Study of Ageing on Bitumen–Mineral Adhesive Properties under Iso-Temperature and Iso-Stiffness Conditions

The adhesive properties of bitumen–mineral determine the ravelling and cracking resistance of asphalt pavements. During service, asphalt pavements undergo a variety of ageing effects, which significantly affect the adhesive properties. In this study, a direct tensile pull-off test based on the universal testing machine is applied. The adhesive properties of bitumen at various levels of ageing to limestone are evaluated under iso-temperature and iso-stiffness conditions, respectively. The stripping resistance of these bitumen binders and limestone aggregates in the presence of water is also tested using the rolling bottle test, and the results of the pull-off test and rolling bottle test are compared. The results of the iso-temperature pull-off test show that laboratory short-term ageing and standard long-term ageing improve the adhesive properties of bitumen–mineral and that further long-term ageing has a significant detrimental effect on the adhesive properties. In contrast, the iso-stiffness pull-off test, which eliminates the additional impact of rising stiffness, shows that ageing has a very limited effect on enhancing bitumen adhesion properties. After short-term ageing, the adhesion of bitumen-mineral decreases as bitumen ageing. The rolling bottle test results are consistent with those of the iso-stiffness pull-off test, showing that the additional effect of modulus change due to the hardening of bitumen by ageing needs to be taken into account when investigating the effect of ageing on the adhesive properties of bitumen–mineral.