## 3 Results and Discussion
### Environmental Characterization  
The environmental characterization through leaching tests in deionized water according EN 12457-2 was performed to assess the potential release of heavy metal(loid)s in the AA-WBA binders. In the case of the WBA, the test was carried out for both a non-milled sample and milled sample to evaluate if the process of particle size reduction increased the potential release of heavy metals and metal(loid)s on leachates. In the AA-WBA, the test was carried out on crushed particles below 4 mm, aiming to simulate the worst possible scenario for the AA-WBA leachates, which is at the end of their life cycle when they are demolished. The leaching concentrations of heavy metal(loid)s in WBA and AA-WBA binders are given in Table 5. In WBA, the leaching concentrations of Cu, Cr (only for WBA powder), Mo, and Sb exceeded the limit for acceptance at landfills for inert waste [59]. Most of the heavy metal(loid)s were more leached (As, Pb, Ni, Sb, and Zn) in AA-WBA binders when compared to WBA due to pH increase and the greater pH-dependent metals' mobility. Leaching concentration of Cu and Mo exceeded the acceptance at landfills for inert waste. However, Sb and As were the main causes of concern, since the former exceeded the limit marked for acceptance at landfills for non-hazardous waste, whilst As was very close to this limit. The presence of these two heavy metal(loid)s was because of the substantial amount of primary and secondary glass in the WBA [6]. Arsenic (As\({}_{2}\)O\({}_{3}\)) and antimony (Sb\({}_{2}\)O\({}_{3}\)) oxides are extensively used in the glass industry as fining agent, to lighten glass and to remove air bubbles [60]. It is important to highlight that the AA-WBA binders were subjected to an aggressive leaching test. The authors expect better results can be obtained with other, less aggressive leaching tests (such as the monolithic test). The environmental characterization reveals that the higher Na\({}_{2}\)O content in alkali-activator solution, the higher the heavy metal(loid)s' activation.  
Figure 10: Bulk density and compressive strength of AA-WBA binders.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline
**Sample** & **As** & **Ba** & **Cd** & **Cr** & **Cu** & **Hg** & **Mo** & **Pb** & **Ni** & **Sb** & **Zn** & **pH** \\ \hline Non-milled WBA & 0.02 & 0.42 & \textless{}0.01 & 0.21 & 3.27 & 0.05 & 0.71 & 0.07 & \textless{}0.03 & 0.23 & 0.90 & 9.66 \\ WBA powder & 0.04 & 0.37 & \textless{}0.01 & 0.51 & 3.33 & 0.01 & 1.26 & 0.03 & \textless{}0.03 & 0.35 & 0.44 & 11.33 \\ \hline AA-WBA-2M & 1.29 & 0.05 & 0.01 & 0.47 & 3.46 & \textless{}0.01 & 0.94 & 0.41 & 0.23 & 1.61 & 2.30 & 11.26 \\ AA-WBA-4M & 1.44 & 0.07 & 0.02 & 0.34 & 2.80 & \textless{}0.01 & 0.85 & 0.51 & 0.27 & 1.50 & 3.26 & 11.39 \\ AA-WBA-6M & 1.51 & 0.08 & 0.00 & 0.27 & 3.25 & 0.01 & 0.88 & 0.54 & 0.29 & 1.62 & 3.44 & 11.62 \\ A-WBA-8M & 1.65 & 0.08 & 0.00 & 0.37 & 3.91 & 0.12 & 0.89 & 0.40 & 0.12 & 1.93 & 3.09 & 11.77 \\ \hline \hline \end{tabular}  
* Inert waste (mg-kg\({}^{-1}\)) 0.5 & 20 & 0.04 & 0.5 & 2 & 0.01 & 0.5 & 0.5 & 0.4 & 0.06 & 4 \\ \({}^{1}\) Non-hazardous waste (mg-kg\({}^{-1}\)) 0.2 & 100 & 1 & 0 & 0.2 & 10 & 10 & 10 & 0.7 & 50 \\ \({}^{1}\) Hazardous waste (mg-kg\({}^{-1}\)) 0.2 & 25 & 300 & 5 & 70 & 100 & 2 & 30 & 50 & 40 & 5 & 200 \\ \hline \hline \end{tabular}  
* Limit for acceptance at landfills [59].  
\end{table}
Table 5: Leaching concentrations (mg-kg\({}^{-1}\)) on WBA and AA-WBA binders after leaching tests (EN 12457-2) and limits for acceptance at landfills.