## 2 Materials and Methods  
### Properties of Selected Textiles, Considered Layups and Matrix  
Three different TRC systems were compared in this study: a knitted 3D, a woven 3D and an equivalent 2D TRC system (Figure 1). The 2D textiles required for the equivalent 2D TRC layup were obtained by cutting through the knitted 3D textiles and therefore removing their transversal connections. The knitted (Figure 2) and the woven (Figure 3) 3D textiles differed at the following levels. Firstly, as can be seen in Table 1, the grid size of the knitted 3D textile was larger than the woven 3D textile. The 2400 tex yarns of the knitted textile (compared to 1200 tex for the woven textile), however, compensated for the larger grid size, leading to equal textile densities for both configurations and therefore the same unidirectional fiber volume fraction (1.49%). Conversely, the knitted 3D textiles were styrene-butadiene coated. Previous studies have shown that coated textiles led to better mechanical anchorage within the matrix and therefore improved post-cracking stiffness and pull-out stress at failure [20; 23; 24; 25]. [PERSON] et al. [23] concluded that coating multifilament carbon yarns improves mechanical behavior and bonding of the composite compared with non-coated carbon yarn composites. [PERSON] et al. [24] observed a promising enhancement of the bond between fabric and matrix, even with the use of low percentages of coating resin. [PERSON] et al. [25] highlighted the increased matrix-to-fabric strength due to epoxy coating in inorganic composites. Additionally, since the woven 3D textiles possessed continuously woven (polyester) transversal connections along the y-axis, these connections were intertwined with the in-plane yarns. The in-plane yarns along the y-axis were therefore not straightened but warped, while the werf yarns along the x-axis were straightened (Figure 3). A different behavior for this woven textile was therefore expected when loaded along the x- and the y-axis, respectively. The knitted 3D textile did not possess this orientation-dependency from the in-plane yarns, since the connections were discretely knitted and did not impact the in-plane textiles' configuration. In addition, the discrete transversal connections of the knitted 3D TRC were not  
The 3D textiles were inserted in TRC specimens of 22 mm height and 4.25 mm concrete cover at both sides. The interdistance between the textile layers was 8.5 mm for all layups. For both considered 3D textiles, two outer 2D textile layers (Figure 4) were added: one on top and one at the bottom (see the white colored textiles in Figure 1a-c. These additional 2D textile layers were added to achieve a fiber volume fraction beyond the critical one. Without this addition, the unidirectional fiber volume fraction would have been too low (0.56%) to warrant a post-cracking behavior of the TRC [26]. Therefore, two additional 2D TRC layers were manually knitted on top of the 3D textiles, resulting in a TRC with a unidirectional fiber volume fraction of 1.49%. The selected cementitious matrix was a commercially available grout which was chosen for its low viscosity in fresh state, in order to be pourable during the manufacturing process. Additionally, the maximum aggregate size of 1.6 mm allowed the 3D textiles to be fully interpenetrated. The main properties of the selected mortar [27] are summarized in Table 2. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Textile** & **Material** & **Grid Size** & **Textile Density** & **Equivalent** & **Yam** & **Textile Max** & **Transversal** \\  & **(mm \(\times\) mm)** & **Textile Density** & **Thickness** & **Stiffness** & **Stress (MPa)** & **Connection** \\ \hline Knitted 3D & AR-glass 2400 tex & 22.5 \(\times\) 22.5 & 536 & 0.105 & 67 & 496 & knitted polyester \\ Woven 3D & AR-glass 1200 tex & 9.1 \(\times\) 9.1 & 527 & 0.103 & 67 & 512 & woven polyester \\
2D & AR-glass 2400 tex & 17.5 \(\times\) 17.5 & 568 & 0.223 & 67 & 526 & / \\ \hline \hline \end{tabular}
\end{table}