The splitting fatigue properties of ultra-large particle size asphalt mixture under the coupling effect of temperature and load

In this work, the ultra-large particle size asphalt mixture (LSAM-50) was initially molded through the vertical vibration test method, producing cylindrical specimens. Subsequently, the influence of temperature, oil-to-aggregate ratio, and maximum aggregate particle size on the splitting properties was meticulously examined through splitting tests. This investigation culminated in the construction of a temperature-dependent model for this mechanical property. Furthermore, the impact of temperature and stress levels on the splitting fatigue performance was probed, leading to the development and verification of a fatigue equation for LSAM-50 under the combined effect of temperature and load, which was confirmed through indoor fatigue tests conducted at low stress levels. The findings revealed a notable trend: the splitting tensile strength and failure stiffness modulus diminish as temperature increases, with the rate of decrease gradually slowing over time, and the failure tensile strain exhibits an opposing trend. Across a spectrum of temperatures, the splitting tensile strength of asphalt mixtures tends to enhance as the maximum aggregate particle size increases. The cohesive force, denoted as 'c,' presents an 'inverse S-shaped' curve with escalating temperature, while the internal friction angle, represented by 'phi,' remains relatively stable with temperature fluctuations. The Boltzmann function emerges as an effective means to characterize the temperature dependency of the splitting characteristics, boasting an R2 value exceeding 0.98. The splitting fatigue life progressively diminishes with the increase in temperature (or stress level), with the fatigue equation under the combined influence of temperature and load expressed as lgN=(4.72-0.076T)-(3.12-0.027T)lg(6-6th), where the fatigue limit 6th = 0.072e-0.046T and R2 > 0.85. The overall pattern of LSAM-50 ' s splitting fatigue life in the low stress region aligns with the curve described by the fatigue equation. The outcomes of this research have laid a solid foundation for the design of LSAM-50, offering invaluable insights into its performance characteristics under various conditions.