Numerical Investigation on Inter-Layer and Filament Fracture Behavior of 3D Printed Concrete (2023-09)¶

Concrete additive manufacturing is a recent emerging technology used to complete the construction through layer upon-layer deposition process. Unlike conventionally cast concrete, this automated process introduces distinct interlayers between successive layers, which leads to 3Dprinted concrete as anisotropic material. As concrete is a quasi-brittle material and prone to fracture, it is essential to study the effect of the additive manufacturing process on the fracture behavior of 3Dprinted concrete. This study uses a finite element simulation approach to examine the interlayer and filament fracture behavior of 3D-printed concrete. A scalar damage model based on isotropic continuum damage mechanics theory, is adopted to describe the failure and damage of the material, and a bilinear traction separation law-based cohesive zone model is used to account for the effect of interlayer bond characteristics of 3DPC. The printing time interval, a deposition time gap between two consecutive layers, is one of the leading printing parameters which control interlayer bond properties of 3D printed concrete. This study elucidated the impact of printing time intervals: 0 mins, 5 mins, and 10 mins on the late age load versus crack mouth opening displacement (CMOD) relation of 3DPC materials with notch locations at interlayer in one set of specimens and at filament in another set of specimens. These simulation results have good agreement with the corresponding experimental results. Further, these simulation results match the experiments at different stages of process: (1) The peak load in the interlayer notch specimen was lower than the filament notch specimen for a particular printing time interval. (2) The peak load decreases as the printing time interval increases for a particular notch position.