## 4 Conclusions  
In this study, the flexural behavior of TRC one-way slabs was evaluated by performing a three-point bending test on nine carbon grid-reinforced specimens and a steel-reinforced specimen. Carbon grids manufactured by two different methods with varying cross-sectional areas, spacings, tensile strengths, and elastic moduli of longitudinal strands were incorporated into the specimens. The study findings can be summarized as follows. 1. The specimens reinforced with the biaxial warp-knitted structured carbon grids exhibited smaller crack spacings and more cracks than the specimens reinforced with the cross-laminate structured carbon grids. This was considered to be an effect of the  
Figure 19: Flexural behavior of the specimens reinforced with carbon grids and steel. Figure 18: Comparison of the maximum load between the specimens reinforced with carbon grids and steel, based on: (**a**) tensile force; and (**b**) flexural strength. smaller strand spacing of the biaxial warp-knitted structured carbon grid than that of the cross-laminated structured carbon grid. 2. The biaxial warp-knitted structured carbon grids had smaller cross-sectional areas and spacings of strands but a higher tensile strength than the cross-laminate structured carbon grids. Consequently, the specimens reinforced with the biaxial warp-knitted structured carbon grids had a lower tensile capacity than the specimens reinforced with the cross-laminated carbon grids. However, the maximum load tended to be higher in the specimens reinforced with the biaxial warp-knitted structured carbon grids than in the specimens reinforced with the cross-laminate structured carbon grids, even though the tensile capacity was similar or low. Specim G2, which had the highest tensile capacity among the specimens reinforced with the biaxial warp-knitted structured carbon grids, also exhibited a maximum load 1.10 times higher than specimen J5 which had the highest tensile capacity among all carbon grid-reinforced specimens. 3. All specimens reached the maximum load simultaneously with mortar crushing, and little damage occurred to the cross-laminated structured carbon grids by the end of the experiment. In particular, the specimens reinforced with the cross-laminated structured carbon grids seem to have used excessive carbon grids compared with the specimen conditions such as the effective depth and compressive strength of mortar. 4. When the maximum load was reached, strains corresponding to 38-82% of the tensile strain were observed on the longitudinal strands of the carbon grids. The load then decreased as the load resisted by the mortar was transferred to the carbon grids immediately after the peak. The flexural strengths calculated based on the force equilibrium and strain compatibility equations were also found to conservatively evaluate the maximum loads revealed by the experiment. 5. The load decreased immediately after the maximum load, but the load reduction stopped, or the load slightly increased, with the increasing mid-span deflection in the case of the specimens in which a stress of less than 80% of the tensile strength was applied to the longitudinal strands under the maximum load. The experimental results validate (i) the design for generating tensile stress in a carbon grid that corresponds to less than 80% of the tensile strength at the ultimate state and (ii) the requirement for a securing bond between a carbon grid and mortar to prevent brittle failures right after reaching the maximum load caused by the carbon-grid fracture. 6. Among the specimens reinforced with the cross-laminate structured carbon grids, the specimens reinforced with the stiffer carbon grids because of the largest cross-sectional areas or small spacing of strands immediately exhibited the behavior of the crack stabilization stage without crack formation. 7. Except for the stiffer carbon grid-reinforced specimens, the stiffness of the carbon grid-reinforced specimens after cracking decreased to approximately 8% or lower than those before cracking.