Multi-Scale Additive Manufacturing Of Ultra High-Performance Fiber

This study investigates the mechanical behavior of 3D-printed Ultra High Performance Concrete (UHPC) and Ultra High Performance Fiber-Reinforced Concrete (UHPFRC). It intends to contribute to the research regarding detailed experimental assurance in concrete 3D printing. Current methods are based on coring samples out of 3D printed elements, eliminating the 3D printing features. This study bridges these approaches by proposing a process to evaluate its mechanical properties that account for layered concrete's unique geometric features. A nanomodified mixture is developed to fulfill the fresh-state properties necessary for 3D printing. A flow table test validates this before printing with a piston extruder and a 3-axis gantry printer. A highly flowable mix is used as capping material to maintain surface geometry, providing a smooth, parallel loading surface for mechanical tests. Mechanical properties of the printed UHPC and UHPFRC are assessed by uniaxial compression, tensile splitting, and notched three-point bending tests. Properties of the printed samples are studied by comparing compressive and tensile strengths to cast samples from the same batch. Documentation of dimension and cause of failure included image analyses supported by 3D scanning. The test results provide valuable insight into the effects of the geometric features of 3D printed UHPC samples.