The research focuses on the development of a new generation of 3D-printed cementitious materials with enhanced performance. Layered, 3D-printed concrete components are being developed in infrastructure and housing construction. However, broad adoption of these components by the construction industry is impeded by less-than-satisfactory mechanical properties and durability. The research will achieve a foundational understanding of the physics of 3D-printed concrete in several temporal and spatial scales and will answer fundamental questions about the mechanisms involved in the extrusion process. The knowledge will then be used to inform designs of the internal architecture of the material with the goal of tailoring fracture response and transport behavior. By engineering the weak attributes of the interfaces with internal helical architectures, this research aims to enhance mixed-mode fracture toughness in 3D-printed cementitious materials based on fracture mechanics principles. In response to the world's growing population, this research aims to contribute to the development of resilient and sustainable civil infrastructure.