Synthesis of design and construction practices
Figure 4. Surface Pavement Deflections of Various Structures
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| Figure 4. Surface Pavement Deflections of Various Structures
Base Layer Max. Deflection mm (mils) Percent Reduction % Granular 0.488 (19.2) 0 Soil cement 0.264 (10.4) 45
CTB 0.240 (9.45) 51 Lean mix 0.214 (8.43) 56
RCC 0.193 (7.61) 60 PCC
0.188 (7.42) 61
Horizontal Stresses and Strains
A pavement structure, when subjected to a load, presents stress and strain responses that are a function of the load magnitude, load location, pressure, and material properties, among other factors. Horizontal stresses have been investigated in the past to understand their effect on failure of HMA and cement-bound materials (e.g., soil cement, CTB, lean mix, RCC, PCC) (Kennedy, 1983; Balbo, 1993). In addition, horizontal strains have also been investigated to predict HMA and cement-bound material fatigue (Kennedy, 1983; Thogersen et al., 2004; Shook et al., 1982).
The results of the horizontal stress analysis are shown in Figure 5. Two observations from the horizontal stresses output of the mechanistic model can be discussed. First, considerably higher compressive and tensile stresses can be observed in the HMA layer of the typical flexible pavement structure (granular base scenario). In the case of rigid bases, the
22 magnitude of both compressive and tensile stresses is significantly reduced. For a flexible pavement structure, the highest compressive stress is located at the top of the HMA layer, whereas the highest tensile stress is located at the bottom of the HMA layer. For the case of composite pavements, the stresses at the top and bottom of the HMA are compressive.
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