Investigating the mechanical properties of asphalt concrete containing waste polyethylene terephthalate

Reviewing the literature shows that limited work has been conducted on polyethylene terephthalate (PET)-modified asphaltic materials with inconsistent results, missing the investigation of some aspects such as the effect of PET particle size. This paper investigated the effects of waste PET content and particle-size distribution on some engineering properties of asphalt concrete. To this end, Marshall specimens of the mixtures containing different ground waste PET contents of 0%, 2%, 4%, 6%, 8%, and 10% (by the weight of asphalt binder) were subjected to Marshall, indirect tensile strength (ITS), moisture damage, and dynamic creep tests. Two different sizes of PET particles were used: one with particles in the range of 1.18-2.36 mm as coarse-graded PET, and the other with particles in the range of 0.297-0.595 mm, as fine-graded PET. ITS test was conducted on dry and conditioned specimens to evaluate moisture damage susceptibility. Dynamic creep tests were performed under the stress level of 300 kPa at 40 degrees C. Results show that, for both coarse- and fine-graded PET particles, the highest Marshall quotient is achieved at 4% of PET content, after which it decreases with increasing the PET content. Furthermore, results indicate that, for both fine and coarse PET particles, the mixture containing 2% of PET content has the highest ITS and resistance against moisture damage. Based on dynamic creep test results, the resistance against permanent deformation decreases with increasing the PET content. Comparing the results for the mixtures containing coarse and fine PET particles shows that a better performance can be achieved using finer PET particles.