Understanding the field performance of asphalt binders in continental climates through modulated differential scanning calorimetry

A pavement trial from northern Ontario, Canada is providing insight to inform the use of straight and modified asphalts in continental climate regions. Eight sections were constructed with asphalts which varied in modification type and dose. After 13 years of monitoring, modification is found to significantly influence pavement performance with differences in expected lifespan exceeding 15 years. With increasing interest in modified asphalts, modulated differential scanning calorimetry (MDSC) was performed on the trial binders and their aged residues to shed light on the inherent mechanisms that govern field performance. Paved with recycled engine oil bottom (REOB) tainted asphalt, test section 655-15 has the shortest lifespan. Results showed this section suffered from accelerated aging and had the lowest degree of phase compatibility. Paved with 7% styrene-butane-styrene (SBS) modified asphalt, section 655-13 is expected to last for only 23 years, in contrast to section 655-14, paved with 3.5% SBS modified asphalt, which is expected to last for 36 years. Glass transition results show that SBS modification suppresses the glass transition temperature but high SBS content increases phase incompatibility. A test section paved with straight Cold Lake binder, modified with 0.3 % PET fiber on the mixture, is expected to outperform all others with an expected lifespan of 38 years.