## 2 Experimental Design  
### Specim Overview  
Nine one-way slab specimens reinforced with carbon grids were prepared to evaluate their flexural behavior; Table 1 summarizes the specifications of different parameters of the specimens. The primary experimental variables were the cross-sectional area (1.7, 1.8, 3.5, 17.5, 26.4, 65, and 100 mm\({}^{2}\)), spacing (21, 38, 50, and 100 mm), tensile strength (1200, 1400, 3600, and 4000 MPa), and elastic modulus (100, 165, and 230 GPa) of strands according to the carbon grid-manufacturing method (biaxial warp-knitted and cross-laminate structures). For comparison, a one-way slab specimen reinforced with steel was also prepared. Typically, carbon grids are chemically stable [7] and exhibit high resistance to corrosion caused by chloride attacks; consequently, a minimum cover depth is not necessary to prevent chloride attacks [21]. Therefore, a cover depth of less than 10 mm was set for the specimens reinforced with carbon grids in this study. The size of the carbon grid-reinforced specimens (Figure 2a-c) was determined so that the failure mode was governed by mortar crushing considering the universal testing machine (UTM) condition. The size of the steel-reinforced specimen (Figure 2d) was also determined so that the tensile capacity by reinforcement was similar to the specimens reinforced with both the biaxial warp knitted and cross-laminate structured carbon grids. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Specimen**} & \multirow{2}{*}{**Width (mm)**} & \multirow{2}{*}{**Depth (mm)**} & \multirow{2}{*}{**Length (mm)**} & \multicolumn{2}{c}{**Carbon Grid**} \\ \cline{5-6}  & & & & & **Number of** & **Maximum Tensile** \\  & & & & **Longitudinal** & **Load by Grids or** \\  & & & & & **Direction Grids** & **Steel (KN)** \\ \hline G1 & & & & Q95 & 8 & 101.3 \\ G2 & & & & Q85 & 15 & 106.3 \\ G3 & & & & Q47 & 8 & 50.1 \\ J1 & & & & FTG-CR6 & 3 & 73.5 \\ J2 & & 50 & 1000 & FTG-CR8\_50 & 5 & 184.8 \\ J3 & & & & FTG-CR8 & 3 & 110.9 \\ J4 & & & & FTG-CR13 & 3 & 273.0 \\ J5 & & & & FTG-CR16 & 3 & 420.0 \\ J6 & & & & FTG-CRR16 & 3 & 360.0 \\ RC & & 65 & & (Steel, D10) & 3 & 85.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Specifications of the one-way slab specimens. Figure 2: Specimens reinforced by: (**a**) Q95 and Q47; (**b**) Q85; (**c**) FTG-CR6, FTG-CR8_50, FTG-CR8, FTG-CR13, FTG-CR16, and FTG-CMR, and (**d**) steel. Two types of structures, produced by different manufacturing methods, were observed in the carbon grids. The first was a biaxial warp-knitted structure, hardened by epoxy resin impregnation. Herein, the carbon fiber strands were pulled in the weft and warp directions, and separate fibers were woven in the warp direction (Figure 3a) [16]. Conversely, a cross-laminate structured carbon grid was manufactured by laminating thin strips of carbon fibers in the weft and warp directions and hardening them by vinyl ester resin impregnation (Figure 3b). Table 2 lists the primary characteristics of these carbon grids. The biaxial warp-knitted structured carbon grid exhibited a higher tensile strength and elastic modulus than the cross-laminate structured carbon grid; however, the spacing and cross-sectional area of strands was smaller in the former. On the other hand, SD400-D10 was used in the steel-reinforced specimen that was compared to the carbon grid-reinforced specimens, and its tensile properties are presented in Table 2.  
The strand spacings of the carbon grids were 21, 38, 50, and 100 mm; except for the 100-mm-spacing, concrete with coarse aggregate could not be appropriately poured between strands. Therefore, the specimens were prepared using mortar, which did not use coarse aggregate [20; 22]. Table 3 presents the mortar mix design and the compressive strength of mortar at 28 days. In the case of specimens reinforced with the carbon grids, the mortar was initially poured to the height corresponding to the cover thickness.