Interfacial Adhesion Mechanism of Cement Grout Asphalt Composite Material

It is essential for the adhesion mechanism of the cement-asphalt interface to evaluate the performance of cement-asphalt composite material in a micro-scale. The interface molding experiment was designed in laboratory according to the actual formation process. The influences of environmental temperature, grouting type and asphalt type on the cement–asphalt interfacial bonding characteristics were investigated. The microstructures and features of the cement-asphalt interfacial transition zone were analyzed by scanning electronic microscopy, energy dispersive spectroscopy, and Fourier transformed infrared spectroscopy. The hydrophilia of grouting and asphalt was evaluated by contact angle analysis. The adhesion mechanism of the cement–asphalt interface was investigated. The results show that the bonding strength of the cement–asphalt interface decreases with increasing the temperature. The interfacial bonding strength of sulphoaluminate cement–asphalt is 1.03–1.98 N/mm² at 25–35℃, which is more than 10% greater than that of the Portland cement–asphalt. The interfacial bonding strength of sulphoaluminate cement-asphalt is 0.32–0.38 N/mm² at 60 ℃, which is increased by >80%, compared with that of Portland cement–asphalt. Grouting has a slight emulsification effect on the asphalt interface region, reflecting that the more free asphalt changes to structural asphalt and increases the bond strength. The cement-asphalt interfacial adhesion is due to the physical force. The adhesion failure is the damage between the structural asphalt and free asphalts. Based on the adhesion mechanism, the asphalt-cement composite material can be improved to reduce the crack risk of cement grouting asphalt composite pavement.