# Structural Concrete from 100% Recycled Aggregates
## 3 Concrete Mixtures
Therefore, concrete from the specimens was crushed manually into powder and then mixed with milliQ Ultra-pure water to obtain a 50% + 50% water + concrete mixture that was gently shaken for 30 min. The pH was measured by means of a Hanna PH210 PH-meter (error \(\pm\) 0.005), repeating the measurement three times. Values in Table 6 represent the average values of the three measurements. The pH of 100% RAC turns out to be around 12 (Table 6), which is much lower than the expected values for standard concrete, that is, between 13.5 and 14 for fresh concrete [38; 39]. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Days**} & \multirow{2}{*}{**4**} & \multicolumn{8}{c}{**Recycled Aggregate: Concrete**} \\  & & & \multicolumn{2}{c}{**14**} & \multicolumn{2}{c}{**28**} & \multicolumn{2}{c}{**60**} & \multicolumn{2}{c}{**90**} \\ \hline \multirow{2}{*}{\(R_{cube}\)} & 17.32 & \multirow{2}{*}{17.65} & 20.94 & \multirow{2}{*}{20.59} & 24.39 & \multirow{2}{*}{24.13} & 25.88 & \multirow{2}{*}{26.25} & 28.25 & 28.04 & 29.30 & \multirow{2}{*}{28.97} & 28.99 \\  & 17.98 & & 20.94 & & & & & & & & & \\ \hline \multirow{2}{*}{\(f_{cyl}\)} & 12.06 & \multirow{2}{*}{11.81} & 14.66 & \multirow{2}{*}{14.80} & 18.67 & \multirow{2}{*}{18.65} & 21.02 & \multirow{2}{*}{21.32} & 22.95 & \multirow{2}{*}{23.08} & 23.91 & \multirow{2}{*}{23.89} \\  & 11.56 & & 14.94 & & & & & & & & & \\ \hline \multirow{2}{*}{**Days**} & \multirow{2}{*}{**4**} & \multicolumn{8}{c}{**7**} & \multicolumn{8}{c}{**14**} & \multicolumn{8}{c}{**28**} & \multicolumn{2}{c}{**60**} & \multicolumn{2}{c}{**90**} \\ \hline \multirow{2}{*}{\(R_{cube}\)} & 9.96 & \multirow{2}{*}{9.52} & 12.83 & \multirow{2}{*}{12.22} & 15.86 & \multirow{2}{*}{15.70} & 18.76 & \multirow{2}{*}{18.49} & 19.85 & \multirow{2}{*}{19.97} & 20.25 & \multirow{2}{*}{20.41} \\  & 9.08 & & 12.22 & & & & & & & & & \\ \hline \multirow{2}{*}{\(f_{cyl}\)} & 6.72 & \multirow{2}{*}{6.54} & 9.15 & \multirow{2}{*}{8.95} & 10.80 & \multirow{2}{*}{11.17} & 12.53 & \multirow{2}{*}{12.45} & 13.45 & \multirow{2}{*}{13.30} & 13.66 & \multirow{2}{*}{13.38} & 13.78 \\  & 6.36 & & 8.75 & & & & & & & & & \\ \hline \multirow{2}{*}{**Days**} & \multirow{2}{*}{**4**} & \multicolumn{8}{c}{**7**} & \multicolumn{8}{c}{**14**} & \multicolumn{8}{c}{**28**} & \multicolumn{2}{c}{**60**} & \multicolumn{2}{c}{**90**} \\ \hline \multirow{2}{*}{\(R_{cube}\)} & 16.95 & \multirow{2}{*}{17.09} & 19.87 & \multirow{2}{*}{19.35} & 21.80 & \multirow{2}{*}{22.36} & 24.41 & \multirow{2}{*}{23.95} & 24.18 & 26.28 & 26.94 & \multirow{2}{*}{26.12} & 26.94 & \multirow{2}{*}{26.65} \\  & 16.50 & & 18.82 & & & & & & & & & & & \\ \hline \multirow{2}{*}{\(f_{cyl}\)} & 16.23 & \multirow{2}{*}{13.82} & 16.50 & \multirow{2}{*}{16.37} & 16.37 & 16.50 & \multirow{2}{*}{19.43} & 21.09 & \multirow{2}{*}{21.62} & 23.23 & 23.04 & 23.14 & 24.09 & \multirow{2}{*}{23.99} \\  & 16.50 & & 16.23 & & & & & & & & & & & \\ \hline \multirow{2}{*}{\(R_{cube}\)} & \multirow{2}{*}{**4**} & \multicolumn{8}{c}{**7**} & \multicolumn{8}{c}{**14**} & \multicolumn{8}{c}{**28**} & \multicolumn{2}{c}{**60**} & \multicolumn{2}{c}{**90**} \\ \hline \multirow{2}{*}{\(R_{cube}\)} & 10.56 & \multirow{2}{*}{10.73} & 13.03 & \multirow{2}{*}{13.32} & 13.18 & 16.76 & \multirow{2}{*}{16.37} & 18.45 & \multirow{2}{*}{18.37} & 20.23 & \multirow{2}{*}{20.42} & 21.17 & \multirow{2}{*}{21.22} \\  & 10.90 & & 13.32 & & & & & & & & & & & \\ \hline \multirow{2}{*}{\(f_{cyl}\)} & 7.98 & \multirow{2}{*}{7.87} & 9.68 & \multirow{2}{*}{9.60} & 11.66 & \multirow{2}{*}{11.78} & 13.52 & \multirow{2}{*}{13.60} & 15.55 & \multirow{2}{*}{15.64} & 16.06 & \multirow{2}{*}{16.10} \\  & 7.76 & & 9.52 & & & & & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Strength development in time for 100% recycled aggregate concrete. Large numbers are the average of the test data (smaller numbers).