|FHWA > Engineering > Pavements > Concrete > High Performance Concrete Pavements: Project Summary > Chapter 20|
High Performance Concrete Pavements
|PORTLAND CEMENT CONCRETE PROPERTY||EUROPEAN PAVEMENT||MICHIGAN STANDARD PAVEMENT|
|TOP LAYER||BOTTOM LAYER||LCB|
|28-day compressive strength, lbf/in2||5,500||5,000||2,500||3,500|
|28-day flexural strength, lbf/in2||—||—||—||650|
|Maximum w/c (by weight)||0.4||0.42||0.7||0.5|
|Minimum cement content, lb/yd3||752||588||420||550|
|Maximum slump, in.||3||3||3||3|
|Air content, %||6.5 ± 1.5||6.5 ± 1.5||6.5 ± 1.5||6.5 ± 1.5|
|LCB = lean concrete base|
An exposed aggregate surface was specified for the top layer of concrete. This exposed aggregate surface provides surface texture and is expected to reduce noise levels. The exposed aggregate surface was produced through a patented process developed by Robuco, Ltd. of Belgium, consisting of the following steps (Weinfurter, Smiley, and Till 1994):
Joint sawing operations were made through the protective sheeting prior to the brushing operation.
A 406-mm (16-in.) thick, nonfrost-susceptible aggregate subbase was placed directly on the subgrade, and longitudinal edge drains were installed beneath both the inside and outside PCC shoulders (Weinfurter, Smiley, and Till 1994). The outer lane consisted of a 4.1-m (13.5-ft) wide outer slab to reduce critical edge loading encroachments.
Transverse contraction joints were spaced at 4.6-m (15-ft) intervals and were designed to match those joints in the underlying LCB. Polyethylene-coated dowel bars, 32 mm (1.25 in.) in diameter and 508 mm (20 in.) long, were placed on chairs at the mid-depth of the composite slab and at the variable spacings shown in Figure 54 (Weinfurter, Smiley, and Till 1994).
Figure 54. Variable dowel spacings used on European pavement section
(Weinfurter, Smiley, and Till 1994).
The longitudinal and transverse joints were sealed with an ethylene propylene diene terpolymer (EPDM) seal (Weinfurter, Smiley, and Till 1994). Similar to conventional neoprene compression seals, these seals are placed without a lubricant/adhesive and require only a clean (but not dry) joint prior to installation (Weinfurter, Smiley, and Till 1994).
MDOT has been monitoring the performance of both sections since 1993. Performance data collected include surface distress, ride quality, surface friction, and tire noise levels (Weinfurter, Smiley, and Till 1994). Seasonal pavement deflection measurements are also taken periodically to identify any structural inadequacies that may develop in either pavement section (Weinfurter, Smiley, and Till 1994). Although limited performance monitoring continues, no formal reports have been prepared since 2000.
The construction of the European pavement section was accomplished without any major difficulties. Slower production rates were noted, much of which is attributed to an unfamiliarity with two-layer construction and exposed aggregate surfaces (Weinfurter, Smiley, and Till 1994). Among some of the specific recommendations for similar future projects include (Weinfurter, Smiley, and Till 1994):
In the first year after the construction of the pavement sections, distress surveys, skid testing, and noise studies were conducted. Results of those monitoring activities are given below (Smiley 1995):
A 5-year analysis of the performance of the two test sections was just recently completed (Buch, Lyles, and Becker 2000). This analysis included an evaluation of traffic, pavement distress, roughness, surface friction, and deflection data obtained on the sections from 1993 to 1998. An economic analysis of each section was also conducted. Summaries of these analyses are provided in the following sections.
Pavement performance is typically assessed in terms of how well the pavement stands up to traffic loading, which is generally expressed in terms of 80-kN (18-kip) equivalent single-axle load (ESAL) applications. However, because of variable commercial traffic levels and questionable vehicle classification data, the 5-year evaluation used total traffic volume as the basis for performance comparisons (Buch, Lyles, and Becker 2000). The cumulative total traffic volume (traffic in all lanes in one direction) for these sections is shown in Figure 55 (Buch, Lyles, and Becker 2000).
Figure 55. Cumulative total traffic volumes for MI 1 test sections
(Buch, Lyles, and Becker 2000).
Pavement distress surveys are conducted regularly on Michigan's highways as part of MDOT's pavement management activities. The condition of a pavement is reported in terms of a distress index (DI), which is computed based on the type, extent, and severity of distress. Data from 1995 and 1997 showed a DI of 0 for the European pavement section, indicating a distress-free pavement well below the rehabilitation trigger value of 50 (Buch, Lyles, and Becker 2000). The 1995 and 1997 DI values for the Michigan standard pavement section are 1 for both years, also suggestive of a pavement in very good condition (Buch, `Lyles, and Becker 2000).
MDOT has monitored the roughness of these pavement sections using an inertial profiler. International Roughness Index (IRI) values computed from the measured profiles are shown in Figure 56 as a function of total traffic (Buch, Lyles, and Becker 2000). The European pavement is noted to be slightly rougher than the Michigan standard pavement, but overall the smoothness levels have remained fairly constant. It should be noted that IRI values less than 1.3 m/km (80 in./mi) are considered to be smooth (Buch, Lyles, and Becker 2000).
Figure 56. Computed IRI values for MI 1 test sections
(Buch, Lyles, and Becker 2000).
Deflection testing on the test sections has been performed twice: once in November 1993 and once in April 1995 (Buch, Lyles, and Becker 2000). The 1993 measurements were taken during daylight hours prior to the pavement being opened to traffic; the 1995 measurements were taken at night because of lane closure restrictions (Buch, Lyles, and Becker 2000). An FWD using a 4000-kg (9000-lb) load was used to conduct the testing.
Table 26 summarizes the results of the FWD testing. It is observed that the magnitude of the maximum mid-slab deflections are less for the European pavement than for the Michigan standard pavement, which is not surprising given the strong base and thick subbase located beneath the European pavement slab. However, it is surprising that the load transfer efficiencies for both sections are as low as they are for such new pavements, and that the most recent LTEs for the European pavement are less than the Michigan standard pavement. One possible reason for this is the wet weather conditions that had preceded the April 1995 testing, which may have contributed to warping of the slabs (Buch, Lyles, and Becker 2000).
|TEST PROPERTY||TEST LOCATION||EUROPEAN PAVEMENT||MICHIGAN STANDARD PAVEMENT|
|NOVEMBER 1993||APRIL 1995||NOVEMBER 1993||APRIL 1995|
|Average maximum mid-slab deflection||Outside lane||1.30 mils||1.41 mils||1.99 mils||2.05 mils|
|Lane left of outside lane||1.37 mils||1.32 mils||2.13 mils||2.07 mils|
|Inside lane||1.27 mils||1.33 mils||2.28 mils||2.07 mils|
|Average transverse joint load transfer efficiency||Outside lane||77%||59%||68%||70%|
|Lane left of outside lane||79%||62%||72%||70%|
Friction numbers measured for these test sections are shown in Figure 57 (Buch, Lyles, and Becker 2000). The friction numbers for the Michigan standard pavement section are higher than those of the European pavement section, which is somewhat unexpected because of the exposed aggregate surface. Both sections show an initial increase in friction number, which is most likely due to the wearing off of the curing compound (Buch, Lyles, and Becker 2000).
Figure 57. Computed friction numbers for MI 1 test sections
(Buch, Lyles, and Becker 2000).
It was expected that the European pavement section would cost more to construct than the Michigan standard pavement, but the result would be a longer-lasting concrete pavement. A cost analysis showed that the European pavement cost about 234 percent more to construct than the Michigan standard pavement (Buch, Lyles, and Becker 2000). However, it should be noted that the European pavement was a demonstration project that was constructed as part of an "open-house" conference, so the costs are not representative of a conventional paving project.
An economic analysis was conducted to compare the life-cycle costs (LCC) of the European and Michigan standard pavements. This required several assumptions regarding future performance, future maintenance cycles, and future rehabilitation schedules. Based on the analysis, it was determined that the European pavement is not competitive with the Michigan standard pavement. However, the calculations are theoretical in the sense that the projected time to maintenance and rehabilitation activities are based on MDOT estimates (Buch, Lyles, and Becker 2000). In addition, the construction costs of the European pavement may not be representative since it was a demonstration project. Nevertheless, the extrapolated data suggest that in order for the European pavement to be competitive, it can cost no more than approximately 17 percent more than the Michigan standard pavement (Buch, Lyles, and Becker 2000).
Michigan Department of Transportation
8885 Ricks Road
P.O. Box 30049
Lansing, MI 48909
Buch, N., R. Lyles, and L. Becker. 2000. Cost Effectiveness of European Demonstration Project: I-75 Detroit. Report No. RC-1381. Michigan Department of Transportation, Lansing.
Federal Highway Administration (FHWA). 1992. Report on the 1992 U.S. Tour of European Concrete Highways. FHWA-SA-93-012. Federal Highway Administration, Washington, DC.
Larson, R. M., S. Vanikar, and S. Forster. 1993. U.S. Tour of European Concrete Highways (U.S. TECH), Follow-Up Tour of Germany and Austria - Summary Report. FHWA-SA-93-080. Federal Highway Administration, Washington, DC.
Smiley, D. L. 1995. First Year Performance of the European Concrete Pavement on Northbound I-75 - Detroit, Michigan. Research Report R-1338. Michigan Department of Transportation, Lansing.
Weinfurter, J. A., D. L. Smiley, and R. D. Till. 1994. Construction of European Concrete Pavement on Northbound I-75 - Detroit, Michigan. Research Report R-1333. Michigan Department of Transportation, Lansing.
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