Significant Findings from Full-Scale Accelerated Pavement Testing (2004) / Chapter Skim
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19 CHAPTER THREE VEHICLE–PAVEMENT–ENVIRONMENT INTERACTION INTRODUCTION The topic of vehicle–pavement–environment interaction is complex and probably one of the most controversial aspects of APT. Croney and Croney (1991)
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20 Chapter four discusses the relationship between APT and materials and tests comprehensively. TRAFFICKING APT programs have used both conventional trucks and a variety of vehicles for simulating conventional trafficking of pavements.
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21 undertook studies that would serve as "cross-tests" for the tests that were conducted at the LCPC track in France. The purpose of the cross-tests was to promote international cooperation toward more effective use of large and expensive facilities.
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22 Interaction between Vehicles and Infrastructure Experiment) project (OECD 1998)
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23 of relative performance. In one case (50 mm of asphalt on a 160-mm granular base)
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24 and tire type are the dominant factors affecting the 3-D vehicle–pavement contact stresses. He concluded that high tire edge vertical contact stresses are the principal factors responsible for surface rutting and cracking.
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25 over the surface of the VRSPTA by moving the tire during testing toward one side of the VRSPTA at an angle of 7.5 to 8 degrees. The test results indicated that the transverse stress increases by approximately 30 kPa/degree for conventional Type IV tires and approximately 50 kPa/degree for the wide-based tires.
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26 FIGURE 3 Effect of speed on pavement deflection (Lourens 1995)
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27 Environmental Impact Factors Both non-traffic and traffic-related findings will be discussed in this section. Aging of asphaltic materials, caused by time-related exposure to heat, oxygen, radiation, and wind, is one of the primary non-traffic-related effects that have to be considered.
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28 FIGURE 4 Effects of wheel load and temperature on permanent deformation. softening point temperature of the binder.
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29 occurs in the upper 100 mm of pavements. The speed of loading during the rutting tests averaged 7.6 km/h, while the nominal surface temperature was 55°C.
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30 A model for the IRI was also developed to reflect the permanent deformation at the surface. A number of conclusions were drawn from the study.
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31 FIGURE 6 Comparison of the pavement deformation induced in various crushed-stone base pavements by HVS trafficking (using n = 3) (Walker 1985)
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32 Surface and Subsurface Water In an APT study on the performance of subgrade and base course layers of marginal quality, Vuong et al.
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33 FIGURE 8 Comparison of average layer moduli in site C and cumulative rainfall over time (Vuong et al.
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34 FIGURE 10 Impact of water ingress on pavement performance (Rust et al.
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35 with water on the surface (Walubita et al.
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36 table. Changes in the moduli during the year were monitored and used for the design system.
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