Three-dimensional Meso-scale virtual strength test of steel slag porous asphalt mixture based on PFC3D

Abstract

In recent years, steel slag has gained widespread utilization in pavement construction as a green, low-carbon building material. In this study steel slag aggregate (SSA) was used as a partial replacement for basalt aggregate in porous asphalt mixture. To gain an in-depth understanding of the microscopic cracking characteristics of steel slag aggregate porous asphalt concrete (SSA-PAC), laboratory three-point bending tests and numerical simulations were conducted. Based on CT scanning images, 3D models of SSA and basalt aggregates within particle size ranges of 4.75–9.5 mm and 9.5–13.2 mm were generated. These characteristic aggregates were then randomly placed to establish a three-dimensional model using PFC3D (Particle Flow Code in 3 Dimensions). The micro-contact parameters were derived through the conversion and calibration of macro and micro-mechanical parameters. The results of the 3D virtual strength test exhibited a close resemblance to those obtained from laboratory semi-circular bending (SCB) tests. The displacement trend chart of the aggregates revealed three distinct stages: vertical displacement, vertical displacement combined with a small amount of lateral displacement, and lateral displacement. Cracking mainly occurred at the interface between the aggregates and asphalt mortar, which aligned with actual cracking scenarios. The cracking behavior of the asphalt mixture was characterized by evaluating the number of cracks, notch width, and coordination number throughout the loading process. Additionally, the influence of loading rates on cracking behavior was analyzed. The results of this study demonstrated that the established 3D model effectively revealed the cracking characteristics of SSA-PAC.