Overlay Test to Investigate the Crack Propagation of a Large-Size Asphalt Mixture: Fid-Bau Portal

Overlay Test to Investigate the Crack Propagation of a Large-Size Asphalt Mixture

Wei, Jianhui / Shi, Junjie / Liang, Junlin

The crack propagation of a large-size asphalt mixture (LSAM) with three temperatures, three asphalt aggregate ratios, three displacements, and short-term and long-term aging is investigated by an improved overlay test (OT). Based on the concept of pseudodisplacement and finite element simulation, a method for evaluating the fracture performance and crack propagation of LSAM is proposed in this paper. The crack propagation length can be obtained by calculating the relative pseudosecant stiffness. The results show that: (1) a power function can describe the crack growth of LSAM, and the rate of crack growth is larger at the initial stage of loading and gradually decreases with an increase in load cycles; (2) increasing the displacement, decreasing the temperature, and increasing the aging time significantly increases the crack growth rate of LSAM, but the variation in asphalt aggregate ratios does not have a significant effect on the crack growth rate of LSAM; and (3) the stress intensity factor decreases with an increase in crack length, and the stress intensity factor and the fracture properties parameters ( $n$ ) increase with an increase in displacement, a decrease in temperature, and an increase in aging time.