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The Effect of Polyethylene Terephthalate Particle Size and Concentration on the Properties of Asphalt and Bitumen as An Additive

Research is extremely limited on the combination of polymeric materials, such as discarded polyethylene terephthalate (PET), with asphaltic materials indigenous to Trinidad and Tobago. This paper examines the effect of both concentration and particle size of added PET on the rheological properties of Trinidad Lake Asphalt (TLA) and Trinidad Petroleum Bitumen (TPB). The PET particle size ranges under study were >0.30 mm to 0.60 mm, >0.60 mm to 0.85 mm, and >0.85 mm to 1.18 mm. These particle sizes were added in concentrations by weight ranging from 2% to 8% PET for TPB and 2% to 4% PET for TLA. Incorporating the waste polymeric material PET in TLA and TPB influenced the physical properties of the resulting blends. For TLA-PET blends, the largest particle size range produced values of complex shear moduli that were higher than pure TLA. The smallest particle size range had the opposite effect. The optimal concentration for fatigue cracking and rutting resistance occurred at 2% PET with the largest particle size range. For TPB-PET blends, the peak value of complex shear modulus generally occurred at concentrations above pure TPB for all particle size ranges and temperatures tested. As the particle size range increased, these peak values occurred at lower concentrations of PET. The 2% concentration for the largest particle size range provided the best fatigue cracking resistance, whereas the particle size range >0.60 mm to 0.85 mm produced the best rutting resistance. This study demonstrated that incorporating waste PET as an additive in road paving mixtures could improve the overall quality of roads and also be a sustainable waste disposal option. Further research is recommended on the effect of PET particle size range and concentrations on TLA/TPB combinations commonly used in road paving applications along with accelerated weathering studies.