An Effective Thixotropic Structural-Dynamics Rheological-Model for 3D Printed Concrete Materials in the Flow-State (2024-09)¶

3D-printed concrete technology has recently gained significant attention due to its numerous benefits. The key factors for successful printing and molding include proper printability, which encompasses fluidity, pumpability, and plasticity. An accurate rheological model can offer insights into these changes, playing a critical role in monitoring and predicting concrete behavior and ensuring efficient and orderly construction. This paper presents a novel thixotropic structural dynamics model derived from a detailed analysis of concrete 3D printing flow characteristics. The model describes the elastic deformation of 3D-printed concrete materials using a new elastic strain evolution equation and represents the structural evolution during the flow process with a structural parameter equation. Comparison with experimental results demonstrates that the proposed model accurately captures the flow behavior of 3D-printed concrete materials. Moreover, the associated parameters effectively reflect the evolution of elastic strain and structural changes in line with the physical mechanism. This model not only describes the rheological properties of 3D-printed concrete but also aids in selecting optimal process parameters for 3D printing.