Effect of Interfacial Water on the Fatigue Performance of Composite Asphalt Mixture Beams

This study investigated the effect of interfacial water on the performance of asphalt pavement. Composite asphalt beams were used to carry out the four-point bending fatigue test and the direct shear test. Road construction was simulated, and the effects of interlayer water sprinkle amount and water immersion time on the shear strength and fatigue life of the composite beams were analyzed. The water damage mechanism of the composite beams under different water sources was determined by laser scanning with the longitudinal profile of the beams. Results show that the effect of immersion time on the shear strength of the composite beams is greater than that of interlayer water sprinkle amount. Under the same test conditions, the logarithmic decay rate of fatigue life increases with increasing interlayer water sprinkle amount or prolonged water immersion. However, the increase trend changes depending on immersion time, that is, it obviously slows down with time. With the increase in interlayer water sprinkle amount, the bending stiffness modulus loss of the composite beams increases nonlinearly to an amount less than 10%. Moreover, the bending stiffness modulus loss increases gradually with prolonged water immersion. It reaches 31% and then stabilizes after 5 days. Laser scanning shows that interlayer sprinkling creates a small gap in the interstitial interface of the composite beams, whereas water immersion forms a large area of peeled aggregate inside the upper interface mix. These results indicate that water immersion causes serious damage to the composite beams.