## 4 Conclusions  
In this study, we conducted experimental and theoretical research on the flexural behavior of concrete beams with RA. Three concrete beams reinforced with different percentages of coated recycled aggregate (0%, 50%, and 100%) were tested. The structural characteristics predicted by the ACI 318-19 and Eurocode 2 codes were assessed. Based on the results, the following conclusions can be drawn:  
* When using the RA, the compressive strength decreased by 3.00% with 50% replacement and 12.73% with 100% replacement, whilehe flexural strength decreased by 8.44% with 50% replacement and 16.62% with 100% replacement. Although the treatment showed slight improvements in the physical properties, inferior results were obtained in terms of the mechanical properties, which could be linked to the different w/c ratios used to ensure the workability of the mixtures and comply with the requirements of industry.
* The use of enhanced RA revealed a similar cracking pattern in terms of the number and spacing of cracks, indicating that the beams failed in a similar manner.
* Increasing the percentage of RA reduced the load capacity; in addition, it reduced the end moment by 14.67% and the failure moment by 7.98% for the 50% replacement. For the 100% replacement, the end moment was reduced by 18.39% and the failure moment by 15.48%. For the 50% replacement, the end deflection in the central third was increased by 2.56% and the critical deflection was decreased by 25.71%. Conversely, when 100% replacement was used, the end and critical deflection both increased, by 1.92% and 4.76%, respectively.
* The theoretical results provided by the equations in the Eurocode 2 and ACI 318-19 codes were compared with the experimental results. The most conservative critical moment standard was Eurocode 2; however, all the experimental critical moments were higher than the theoretical ones, with the exception of the critical moment calculated using ACI 318-19 for the 100% replacement, which resulted in a ratio of approximately 1.
* The beams with RA had higher critical and end load capacities than the results predicted by the Eurocode 2 and ACI 318-19 codes, indicating that the moment capacity can be estimated using these design.  
Figure 9: Relationship between experimental and theoretical ultimate deflection values (\(\delta_{u}\)).  
It should be noted that our study was limited to the situation described above, i.e., the use of low-quality recycled aggregates. It is recommended that further studies be carried out in order to validate the results obtained in the present study.  
Conceptualization, V.L.; methodology, V.L.; formal analysis, C.M.; investigation, V.L. and B.W.; resources, V.L.; data curation, V.L. and B.W.; writing--original draft preparation, C.M.; writing--review and editing, V.L. and B.W.; supervision, V.L.; project administration, V.L.; funding acquisition, V.L. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Agency for Research and Development (ANID) under grant number FONDECYT REGULAR 1211135.  
Not applicable.  
The original contributions presented in the study are included in the article; further inquiries can be directed to the corresponding author.  
The authors gratefully acknowledge the partial support from the Universidad de La Frontera (Chile) and Ministerio de Educacion (MINEDUC) (Project FRO2395).  
The authors declare no conflicts of interest.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Beam** & \(M_{tr}\) (kN \(\cdot\) m) & \(I\) (m) & \(P_{cr}\) (kN) \\ \hline N100 & 8.88 & 6 & 29.60 \\ CR50 & 8.77 & 6 & 29.23 \\ CR100 & 8.39 & 6 & 27.96 \\ \hline \hline \end{tabular}
\end{table}
Table 7: Calculation memory for theoretical critical load (Eurocode 2).