Abstract: Tensile mechanical properties of hydraulic asphalt concrete are crucially important to an in-depth study of the tensile cracking failure of impervious structures of high rockfill dams. Aiming at the existing problems in the direct tensile test of hydraulic asphalt concrete, we developed a direct tensile test instrument with temperature control, and conducted axial direct tensile tests of hydraulic asphalt concrete in the temperature from -30 ℃ to 15 ℃. Based on the Mohr-Coulomb criterion, variations in cohesion and internal friction angle with temperature were analyzed. Results show that the relationship between tensile stress and strain is approximately linear at temperature below 0 ℃, and the specimen reaches the peak stress and then fractures. While at higher temperature, it experiences a certain degree of plastic deformation and then fractures upon reaching the peak stress, with the deformation range increasing with temperature rising. As temperature rises from -30 ℃ to 15 ℃, tensile strength and cohesion increase first and then decrease, both peaking at -20 ℃. With temperature rising, tensile modulus decreases while critical strain increases; internal friction angle decreases first and then increases, with a trough at 0 ℃; The proportion of aggregate cracking at the specimens’ surface decreases. This study verifies the empirical formula proposed in this paper is in good agreement with the experimental results and well reflects the variations in tensile strength, tensile modulus, peak strain, cohesion, and internal friction angle with temperature.

Key words: hydraulic asphalt concrete, direct tension, temperature effect, strength parameter, failure mode