Effects of inorganic and polymer filler on tertiary damage development in asphalt mixtures
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Two methods, a three-parameter (work-hardening) model and a pseudostrain energy model, were used to characterize permanent deformation-related damage potential of asphalt mixtures. The three parameters were calculated by fitting a curve that describes permanent strain accumulation during repeated load compressive testing. The pseudostrain energy was calculated using the linear viscoelastic constitutive equation. Both methods are appropriate and predict permanent deformation and tertiary damage in asphalt mixtures due to plastic deformation and microcrack development. The effects of a waste carpet coproduct and hydrated lime on permanent deformation were evaluated using the two techniques. The coproduct reduced damage potential in both a dense-graded mix and in a mix designed to exhibit early tertiary damage (tender mix). The coproduct was effective with two compositionally different bitumen within each mixture. Hydrated lime was effective in reducing tertiary damage potential in the dense-graded mixture, but its effectiveness was mixture and bitumen dependent.