Fatigue Behavior of Bitumen-bound Materials in Nonstandard Temperature Conditions

Abstract The thermal sensitivity of bitumen-bound materials is a well-documented phenomenon. Variations in temperature significantly alter the mechanical response of asphalt mixtures, transitioning their behavior from predominantly elastic to viscous, and affecting parameters such as complex modulus, phase angle, and other rheological characteristics. This investigation evaluates the influence of elevated and reduced temperatures on the fatigue performance of an asphalt mixture intended for road surface layers. Experimental assessments were conducted using the four-point bending test on an asphalt concrete with a nominal maximum aggregate size of 11 mm, incorporating polymer-modified bitumen. The high-temperature condition was set at 27 °C, in accordance with the Slovak pavement design methodology, while the low-temperature condition was defined at 5 °C, constrained by the operational limits of the testing apparatus. Standard fatigue testing temperatures, as stipulated by European specifications, include 10 °C, 15 °C, and 20 °C. Material structural evolution under cyclic loading was analyzed via energy dissipation calculations per loading cycle. The primary objective of this study was to characterize the mechanical response of the asphalt mixture under non-standard thermal conditions.