Abstract Manager

This study aims to enhance the low-temperature performance to create a high-performance asphalt concrete (HPAC) mix for use in a pavement’s base course in cold regions. This is achieved by incorporating polyethylene terephthalate (PET) fibres of different lengths and enriching the asphalt binders (from two different sources) with asphaltenes, a by-product derived from the Alberta oil sands. Binder H is a crude oil binder with a continuous performance grading (PG) of 70.2-25.9, and Binder P is an Alberta oil sands binder with a continuous grade of PG 69.0-26.6. Both binders are modified with an optimum content of 12% asphaltenes by weight of the binder to reach the required dynamic modulus value for HPAC of 14 GPa at 15°C and 10 Hz. Also, an optimum dosage of waste PET fibres of 0.15% by weight of total mixture is used to modify Binder H mixture using three lengths of 6, 12, and 18 mm, and using only the optimum PET dosage and length in Binder P mixture. The cracking resistance, represented in the fracture energy and tensile strength, is tested at low temperatures of -20, -10, and 0°C and assessed using the creep compliance and indirect tensile strength test method. Results show that the optimal fibre length is 12 mm in that highest fracture energy is observed in the sample with 0.15% PET fibres that are 12 mm long. At the lowest test temperature of -20°C, this mix shows a 12.7% increase in the fracture energy compared to the next best-performing sample containing 6mm PET fibres. At -10°C, both samples with 6mm PET and 12mm PET fibres exhibit comparable high fracture energy values of 5,613 and 5,600 J/m², respectively. As for the tensile strength, the highest values of 7.4 and 6.8 MPa are recorded for mixtures containing 12mm PET fibres at the coldest temperatures of -20°C and -10°C, respectively. With regards to the effect of binder source, enhanced cold temperature performance is evident as the two mixtures with both Binder H and P modified with asphaltenes and 0.15% of the 12mm-long fibres exhibit fracture energies surpassing those of the control unmodified mixes at -20°C and -10°C. In particular, at -20°C the modified Binder H mix attains a fracture energy of 5,261 J/m², while the modified Binder P mix slightly trails behind with a value of 5,121 J/m².