Evaluation on tensile and shear failure characteristics and mechanisms of cement-asphalt interface in semi-flexible paving materials (SFPM) using innovative interface measurement approaches

Abstract

The interaction between the inorganic components of cement phase and the organic components of asphalt phase tends to form a weak interface in the SFPM. However, characteristics of cement-asphalt interface in the SFPM remain unclear owing to a lack of direct and effective measurement methods for the interface. Hence, an interfacial tensile measurement approach and a 45° interfacial shear measurement approach are developed to investigate tensile and shear properties and failure mechanisms of this interface in the SFPM, considering various asphalt binders and interface modifiers. Results show that: the modification effects of interface modifiers are particularly pronounced at temperatures below 0 °C. The application of various interface modifiers results in enhancements of 20–30 % in tensile resistance and 6–8 % in shear resistance at the interface. Among these modifiers, cationic emulsified asphalt demonstrates the most substantial effect. As the temperature increases, the modification effects on the asphalt binder become more pronounced. Notably, the interface modified with high-viscosity modified asphalt binder exhibits the most significant improvements, with tensile resistance increasing by over 50 % and average shear strength rising by 38 %. Additionally, an examination of interface failure mechanisms reveals that, under low-temperature conditions, failure predominantly occurs at the cement phase, whereas at higher temperatures, cohesive failure of the asphalt phase becomes the primary failure mode.