3D-printed ultra-high-performance concrete (3DP-UHPC), which combines high strength, high toughness, and construction flexibility, provides a solution to the reinforcement difficulty of conventional printed concrete. However, the layer-by-layer printing process induces pronounced anisotropy in compressive and flexural properties, which remains a key challenge for engineering applications. We used X-ray computed tomography (X-CT) to quantitatively analyse the internal pores and to reveal the orientation and distribution of steel fibres in 3DP-UHPC. Splitting tensile tests showed that the interlayer splitting tensile strength is approximately 49.3% lower than the conventional splitting tensile... More >