In this study, lightweight precast hollow core slabs made of carbon-reinforced concrete were developed to enable highly slender cross-sections and significant reductions in concrete mass. The structural system combines conventional biaxial carbon grids with an innovative 3D textile reinforcement, designed to transfer both shear and tensile forces. To demonstrate technological readiness, two large-scale slab elements (5.4 m x 2.3 m) were investigated in 4-point-bending tests. An extensive measurement program-including distributed fiber optic sensors (DFOS) and digital image correlation (DIC)-provided detailed insights into both material-level and global structural behavior. The slabs significantly exceeded the required ultimate limit state (ULS) load levels, while deformations and crack widths remained within acceptable limits under service loads throughout the tests. These results confirm the structural efficiency and applicability of carbon-reinforced hollow core slabs for lightweight, prefabricated construction.