# The Effect of Curing Conditions on Selected Properties of Recycled Aggregate Concrete
## 4 Conclusions  
Based on the obtained results the following conclusions have been formulated:  
1. Concrete mix made of CEM I turned out to be more sensitive to slump loss at the maximal content of RCA in comparison to concrete mix with blast-furnace slag cement as a binder. However, the worst influence of RCA presence on air content in concrete mix occurred when blast-furnace slag cement was used.
2. Dry conditions of hardening were perceived as more hazardous for compressive strength in the case of concretes made of both CEM I and CEM III cement.
3. Protection against drying (water evaporation) can be more sufficient for concrete with high amounts of RCA than for ordinary concrete, taking into account compressive strength and in comparison to wet conditions of curing.
4. Statistical analysis showed that the influence of RCA participation on compressive strength was less meaningful than the way of curing for two opposite conditions (wet and dry).
5. The conditions of hardening influenced the sorption of concrete, being definitely better for wet curing and with protection against drying (water evaporation) and in both cases better for CEM III than CEM I as a binder.
6. The binder intensity index \(b_{i}\) was slightly higher for CEM III than CEM I. However, the carbon dioxide emission index \(c_{i}\) was better in cases where blast-furnace slag cement was used as a binder.
7. In terms of durability, the authors of this paper propose the eco-durability index S-CO2, especially for composites with recycled aggregate. In the conducted research, more favorable values of this index were obtained for concrete with blast-furnace slag cement, but under the condition of proper curing.  
In summary, it is worth mentioning that the authors plan to develop studies, extend their objectives and conditions, and use more sophisticated methods. The paper presented in its current form provides a certain contribution, which is expected by the authors to provide some knowledge and inspire other research.  
Conceptualization (A.M.G., D.Z.); data curation (D.Z., W.A.R.); formal analysis (A.M.G., W.A.R.); investigation (D.Z., W.A.R.); methodology (A.M.G., D.Z., W.A.R.); resources (A.M.G., W.A.R.); software  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Cement Type**} & \multicolumn{2}{c}{**RCA**} & \multicolumn{6}{c}{**Curing Conditions**} \\ \cline{3-10}  & **Content** & \multicolumn{3}{c}{**Wet**} & \multicolumn{3}{c}{**Dry**} & \multicolumn{3}{c}{**PEV**} \\ \cline{3-10}  & **(\%)** & \(b_{i}\) & \(c_{i}\) & **S-CO2** & \(b_{i}\) & \(c_{i}\) & **S-CO2** & \(b_{i}\) & \(c_{i}\) & **S-CO2** \\ \hline CEM I & 0 & 7.2 & 5.5 & 0.231 & 8.4 & 6.4 & 0.172 & 8.0 & 6.0 & 0.189 \\  & 50 & 6.7 & 5.1 & 0.226 & 8.1 & 6.4 & 0.188 & 8.5 & 6.5 & 0.212 \\  & 100 & 6.7 & 5.1 & 0.201 & 8.1 & 6.2 & 0.204 & 6.9 & 5.3 & 0.249 \\ \hline CEM III * & 0 & 7.7 & 2.8 & 0.567 & 9.3 & 3.3 & 0.325 & 8.2 & 3.0 & 0.462 \\  & 50 & 7.7 & 2.8 & 0.636 & 9.3 & 3.3 & 0.293 & 9.1 & 3.3 & 0.596 \\  & 100 & 7.7 & 2.8 & 0.590 & 9.8 & 3.5 & 0.280 & 7.6 & 2.8 & 0.637 \\ \hline CEM III ** & 0 & & 3.0 & 0.526 & & 3.6 & 0.302 & & 3.2 & 0.428 \\  & 50 & & 3.0 & 0.590 & & 3.6 & 0.270 & & 3.5 & 0.553 \\  & 100 & & 3.0 & 0.547 & & 3.8 & 0.260 & & 3.0 & 0.591 \\ \hline \hline \end{tabular}  
* *–taking into account only emissions of CO2 resulting only from cement production. **–taking into account emissions of CO2 resulting from the production of cement and ground granulated blast-furnace slag.  
\end{table}
Table 7: Indexes of eco-efficiency—binder intensity, \(b_{i}\) (kg/m3/MPa) and carbon dioxide, \(c_{i}\) (kg/MPa)—and eco-durability, S-CO2 (1/(t\({}_{\text{CO2}}\)/m3-mm/h05).  
D.Z.); visualization (D.Z., W.A.R.); writing--original draft (A.M.G., D.Z., W.A.R.); writing--review & editing (A.M.G.), supervision (A.M.G.). All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
The authors declare no conflict of interest.