# Mechanical Behavior of Carbon Fiber-Reinforced Concrete Structures After Structural Failure
## 2 Materials and Methods
Subsequently, water and the admixture were added, and the mixture was processed for five minutes until a plastic consistency of the concrete was achieved. The concrete was then poured into the molds in accordance with the standard for fresh concrete testing (UNE-EN 12390-3) [45]. The molds were leveled and kept at laboratory ambient temperature, approximately 22 \(\pm\) 3 \({}^{\circ}\)C, and a relative humidity of approximately 60% for 24 h before demolding. After 24 h, the specimens were removed from the molds and stored in a curing chamber at a temperature of 20 \(\pm\) 2 \({}^{\circ}\)C and a relative humidity of \(\geq\)95% for 28 days for curing and hardening. The fibers used for the study, supplied by the company MAPEI SPAIN S.A, have different morphologies. One type of fiber is unidirectional, and the other type is bidirectional. For each type of fiber, strips were cut with dimensions of 180 \(\times\) 420 mm, with an overlap of 100 mm, meaning that each strip has a length of 180 mm and a width of 420 mm, with a 100 mm overlap at the end. For the application of the carbon fiber on the concrete specimen, it was ensured that the surface of the specimens was clean, free of dust or foreign elements. Next, a first thin layer of resin was applied to the entire surface of the specimen using a roller. Immediately after, the carbon fiber was placed over the resin, and a second layer of resin was applied using a trovel, thereby confining the entire specimen. Finally, pressure was applied to the fiber to remove any excess resin that had been applied Figure 1a. Once the specimens had cured, compression testing was carried out on reference specimens (with and without polypropylene fibers), which were then reinforced and retested under compression. The process of reinforcing the specimens with carbon fiber fabric and their subsequent compression testing is illustrated in Figure 1b. \begin{table}
\begin{tabular}{c c c c c c} \hline
**Specimens/** & **UNI AX-300** & **UNI AX-600** & **Specimens/** & **UNI AX-300** & **UNI AX-600** \\
**Type of Fibers** & **AN-1-U 300** & **AN-1-U 600** & & PP-1-U 300 & PP-1-U 600 \\  & **AN-2-U 300** & **AN-2-U 600** & **Type I Stresses** & PP-2-U 300 & PP-2-U 600 \\  & **AN-3-U 300** & **AN-3-U 600** & & PP-3-U 300 & PP-3-U 600 \\  & **AN-4-U 300** & **AN-4-U 600** & & PP-4-U 300 & PP-4-U 600 \\  & **AN-5-U 300** & **AN-5-U 600** & **Type II Stresses** & PP-5-U 300 & PP-5-U 600 \\  & **AN-6-U 300** & **AN-6-U 600** & & PP-6-U 300 & PP-6-U 600 \\ \hline Specimens/ & \multirow{2}{*}{BI AX-230} & \multirow{2}{*}{BI AX-360} & Specimens/ & \multirow{2}{*}{BI AX-230} & \multirow{2}{*}{BI AX-360} \\ Type of Fibers & & & Type of Fibers & & \\ \hline  & **AN-1-BI 230** & **AN-1-BI 360** & & PP-1-BI 230 & PP-1-BI 360 \\ Type I Stresses & **AN-2-BI 230** & **AN-2-BI 360** & **Type I Stresses** & PP-2-BI 230 & PP-2-BI 360 \\  & **AN-3-BI 230** & **AN-3- BI 360** & & PP-3-BI 230 & PP-3-BI 360 \\  & **AN-4-BI 230** & **AN-4-BI 360** & & PP-4-BI 230 & PP-4-BI 360 \\ Type II Stresses & **AN-5-BI 230** & **AN-5- BI 360** & **Type II Stresses** & PP-5-BI 230 & PP-5-BI 360 \\  & **AN-6-BI 230** & **AN-6-BI 360** & & PP-6-BI 230 & PP-6-BI 360 \\ \hline \end{tabular}  
* SA: concrete specimens without the addition of polypropylene fibers; PP: concrete specimens with the addition of polypropylene fibers; BI: type of bidirectional carbon fiber fabric with balanced weight; U: type of bidirectional carbon fiber fabric with balanced weight; 300 /600 /230 /360: weight of the carbon fiber.  
\end{table} 
Table 1: The nomenclature of concrete test specimens with and without polypropylene fibers, with the four types of reinforcement fabrics.