## 3 Results
### Comparison of Results  
Figures 6 and 7 illustrate the relationship between the experimental and theoretical critical moments for all tested beams. A ratio above 1 represents a conservative estimation, while a ratio below 1 indicates a value greater than the experimentally predicted.  
The \(M_{crcr}/M_{orth}\) ratios obtained for N100, CR50, and CR100 were 1.11, 1.04, and 0.99, respectively, according to the ACI 318 code, while the Eurocode 2 ratios were 1.29, 1.21, and 1.18, respectively. The \(M_{aver}/M_{orth}\) ratios obtained for N100, CR50, and CR100 were 1.84, 1.58, and 1.54, respectively, according to the ACI 318 code, while the Eurocode 2 ratios were 1.58, 1.38, and 1.35, respectively.  
For the critical moment, the prediction of the ACI 318 code was closer to the experimental results. In the case of high replacement percentages (100%), the experimental values were slightly below the theoretical values (0.99). Eurocode 2 yielded a more conservative prediction (1.18). The ACI 318 was more conservative than Eurocode 2 for the end moment prediction.  
\begin{table}
\begin{tabular}{c l c c c} \hline  & & **N100** & **CR50** & **CR100** \\ \hline \multirow{3}{*}{\(P_{\alpha}\) (kN) 1  & Experimental & 237.66 & 202.80 & 193.95 \\  & & & 129.22 & 128.47 & 125.74 \\  & & & 148.26 & 147.13 & 143.52 \\ \hline \multirow{3}{*}{\(P_{\alpha}\) (kN) 2  & Experimental & 32.95 & 30.32 & 27.85 \\  & & & 29.60 & 29.23 & 27.96 \\  & & & 25.54 & 25.08 & 23.57 \\ \hline \multirow{3}{*}{\(M_{\alpha}\) (kN) 3  & Experimental & 71.30 & 60.84 & 58.19 \\  & & & 38.77 & 38.54 & 37.72 \\  & & & 44.48 & 44.14 & 43.06 \\ \hline \multirow{3}{*}{\(M_{\alpha}\) (kN) 4  & Experimental & 9.89 & 9.10 & 8.36 \\  & & & 8.88 & 8.77 & 8.39 \\  & & & 7.66 & 7.52 & 7.07 \\ \hline \multirow{3}{*}{\(\delta_{\alpha}\) (kN) 5  & Experimental & 3.12 & 3.20 & 3.18 \\  & & & 3.87 & 3.86 & 3.84 \\  & & & 4.49 & 4.47 & 4.42 \\ \hline \multirow{3}{*}{\(\delta_{\alpha}\)(kN) 6  & Experimental & 1.05 & 1.08 & 1.10 \\  & & & 0.89 & 0.88 & 0.85 \\  & & & 0.77 & 0.76 & 0.73 \\ \hline \end{tabular}  
* 1 \(P_{\alpha}\): Ultimate Load, 2 \(P_{\alpha}\): Cracking Load, 3\(M_{\alpha}\): Ultimate Moment, 4\(M_{\alpha}\): Cracking Moment, 5\(\delta_{\alpha}\): Ultimate Deflection, 6 \(\delta_{\alpha}\): Cracking Deflection.  
\end{table}
Table 7: Test results of the studied beams compared to ACI 318-19 and Eurocode 2.  
Figure 6: Relationship between the experimental and theoretical cracking moments (\(M_{cr}\)).  
Figures 8 and 9 shows the relation between the experimental and theoretical critical and end strains of the studied beams. It can be observed that Eurocode 2 was more conservative in calculating the critical strain; at the same time, both codes overestimated the calculation of the end strains of all series [46].  
The \(\delta_{\mathit{crep}}/\delta_{\mathit{crth}}\) ratio obtained for the N100, CR50, and CR100 beams was 1.18, 1.24, and 1.29, respectively, according to the ACI 318 code. However, according to Eurocode 2, they were 1.36, 1.44, and 1.52, which shows that the critical strain increases with increasing use of recycled aggregates, mainly due to the lower modulus of elasticity of these series.  
The \(\delta_{\mathit{ucxp}}/\delta_{\mathit{uth}}\) ratio obtained for N100, CR50, and CR100 was 0.81, 0.82, and 0.83, respectively, when using the ACI318 code, while they were 0.69, 0.70, and 0.72 when using the Eurocode 2.  
Figure 8: Relationship between experimental and theoretical cracking deflection values (\(\delta_{\mathit{cr}}\)).  
Figure 7: Relationship between the experimental and theoretical ultimate moments (\(M_{\mathit{u}}\)).