# Evaluation of the Performance of Previous Concrete Inspired by CO\({}_{2}\)-Curing Technology
## 4 Conclusions  
The key experimental findings are listed below:  
* The pervious concrete mix developed in this study was able to infiltrate water up to 18 L/min/m\({}^{2}\) and obtained a compressive strength of about 27 MPa at the end of 28 days. This strength increased by up to 14% when the mix samples were cured in a CO\({}_{2}\)-rich environment for up to 28 days. This curing environment did not change the infiltration rate and the formation of pores in the pervious concrete;
* CO\({}_{2}\) gas easily penetrated the pervious concrete and was able to carbonate the cement components prevailing on the surface of the interconnected pore structure. This observation was evident in the cut-sample surfaces sprayed with the phenolphthalein indicator. A rich formation of calcite was observed in the microstructure of the carbonated samples;
* The passage of clay-containing bentonite water through them affected the rate of water infiltration because the pores were blocked by clay particles. This finding was observed to be the same in both the non-carbonated and carbonated samples. However, lead removal was excellent in these samples regardless of the curing conditions. Zinc removal in the carbonated and non-carbonated concrete samples reached 62% and 80% at the end of the experiment, indicating that zinc removal was outstanding when the cement matrix contained more hydroxyl sites than carbonate sites;
* Calcium release from the water passage was found to be reduced when portlandite crystals were transformed into stable carbonates due to continuous exposure to CO\({}_{2}\). Calcite solubility under running water conditions was found to be relatively lower than that of portlandite. The acid attack on the pervious concrete samples resulted in the degradation of the cement components, and only aggregates were observed to remain in the porous matrices at the end of the experiment. Their weight and strength losses reached 28% and 53%, but these losses were found to be relatively lower in the case of carbonated samples, highlighting the beneficial effect of CO\({}_{2}\) curing on the resistance to calcium leaching of pervious concrete in aggressive chemicals and urban runoff conditions. The effect of CO\({}_{2}\) curing on concrete degradation in chloride and sulfate exposure attacks will be our future study;  
Figure 10: CT, SEM, and XRD results of pervious concrete samples at the end of acid attack.  
* Prefabricated CO\({}_{2}\)-cured pervious concrete components have improved strength and durability, and the application of these environmentally friendly materials as road surfaces can effectively manage runoff and remediate environmental pollution.  
Conceptualization, methodology, validation, formal analysis, investigation, data curation, and writing--original draft preparation, M.M.; resources, supervision, writing--review and editing, L.S. All authors have read and agreed to the published version of the manuscript.  
This research was funded by Narodowa Agencja Wymiany Akademickiej (NAWA), grant number BPN/ULM/2021/1/00120.  
Not applicable.  
Data Availability Statement: Data were not used for the research described in the article.  
The authors declare no conflict of interest.