# Testing Concrete for the Construction of Winemaking Tanks
## 3 Results and Discussion
### Chemical Properties
Additionally, the measurements meet the standards of the International Oenological Codex (IOC, Tables 9 and 10), below 1 mg/kg for Cr and below 5 mg/kg for Ni. The main interest of the leaching test of concrete is focused on the calcium leaching [35], coming from the dissolution of portlandite [36] because this component is essential for the micro-structure, the strength development and the durability of the concrete. In the present study, the total calcium hydroxide content (Table 9) is much greater than the leached quantity in mg/L found in Table 10 for calcium. R series (plain uncoated concrete) presented a lower leachability in red wine than in white wine. Adding to that, the presence of pozzolan did not influence the leachability of calcium and potassium, as both CP10 and C3 uncoated (R) had similar leaching amounts of these cations. Consequently, the present study cannot find correlations between pozzolan addition and calcium leaching reduction. \begin{table}
\begin{tabular}{l c c c c c c c c c c c} \hline  & **Units** & **White Wine** & **Limits 1** & **DK\_C3** & **DK\_CP10** & **SK\_C3** & **SK\_CP10** & **AK\_C3** & **AK\_CP10** & **RK\_C3** & **RK\_CP10** \\ \hline pH & - & 4.01 & & 4.3 & 4.33 & 6.6 & 6.51 & 6.32 & 7.09 & 6.35 & 6.3 \\ Ca & mg/L & 21.4 & & 22.3 & 23.2 & 85.6 & 81.2 & 83 & 59.3 & 87.7 & 89.3 \\ Cr & mg/L & 0.31 & & 0.31 & 0.36 & 0.40 & 0.40 & 0.36 & 0.34 & 0.39 & 0.4 \\ Cu & mg/L & 0.18 & \textless{}1.0 & 0.14 & 0.14 & 0.42 & 0.34 & 0.33 & 0.51 & 0.38 & 0.35 \\ Fe & mg/L & 1.9 & & 9.0 & 8.68 & 7.4 & 7.38 & 7.74 & 8.37 & 5.54 & 6.39 \\ K & mg/L & 314.4 & \textless{}100 & 688 & 718.4 & 754.8 & 744 & 736 & 800 & 754 & 772 \\ Mg & mg/L & 115.2 & & 119.4 & 117.8 & 144.2 & 145.4 & 143 & 135.8 & 146.8 & 145.8 \\ Mn & mg/L & 1.81 & & 1.62 & 1.79 & 1.46 & 1.54 & 3.56 & 2.7 & 1.56 & 1.52 \\ Na & mg/L & 11.2 & & 11.3 & 10 & 176.2 & 147 & 174.8 & 648 & 88 & 75.4 \\ Zn & mg/L & 0.93 & \textless{}50 & 0.89 & 1 & 0.86 & 0.68 & 0.65 & 0.9 & 0.81 & 0.69 \\ As & \(\mu\)g/L & 12.2 & & 2.4 & 2.8 & 26.4 & 27.8 & 19.6 & 19.8 & 24.8 & 24.4 \\ Cd & \(\mu\)g/L & 0.6 & & ND 2 & ND & ND & ND & ND & ND & ND \\ Co & \(\mu\)g/L & 3 & \textless{}1000 & 5.2 & 6.6 & 15.8 & 22.4 & 26.6 & 58.8 & 16.4 & 15.6 \\ Hg & \(\mu\)g/L & ND & & ND & ND & ND & ND & ND & ND & ND & ND \\ Ni & \(\mu\)g/L & 38.4 & \textless{}100 & 55.2 & 77 & 216.8 & 190 & 127.6 & 243.2 & 162.8 & 153.6 \\ Pb & \(\mu\)g/L & ND & \textless{}5000 & ND & ND & ND & ND & ND & ND & ND & ND \\ Se & \(\mu\)g/L & 0.4 & & 7.2 & 7.4 & 8.6 & 8.8 & 8 & 6.4 & 7 & 8.2 \\ \hline \end{tabular}  
* As proposed by IOC OENO 18/2003 [32]. 2 ND: not detected.  
\end{table} 
Table 10: Determination of metals and pH value of red wine, after 30 days immersion of concrete in red wine. The latter might be connected to the lower open porosity and greater density of C3 concrete, compared to CP10. But also, it should be taken into account that the utilization of pozzolan in the concrete mixture contributed to the properties before the leaching test, as the calcium hydroxide was reduced (Table 7) prior to durability tests. The modification of pH value of wine is attributed to the dissolution of hydroxyl anions into the wine, as previously explained by [PERSON] et al. [37]. Then, the pH of the wine increases. This phenomenon explains the modification of pH value on the uncoated samples (Table 8). Three of the four tested coatings presented similar behaviour, as their utilization did not prevent the pH decrease. Epoxy-based coating (D) eliminated the ion exchange and the dissolution of metals, as well as hydroxyl anions in the wine. The present effort focused on studying and comparing the mechanical properties of concrete compositions, as well as the durability and the influence of different coatings, to clarify and propose the optimum options for their use in concrete tanks for wine fermentation. The water to binder ratio of the concrete matrix, the addition of pozzolan and the acidity of the solution are key factors for the leaching behaviour of the concrete, or the coated concrete [38].