Abstract
Fatigue is considered a major pavement structural distress and an important part of a performance-based mix design. Currently, the fatigue model of asphalt mixture, especially the mixture incorporated with fibers, is not perfect. In this paper, the central-point bending fatigue test was conducted by constant strain mode with MTS apparatus. The fatigue performance and model of polyacrylonitrile (PAN) fiber-reinforced asphalt mixture produced with different fiber contents and asphalt contents were reported. The results indicated that the fatigue life of fiber reinforced mixture was higher than the reference one. The effects of fiber contents and asphalt contents on fatigue life were discussed. The mechanism of an optimum fiber content for the fatigue life in the fiber reinforced asphalt mixture was explained. The statistical analysis of variance (ANOVA) method and regression method were used to evaluate the effects of fiber content, strain level, and volumetric parameters, etc. on the fatigue life of an asphalt mixture. This paper presents a new fatigue performance model of a PAN fiber-reinforced asphalt mixture, including the fiber content, tensile strain, mixture initial flexural stiffness, and voids filled with asphalt (VFA). Compared to the earlier fatigue equations, the accuracy of the new fatigue model with the fiber content is improved significantly according to the statistical analysis results. Meanwhile, the model can preferably reveal the effect of fiber content, strain level, initial stiffness, and VFA on fatigue life.
Highlights
The fatigue resistance of an asphalt mixture refers to its ability to withstand repeated bending without fracture
The fatigue test results of the fiber reinforced asphalt mixture with different fiber contents and asphalt contents are shown in Table 5 and Figure 5
The total surface area of aggregates is basically equal for the same gradation aggregates. This means that the thickness of the asphalt film around aggregates increases by nearly 8%, which is beneficial to the fatigue life of the asphalt mixture; On the one hand, the physical and chemical reactions occur on the interface between the asphalt and fiber; on the other hand, the asphalt mortar with a higher viscosity is formed after the addition of fibers
Summary
The fatigue resistance of an asphalt mixture refers to its ability to withstand repeated bending without fracture. Hajj et al [19] conducted tests to evaluate the fatigue characteristics of HMA, designed using the Superpave volumetric method and Nevada’s Hveem method Their tests used the flexural beam fatigue test under the strain-controlled mode of loading. Where, Nf is the fatigue life; εt is the applied tensile strain; S0 is the mixture initial flexural stiffness; and k1 , k2 , and k3 are experimental coefficients. Va + AV where, Nf is the fatigue life; εt is the applied tensile strain; S0 is the mixture initial flexural stiffness; Va is the asphalt content; AV is the air void content; and k1 , k2 , k3 , and k4 are experimental coefficients. Little information is available on the fatigue model of polymer fiber-reinforced asphalt mixtures None of these studies researched the flexural fatigue behavior of the composite. The fatigue property of PAN fiber-reinforced asphalt mixtures is analyzed and a new fatigue equation for PAN fiber-reinforced asphalt mixtures has been generated
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