# Mechanical Behavior of Carbon Fiber-Reinforced Concrete Structures After Structural Failure
## 3 Results y Analysis
\begin{table}
\begin{tabular}{c c c c c c} \hline  & **Specimens** & \(\sigma_{\rm max}\) & \(\sigma_{\rm all}\) & \(\epsilon_{\rm max}\) & \(\epsilon_{\rm all}\) \\  & **(N/mm\({}^{2}\))** & **(N/mm\({}^{2}\))** & **(N/mm\({}^{2}\))** & **(\(\epsilon_{\rm all}\))** \\ \hline Type I \(\geq\) 15 & SA & 16.24 \(\pm\) 0.67 & 5.23 \(\pm\) 0.43 & 0.0027 \(\pm\) 0.003 & 0.0042 \(\pm\) 0.006 \\ N/mm\({}^{2}\) & PP & 18.93 \(\pm\) 0.78 & 6.09 \(\pm\) 0.35 & 0.0032 \(\pm\) 0.002 & 0.0047 \(\pm\) 0.001 \\ \hline Type II \(\leq\) 15 & SA & 12.62 \(\pm\) 0.52 & 4.11 \(\pm\) 0.50 & 0.0023 \(\pm\) 0.004 & 0.0040 \(\pm\) 0.008 \\ N/mm\({}^{2}\) & PP & 13.60 \(\pm\) 0.52 & 4.09 \(\pm\) 0.18 & 0.0025 \(\pm\) 0.001 & 0.0045 \(\pm\) 0.004 \\ \hline \end{tabular}
\end{table} 
Table 2: Most representative average values from the compression test on concretes with and without polypropylene fibers prior to reinforcement. the unidirectional reinforcement performs better, significantly enhancing the ductility of the concrete. Table 4 shows the results of the most representative graphs from the compression test on concrete with polypropylene fibers, based on the type of concrete. It can be observed that reinforcements with unidirectional fabrics achieve the highest strengths and the greatest strain increments, which implies an improvement in the ductility of the concrete. As observed in Figure 4, all failures of the reinforced specimens are brittle, yet they exhibit significantly higher strength and energy absorption capacity compared to the unreinforced specimens [36]. The unreinforced specimens strengthened with unidirectional fiber experience a very violent brittle failure, whereas those reinforced with bidirectional fiber fail in a brittle manner but retain their structure. In concretes with polypropylene fibers, despite the brittle failure, the fragments remained connected, maintaining the cohesion of the specimen. Figure 3: Tensile strength–strain curves in concretes with the addition of polypropylene fibers. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & **Specimens** & \begin{tabular}{c} \(\sigma_{\text{max}}\) \\ **(N/mm2)** \\ \end{tabular} & **(\%)** & \begin{tabular}{c} \(\sigma_{\text{ult}}\) \\ **(N/mm2)** \\ \end{tabular} & **(\%)** & \
\begin{tabular}{c} \(\varepsilon_{\text{max}}\) \\ **(\%)** \\ \end{tabular} & **(\%)** &
\begin{tabular}{c} \(\varepsilon_{\text{ult}}\) \\ **(\%)** \\ \end{tabular} & **(\%)** \\ \hline \multirow{4}{*}{Type I} & SA-2-U 300 & 40.81 \(\pm\) 1.17 & 195 & 40.81 \(\pm\) 1.17 & 636 & 0.007 \(\pm\) 0.04 & 192 & 0.007 \(\pm\) 0.04 & 90 \\  & SA-2-U 600 & 62.21 \(\pm\) 0.27 & 288 & 62.21 \(\pm\) 0.27 & 1187 & 0.015 \(\pm\) 0.003 & 415 & 0.015 \(\pm\) 0.003 & 259 \\  & SA-1-BI 230 & 30.05 \(\pm\) 0.41 & 101 & 30.05 \(\pm\) 0.41 & 570 & 0.007 \(\pm\) 0.01 & 163 & 0.007 \(\pm\) 0.01 & 48 \\  & SA-2-BI 360 & 31.91 \(\pm\) 0.85 & 66 & 31.91 \(\pm\) 0.85 & 450 & 0.006 \(\pm\) 0.01 & 70 & 0.006 \(\pm\) 0.01 & 15 \\ \hline \multirow{4}{*}{Type II} & SA-5-U 300 & 52.39 \(\pm\) 0.38 & 328 & 52.39 \(\pm\) 0.38 & 964 & 0.009 \(\pm\) 0.09 & 327 & 0.009 \(\pm\) 0.09 & 145 \\  & SA-5-U 600 & 64.41 \(\pm\) 0.89 & 464 & 64.41 \(\pm\) 0.89 & 1778 & 0.016 \(\pm\) 0.02 & 670 & 0.016 \(\pm\) 0.02 & 603 \\  & SA-4-BI-230 & 30.21 \(\pm\) 0.61 & 97 & 30.21 \(\pm\) 0.61 & 557 & 0.005 \(\pm\) 0.09 & 104 & 0.005 \(\pm\) 0.09 & 40 \\  & SA-6-BI 360 & 38.35 \(\pm\) 0.23 & 214 & 38.35 \(\pm\) 0.23 & 944 & 0.008 \(\pm\) 0.007 & 244 & 0.008 \(\pm\) 0.007 & 106 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Test results of reinforced specimens without the addition of polypropylene fibers. In Figure 5, it can be observed that the greatest strength increases in confined specimens compared to unconfined specimens occur in concretes with stresses below 15 N/mm\({}^{2}\) (Type II), both in concretes with and without polypropylene fibers and in concretes reinforced with higher weight unidirectional fabrics.