## 3 Results and Discussion
### Radiological Results  
Table 5 shows the activity concentration values of \({}^{232}\)Th, \({}^{226}\)Ra, and \({}^{40}\)K. All specimens showed activity concentrations for \({}^{226}\)Ra and \({}^{232}\)Th lower than typical concentrations for concrete in the EU [59] (35 Bq/kg for \({}^{232}\)Th and 60 Bq/kg for \({}^{226}\)Ra), but values above 392 Bq/kg for \({}^{40}\)K (EU average) were achieved. Binders containing other wastes (such as titanium dioxide waste [60] or red mud [61]) present higher activity concentrations than OR (of \({}^{226}\)Ra and \({}^{232}\)Th), sin embargo when co-combustion fly ash is used [62] the activity concentrations are lower than OR but higher than egg and scallop shells. In particular, the behavior of specimens composed of biomass fly ash is noteworthy (CP-20-OR-80 and CP-92.5-OR-7.5). The component responsible for this radioactivity concentration value, which is an order of magnitude higher than the average, must be the OR incorporated into the material. During the growing process, olive pomace is naturally enriched in potassium (radioactive and stable isotopes) from fertilizers and soil. When olive pomace is used as biofuel, it has a K\({}_{2}\)O concentration of up to 22.5%, which corresponds to 5200 Bq/kg. When fly ash is \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multicolumn{6}{c}{**Leaching Limit (mg/kg, Dry Base)**} \\ \hline \multicolumn{6}{c}{**1999/31/Ec [41]**} \\ \hline Element & Hazard & Non- & Inert and & Italian & & & \\  & & & Portuguese & & & & \\  & & & limit [42] & & & & \\ \hline Zn & 200 & 50 & 4 & 0.03 & 1.1 & \(\leq\)0.03 & \(\leq\)0.03 & 0.02 \\ \hline Se & 7 & 0.5 & 0.1 & 0.1 & \(\leq\)0.1 & \(\leq\)0.1 & 0.4 \\ \hline Sb & 5 & 0.7 & 0.06 & - & \(\leq\)0.1 & \(\leq\)0.1 & \(\leq\)0.1 & 0.2 \\ \hline Pb & 50 & 10 & 0.5 & 0.5 & \(\leq\)0.1 & \(\leq\)0.1 & \(\leq\)0.1 & 9.2 \\ \hline Ni & 40 & 10 & 0.4 & 0.1 & \(\leq\)0.1 & \(\leq\)0.1 & \(\leq\)0.1 & 1.2 \\ \hline Mo & 30 & 10 & 0.5 & - & \(\leq\)0.1 & 0.2 & 0.7 & 1.7 \\ \hline Hg & 2 & 0.2 & 0.01 & 0.01 & \(\leq\)0.1 & \(<\)0.1 & \(<\)0.1 & \(<\)0.1 \\ \hline Cu & 100 & 50 & 2 & 0.5 & 0.5 & 0.1 & 0.8 & 6.5 \\ \hline Cr (total) & 70 & 10 & 0.5 & 0.5 & 0.6 & \(<\)0.2 & \(<\)0.2 & \(<\)0.2 \\ \hline Cd & 5 & 1 & 0.04 & 0.05 & \(<\)0.03 & \(<\)0.03 & \(<\)0.03 \\ \hline Ba & 300 & 100 & 20 & 10 & 0.4 & 0.9 & 1.2 & 0.3 \\ \hline As & 25 & 2 & 0.5 & 0.5 & \(\leq\)0.3 & \(\leq\)0.3 & \(\leq\)0.3 & 1.7 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Results of EN 12457-4 leachability test and limits stated in the European landfill directive and Italian regulations. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Specimens** & \({}^{40}\)**K** & \({}^{226}\)**Ra** & \({}^{232}\)**Th** \\ \hline CP-100 & 192 \(\pm\) 9 & 30.5 \(\pm\) 1.3 & 23.9 \(\pm\) 3.2 \\ \hline CP-20-E-80 & 46.4 \(\pm\) 3 & 8.2 \(\pm\) 0.5 & 5.3 \(\pm\) 0.4 \\ \hline CP-20-SC-80 & 53.3 \(\pm\) 5.6 & 7.5 \(\pm\) 0.4 & 5.1 \(\pm\) 0.5 \\ \hline CP-20-OR-80 & 3683 \(\pm\) 154 & 18.8 \(\pm\) 1.8 & 20.6 \(\pm\) 1.5 \\ \hline CP-92.5-E-7.5 & 179 \(\pm\) 9 & 27.6 \(\pm\) 1.2 & 19.2 \(\pm\) 1.2 \\ \hline CP-92.5-SC-7.5 & 176 \(\pm\) 9 & 29.8 \(\pm\) 1.2 & 20.4 \(\pm\) 1.2 \\ \hline CP-92.5-OR-7.5 & 449 \(\pm\) 19 & 27.6 \(\pm\) 1.7 & 20.6 \(\pm\) 1.7 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Activity concentrations (Bq/kg) of \({}^{40}\)K, \({}^{226}\)Ra, and \({}^{232}\)Th. Note: CP: Portland cement; SC: scallop shells; E: eggshell; OR: biomass fly ash. added to a road-base binder in an 80%wt ratio, 40K activity concentrations can be estimated to be around 4000 Bq/kg, which corresponds to the CP-20-OR-80 activity. On the contrary, construction materials containing sea and eggshells did not have either 40K or nuclides from the 238U and 232 Th series. Their activity concentrations were the lowest values found in this study, even lower than road-base binders containing only Portland cement. The potassium concentration in the shells was very low (<0.2% in Table 1).