Bituminous sealants used in the maintenance of roadways are installed hot and heated to 150–200°C during installation. High temperatures can degrade polymers in sealants, but there is no standard method to account for this possible degradation. In an attempt to find such a method, the aging of two sealants in large kettles during field applications was compared to that obtained in the laboratory by heating in a small kettle. The results indicate that 4 h of small kettle aging at the highest suggested sealant application temperature (HiSAT), or about 2 h at HiSAT + 10°C, provided as much copolymer aging as that found in sealants sampled midway through installation. Keywords: agingasphaltbitumenpolymerdegradationsealants Acknowledgements This work was supported by the Canada–USA Crack Sealant Consortium, also known in the USA as the Federal Highway Administration Pool-Fund TPF5(045). Its members are listed in Collins et al. (2008 Collins, P. 2008. Deformation and tracking of bituminous sealants in summer temperatures: pseudo-field behaviour. International Journal of Pavement Engineering, 9(1): 1–8. [Taylor & Francis Online] , [Google Scholar]).

Bituminous sealants are applied to cracks and joints in pavements, bridges and other civil engineering structures. The sealants are generally applied at 180°C to 200°C, a temperature at which the sealant can degrade. In an effort to better understand the effect of installation on sealant properties, a sealant was collected at regular interval during its installation and analyzed by gel permeation chromatography (GPC), Fourier-transform infrared spectroscopy (FTIR), thermogravimetry (TG), and dynamic shear rheometry (DSR). The analysis of the aged sealants showed that the sealant was in its most degraded state early in the morning due to long pre-installation heating times around 150°C, which caused non-oxidative degradation. The degradation occurred at temperatures below the recommended installation temperatures. The degradation led to sealant stiffening, which was found to arise from a change in polymer structure, and from a loss in bitumen and polymer contents. This loss of organic material led to a relative increase in filler content. It is concluded that sealant preparation conditions, prior to installation, should be better controlled to optimize sealant performance.