Two-lift construction with recycled asphalt pavement||0.05||17.8||16 transverse cracks averaging 1.3m each|
|11||Two-lift construction with igneous rock||0.07||27.1||395 transverse cracks averaging 0.4m each; 16 longitudinal cracks averaging 0.4mm each|
|12||Two-lift construction with lower w/c||0.12||12.7||5 longitudinal cracks from 4.6 to 9.14m each; 1 3.7m transverse crack|
|13||Random transverse tining||0.05||22.9||2 corner cracks; 1 0.3m longitudinal crack|
|SECTION||EXPERIMENTAL FEATURE||2003 AVERAGE JOINT FAULTING, MM||2003 AVERAGE SPALLING MM/JOINT||OTHER NOTED DISTRESSES|
|2||Unsealed joints||0.08||59||1 corner crack|
|Sealed joints||0.07||50||6 corner cracks|
|3||FiberCon™ dowels||0.22||38.1||10 corner cracks; 1 1.2-m longitudinal crack|
|4a||Soff-Cut lightweight saw||0.07||85.4|
|5||Target lightweight saw||0.04||21.8|
|6||Magnum lightweight saw||0||44.5|
|8||Special curing compound||0.02||42.3|
|9||Two-lift construction with RAP||0||11||16 transverse cracks averaging 1.3m each; light map cracking on 21 of 30 panels|
|11||Two-lift construction with igneous rock||0||21.2||17 longitudinal cracks averaging 2.6m each; many smaller cracks not recorded|
|12||Two-lift construction with lower w/c||0.08||24.6||5 longitudinal cracks from 4.6 to 9.14m each; 1 3.7-m transverse crack; 1 0.3-m transverse crack|
|13||Random transverse tining||0.07||27.9||2 corner cracks; 1 3.6-m longitudinal crack|
Figure 48. Joint load transfer efficiency on KS 1.
Kansas Department of Transportation (KDOT). 1998. High Performance Concrete Pavement, K-96 Reno County. 1998 Annual Report. Kansas Department of Transportation, Topeka.
---. 1999. High Performance Concrete Pavement, K-96 Reno County. 1999 Annual Report. Kansas Department of Transportation, Topeka.
---. 2002. High Performance Concrete Pavement, K-96 Reno County. 2002 Annual Report. Kansas Department of Transportation, Topeka.
---. 2003. High Performance Concrete Pavement, K-96 Reno County. 2003 Annual Report. Kansas Department of Transportation, Topeka.
Wojakowski, J. B. 1998. High Performance Concrete Pavement. Report No. FHWA-KS-98/2. Kansas Department of Transportation, Topeka.