Semi-Mechanistic-Empirical approach to predict the performance of waste polyethylene terephthalate (PET) stone mastic asphalt pavement under static load

The high bitumen content in stone mastic asphalt (SMA), typically between 6 and 7%, has reduced the demand for road paving and the need to use new material to partially replace the binder content is of great significance. However, the utilization of waste polyethylene terephthalate (PET) as a partial replacement of bitumen in SMA has shown good results; therefore, it is imperative to characterize the mix performance under axle load to ensure that performance is not compromised in pursuit of economic and environmental solutions. This article utilizes the KENLAYER algorithm to predict a polished pavement cross section constructed with waste polyethylene terephthalate (PET) stone mastic asphalt (SMA) as the surface layer. The modified mix was investigated, and the dynamic modulus |E*| was fitted via excel spreadsheet due to vehicle speed, loading duration, and contact length. Six (6) parameters were studied, including critical strains at the bottom of the PET-SMA layer and top of the subgrade, vertical stresses, deflections, damage factors, and the pavement design life considering the influence of standard load groups with dual wheels (Tandem & Tridem) and the variations in temperature on the mix modulus values. The effect of axle load rate and changes in the mix dynamic modulus was observed to be very significant. The results revealed that the PET-SMA performed satisfactorily with an acceptable pavement service duration. To conclude, using PET as a partial replacement for bitumen in SMA is one of the promising strategies for reducing the high amount of bitumen content and similarly promotes the sustainability of plastic waste.