Multi-scale study on the whole process adhesion behaviour of steel slag and SBS/CR composite modified asphalt

Clarifying the action mechanism of steel slag and waste tire crumb rubber in asphalt mixtures is of great significance in realising solid waste resourcing and improving road quality. This study focused on the adhesion behaviour of asphalt mixture from mixing to application and explored the adhesion mechanism of steel slag and SBS/crumb rubber composite modified asphalt (SBS/CR CMA) on multiple scales. The results show that the steel slag and SBS/CR CMA exhibit excellent adhesion properties during mixing and application, and the electrostatic force plays a leading role in the whole adhesion process. The contribution of steel slag to adhesion is 3CaO·SiO2 > 2CaO·SiO2. Among them, the strong electrostatic interaction between 3CaO·SiO2 and CR is the main mechanism to improve the adhesion property of steel slag and SBS/CR CMA. 3CaO·SiO2 in steel slag can slow down the flow of water molecules on its surface, and the strong force between CR and 3CaO·SiO2 improves the water damage resistance of steel slag-SBS /CR CMA significantly. Selective adhesion occurs when asphalt is mixed with different aggregates, and the adhesion object depends on the initial adhesion work between asphalt and aggregates.