Investigation of the bonding properties of bitumen using a novel modified binder bond strength test

The binder bond strength (BBS) test can directly quantify the bonding of bitumen-stone joints. However, the index "bond strength" used in this method cannot provide a clear distinction when evaluating the performance of various bitumen, and some results do not correspond to the field feedback related to the bonding performance. This study introduces a novel modified BBS test using the universal testing machine (UTM). The results of the standard BBS test and the BBS-UTM test on six unmodified bitumens and a styrene-butadiene-styrene modified bitumen (SBSMB) are compared, with the Cantabro loss test to validate the accuracy of the BBS-UTM test. The results show that the "bond energy" can be considered the critical indicator for characterising the bonding performance of different binders. The force-displacement curve in the BBS-UTM test is analysed and provides a mechanistic explanation for the mechanical response of bitumen during pull-off. The four-component test is conducted to link the bitumen composition characteristics to its bonding performance. It is found that bitumen adhesion is correlated to the content of asphaltenes. A higher saturates content shows more contribution of tenacity in the total bond energy, and an excessively high ratio of asphaltenes to resins may result in low bond energy. •A novel test with a new index is proposed to characterise the bonding of bitumen.•The adhesion and tenacity energy of bitumen-stone joints are separated and analysed.•SBS-modified bitumen shows poor adhesion but excellent tenacity energy.•The bonding indices of bitumen are closely related to its component characteristics.