A Review of Recent Trends and Challenges in Numerical Modeling of the Anisotropic Behavior of Hardened 3D Printed Concrete (2024-07)¶

The rapid development of 3D printed concrete (3DPC) technology, in particular the integration of reinforcement into the components, emphasizes the need for accurate prediction of structural performance in the hardened state. This pressing need is evidenced by the emerging development of numerical models to capture the anisotropic behavior of 3DPC components in recent years. This paper reviews the current state of the art, particularly focusing on existing modeling approaches for modeling the structural performance of hardened 3DPC elements. The models are categorized into three main groups: macro-scale phenomenological continuum models, that represent the anisotropic behavior in a smeared manner; macro-scale interface-based models, that explicitly account for the interfacial behavior between printed layers; and detailed meso-scale discrete models, that account for the inherent heterogeneity of concrete. The review provides a summary of the existing models within these groups and describes their main modeling hypotheses, constitutive assumptions, underlying phenomena, presented numerical applications, as well as their strengths and limitations. In addition, experimentally available test setups and the resulting material properties are summarized, that are crucial for the calibration and potential validation of these modeling approaches. Based on experimental observations reported in the literature in the context of 3DPC and the additive manufacturing process, this paper highlights the main key challenges and outlines the need for further research and improvements in modeling approaches for 3DPC. These insights are discussed in relation to the evolving developments in modeling conventional mold-cast concrete, offering a comprehensive perspective on the present state and future directions in the field.