Investigating the Creep Properties of PET-Modified Asphalt Concrete

This study has investigated the creep properties of asphaltic concrete modified with different dosages of waste polyethylene terephthalate (PET) in two different ranges of size. Uniaxial dynamic creep test at 40°C was conducted on the cylindrical specimens of the mixtures. The load was applied in two different frequencies of 0.5 and 5Hz. Creep test results showed that the accumulated strain under dynamic loading increased with increasing PET content, with lower values for the mixtures containing finer PET particles. Moreover, it was found that the accumulated strain under the loading with higher frequency was more than that under lower frequency, with higher sensitivity to frequency for the mixtures containing finer PET. The results of dynamic creep tests were used for determination of the constants of a three stage model. The linear creep slope in the second region of the creep curve and the flow number showed that the increase of PET content and size results in decrease of permanent deformation resistance. However, the mixtures modified with 4% of fine and coarse PET particles had the highest loading cycles at the end of primary creep region, where most of the strain was recoverable.