Concrete 3D printing is an emerging digital fabrication technology that requires advanced numerical models to capture the complex rheological behavior of fresh concrete during mate-rial transport and deposition. This study presents a numerical simulation framework for con-crete 3D printing based on the Discrete Element Method (DEM), with particular emphasis on thixotropic effects. Thixotropy, defined as the reversible, time-dependent evolution of material structure under shear and rest, governs both flowability during processing and structural build-up after deposition. The proposed model is an extension of a previously developed DEM-based simulation ap-proach established at the Institute of Applied Building Research (IAB) Weimar. Building upon this foundation, the present work introduces an enhanced constitutive description to account for thixotropic behavior by incorporating a structure-dependent state variable at the particle contact level. This variable evolves according to the local shear history and resting time, ena-bling the simulation to represent structural breakdown during flow and structural recovery once shear is reduced or removed. The extended model is applied to the simulation of a novel concrete 3D printing process in which material transport is achieved exclusively through mechanically induced vibration. In contrast to conventional extrusion-based systems employing pumps or screw extruders, the investigated approach relies on vibration to temporarily reduce the apparent yield stress and promote particle rearrangement, thereby enabling continuous material flow. The DEM simula-tions capture the vibration-induced transition between solid-like and fluid-like states and pro-vide detailed insight into flow mechanisms, stability of material transport, and layer deposition behavior. The results indicate that DEM combined with a thixotropy-aware material description is well suited for analyzing vibration-driven concrete 3D printing processes. The developed frame-work provides a robust numerical tool for the systematic investigation and optimization of pump-free, vibration-based concrete extrusion technologies.