**4. Conclusions**

This study presents an experimental study using carbonated water as kneading water and its impact on the physical-mechanical properties of a porous CBM made with NA and RMA. The main objective was to evaluate the influence of carbonated water together with whether or not subsequent curing in carbonation chamber on the mechanical properties and explain this behaviour using XRD, SEM, and TGA/DTA. The characterisation of the mix composition with different aggregates (NA or RMA), normal water or carbonated water as kneading water, and different hardening environments (different level of CO2) were performed at 1, 3, and 7 d. The following conclusions were obtained:


The utilization of carbonated water as kneading water in CBM with recycled aggregates (circular economy) can be a novel and interesting procedure to obtain a more environmentally friendly building material without the use of a carbonation chamber. At the same time, it improves mechanical properties and contributes to climate change mitigation.

**Author Contributions:** Conceptualization, D.S.-M. and J.M.F.-R.; Methodology, J.R.J.; writing original draft preparation, D.S.-M.; writing—review and editing, J.M.F.-R. and J.R.J.; supervision, J.M.F.-R.; project administration, J.M.F.-R. and J.R.J. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by Andalusian regional government UCO-FEDER 20 research project (Ref. 1381172-R) and the Ministry of Science and Innovation of the Government of Spain through the PRECAST-CO2 research project (Ref. PID2019-111029RB-I00).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** D. Suescum-Morales acknowledges funding from MECD-Spain (http://www. mecd.gob.es/educacion-mecd/) FPU 17/04329. D. Suescum-Morales also want to thank Cesar Javier Ramos and Maria Esther Jiménez for their help in measuring the initial CO2 concentration of normal and carbonated water.

**Conflicts of Interest:** The authors declare no conflict of interest.
