Ageing of Crumb Rubber Modified Bituminous Binders under Real Service Conditions

Abstract

Due to their environmental advantages, crumb rubber modified asphalt binders constitute an interesting alternative to conventional binders for road surfaces of a more durable and sustainable nature. However, in practice, they remain less commonly used than conventional polymer modified binders. This research aims to study the real ageing of crumb rubber modified asphalt binders during their service lives when exposed to various factors, including temperature gradients, the presence of water and oxidation. To this end, research was conducted on a selection of highways built with these binders and located in regions with severe climatic and traffic conditions. The binders from cores of highway surface layers were recovered and tested using the DSR (Dynamic Shear Rheometer) to determine the evolution of the rheological parameters. Crumb rubber modified asphalt binders were studied in comparison with traditional polymer modified bitumen. The analysis of the complex modulus and phase angle was conducted based on frequency and temperature sweep tests, while the evolution of the elastic recovery, Jnr, L-Index and T-Index were assessed from the multiple stress creep and recovery test. The results obtained indicate that crumb rubber modified binders show similar ageing and rheological parameters to those of conventional polymer modified bitumen, even under severe traffic and climate conditions. Furthermore, it was observed that, at high temperatures, the effect caused by real service life ageing was different to that obtained in the laboratory through the RTFO and PAV tests.