Laboratory evaluation of self-healing properties of various modified asphalt

The self-healing capability of asphalt materials has been known for many years. Related studies have focused mostly on the healing mechanism or self-healing behavior during load repetitions. Limited work has been accomplished to fully understand the healing performance of different modified asphalt. In this paper, the effects of various contents of different modifiers on the healing capability of binders were investigated by a simple self-healing test procedure to give suggestions to ensure better choice of asphalt materials with good healing properties. Results from the Binder Bond Strength (BBS) test indicate that the modifier significantly affected the healing potential of asphalt binder depending on both the type and content of modifier that was used. Interestingly, increased modifier content deteriorated the healing capability of the base binder regardless of the type of additive employed, thereby suggesting that soft binders are more desirable for healing. Furthermore, methylene plus methyl hydrogen to carbon (MMHC) ratio was verified to be useful for predicting the healing potential of base asphalt binder but was found to be unsuitable for characterizing the healing potential of modified asphalt. By contrast, rotational viscosity @135 °C can predict the healing property in the case of base and modified asphalt. Finally, the Four-Point Beam Fatigue (4PB) test further confirmed that the BBS test can help to determine the healing potential of asphalt binders in an efficient and simple manner.