# Recycled Eco-Concretes Containing Fine and/or Coarse Concrete Aggregates. Mechanical Performance
## 4 Conclusions  
The conclusions obtained in this work are presented below:  
* Recycled aggregates have greater absorption, as well as lower LA coefficient, density and flakiness index than natural aggregates. * The coarse recycled fractions (gravel and gravel) and fine (sand) comply with the mechanical, physical and chemical requirements set forth in the current regulations on aggregates for concrete. * The workability of the concrete is not affected by the addition of the recycled fractions (coarse and/or fine), all of which show a soft consistency. * The density of the concrete with recycled aggregate is lower than that of the reference concrete in all cases, in the fresh state as well as in the hardened state. The density decreases as the proportion of recycled aggregate in the mix increases, registering density variations of less than 5% in all cases. * The entrained air content increases slightly as the amount of recycled aggregate increases, although remaining within the usual values for conventional reinforced concrete, not exceeding 1.9% in the mixes with the highest recycled aggregate content. * The compressive strength of concrete with recycled aggregate is lower than that of the reference mix, with losses of less than 13% in all cases. The greatest losses are recorded in mixes that include a higher percentage (50%) of fine recycled aggregate. * The flexural behaviour is similar to that recorded in compressive, slightly increasing the maximum loss percentage to 19%. Losses are generally greater in mixes that include a high percentage of recycled aggregate, coarse as well as fine. * All mixes are therefore suitable for use in class C30/37 structural concrete. * The expression included in the structural code for estimating the flexural strength is correct, showing values with differences of less than 10% compared to the experimental values for all mixes. * The penetration depths of water under pressure present great variability, with increases of up to 100%. However, the provisions of the regulations are complied with in all cases. The conclusions indicate that eco-concretes can be used to manufacture structural concrete analyzing mechanical performance. However, it is necessary to complement the tests carried out by analysing the durability of all mixes, as well as on full-scale structural pieces. Furthermore, in order to properly study the environmental benefit, a Life Cycle Analysis (LCA) would be necessary to estimate the environmental benefit taking into account the variables concerning waste treatment or transportation. **Author Contributions:** Conceptualization, P.P., I.F.S.d.B., J.S. and C.M. ; methodology, P.P. and I.F.S.d.B. ; software, P.P. ; validation, P.P. ; formal analysis, P.P. ; investigation, P.P. and I.F.S.d.B. ; writing--original draft preparation, P.P. ; writing--review and editing, P.P., I.F.S.d.B., J.S. and C.M. ; supervision, I.F.S.d.B., J.S. and C.M. ; project administration, J.S. and C.M. ; funding acquisition, C.M. All authors have read and agreed to the published version of the manuscript. **Funding:** This research was funded by the Spanish Ministry for Science and Innovation under project PDC2022-133285-C21 funded by MCIN / AEI/10.13039/501100011033 and, by the 'European Union NextGenerationEU/PRTR', by Spanish Ministry for Science, Innovation and Universities under project PID2022-136244 OB-I00 funded MICIU/ AEI/10.13039/501100011033 and by \"FEDER/UE\" and the IB 20131 research project financed by the Consejeria de Economia, Ciencia y Agenda Digital de la Junta de Extremadura and by the European Union Regional Development Fund (ERDF). Author [PERSON] benefitted from Spanish Ministry of Education, Culture and Sport pre-doctoral grant FPU19/06704. **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** The datasets presented in this article are not readily available because the data are part of an ongoing study. Requests to access the datasets should be directed to [EMAIL_ADDRESS].