# Mechanical Strength Characterization of Plastic Fiber Reinforced Cement Concrete Composites
## 3 Results
### Flexural Characteristics  
The exclusive test parameters evaluated based on the flexural bending results are provided in Table 7 and the significant effects of randomly/homogenously distributed (full concrete volume) versus tension zone confined fiber concretes are discussed in this section. The fiber alignment showed significant effects on the stress sharing during flexural bending. Additionally, in this study, the effects of fiber alignment in the tension zone showed maximum improvements on the flexural bending accompanied by increased flexural stress capacity. The fiber reinforcements showed real merits in terms of load resistance upon cracking without any sudden drop in load resistance. The discrete plastic fibers distributed in the concrete matrix homogeneously and confined in the tension zone were systematically evaluated using different experimental parameters. The importance of plastic fibers was convincing in improving the first crack strength of plain concrete, which  
Figure 12: Relationship between the compressive strength index vs. fiber performance index.  
can be noted from the load-crack mouth opening displacement (CMOD) curves provided in Figure 13.  
Compared to full depth homogeneous fiber concrete, the first crack strength was evidently improved in the tension zone confined concrete. The maximum first crack strength of 4.89 N/mm\({}^{2}\) was observed for the PFC-10T concrete mix. It is well noted that the tension zone confined plastic fiber concrete consistently performed in all the flexural parameters evaluated. It is apparently evident that the flexural strength and residual flexural strength were increased in all tension zone confined fiber concretes compared to the homogenous fiber concretes. The effect of fiber alignment and confinement in tension zone had more pronounced effects on the flexural performance as the fibers were effectively strained along the bending axis. Hence, the stress transfer mechanism was readily shared in direct fiber alignment along the bending plane. A maximum flexural toughness of 33.43 N/mm\({}^{2}\) was obtained in PFC-15T and the toughness was notably increased at higher fiber volume fraction. It can be well derived from the test results that the toughness of higher volume fiber concrete is greatly improved. However, the confinement of fiber volume at lower fiber fraction showed consistent improvement on the overall flexural response  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{3}{*}{**Mix ID**} & **First Crack Strength** & **Flexural Strength** & **Crack Strength** & **Residual** & **Flexural** & **Post** & **Flexural** & **Fiber Strength** & **Fiber** \\  & **(N/mm\({}^{2}\))** & **Flexural Strength** & **Width(mm)** & **Strength Capacity** & **Toughness** & **Load Resistance** & **Resistance** & **Increase** \\  & **(N/mm\({}^{2}\))** & & & **(N/mm\({}^{2}\))** & & **(N/mm\({}^{2}\))** & **(\%)** & **(\%)** & **(\%)** \\ \hline RCM-30 & 3.72 & 3.8 & 1.25 & 0 & 0 & 0 & - & - \\ \hline PFC-05H & 3.89 & 4.12 & 1.54 & 2.05 & 5.39 & 65.2 & 8.42 & 73.62 \\ \hline PFC-10H & 4.17 & 4.36 & 1.86 & 3.18 & 15.39 & 73.3 & 14.74 & 88.04 \\ \hline PFC-15H & 3.95 & 4.2 & 1.8 & 3.21 & 20.78 & 88.4 & 10.53 & 98.93 \\ \hline PFC-05T & 4.27 & 4.72 & 2.12 & 2.98 & 10.42 & 90.9 & 24.21 & 115.11 \\ \hline PFC-10T & 4.89 & 5.26 & 2.75 & 4.18 & 29.57 & 93.7 & 38.42 & 132.12 \\ \hline PFC-15T & 4.51 & 4.85 & 3.15 & 4.37 & 33.43 & 96.2 & 27.63 & 123.83 \\ \hline \hline \end{tabular} Note: Test results denote the average of five concrete specimens tested for each concrete mix type.  
\end{table}
Table 7: Flexural evaluations of various plastic fiber incorporated concretes.  
Figure 13: Load-CMOD curves for various plastic fiber incorporated concrete mixes.  
compared to the homogenously distributed plastic fiber concrete systems. The maximum response values obtained from the various flexural parameters are discussed below