Fatigue Performance of Double-Layer Beams with an Interlayer Based on the Method of Equivalent Fatigue Life

Abstract

The bonding performance between a thin overlay and the pavement is an important basis for good performance of asphalt pavement. To research the effect of interlayer bonding on the fatigue life of thin overlays, three-point bending fatigue test was carried out on the double-layer beams with interlayer (DLBI). The equivalent fatigue life obtained by the Weibull distribution function was used to analyze the influence of stress ratio, loading frequency, immersion times, and freeze–thaw cycles on the fatigue life. The results suggest that the fatigue performance of DLBI was affected significantly by stress ratio, loading frequency, immersion times, and freeze–thaw cycles. The higher the loading frequency, the greater the effect of the stress ratio on the fatigue performance of the DLBI. The lower the stress ratio, the greater the effect of the loading frequency on fatigue performance of the DLBI. The fatigue life of the DLBI declined by 31.4% and 24.7% after 6 immersion days and five freeze–thaw cycles, respectively. The damage to DLBI caused by one freeze–thaw cycle was equivalent to that caused by 4 days of immersion. Models that take into account four kinds of environment factors to equivalent fatigue life prediction based on 50% failure probability and 5% failure probability, respectively, are proposed, with the equivalent fatigue life method. Taking the equivalent fatigue life as the indicator, the DLBI crack length expansion model is obtained, and the axle load conversion coefficients considering the influence of dynamic loads and adverse seasons factors are calculated. A method is proposed to judge the fracture of double-layer beams.