## 2 Methodology
Notes: Q—quartz, SiO\({}_{2}\) (77–1070); CH—calcium hydroxide, Ca(OH)\({}_{2}\) (84–1271); CC—calcium carbonate, CaCO\({}_{3}\) (72–1652); A—anorthoclase, (Na,K)(Si\({}_{3}\)Al)O\({}_{8}\) (75–1631); G—gehlenite, Ca\({}_{2}\) Al(AlSiO\({}_{7}\)) (79–2421); CO—calcium oxide, CaO (4–777); MO—magnesium oxide, MgO (78–430); C—bassanite, CaSO\({}_{4}\)\(\cdot\)0.5H\({}_{2}\)O (33–310); B—brushite, CaPO\({}_{3}\)(OH)\(\cdot\)2H\({}_{2}\)O (11–293). Paste samples size was \(20\times 20\times 20\) mm; their composition is given in Table 2. The BBA was substituted for PG at various amounts: 5%, 10%, 15%, 20% and 25%. The ratio of water and solid materials (BBA + PG) in the mixtures was regulated and ranged from 0.23 to 0.30. First, dry components were thoroughly mixed. Then, the mixtures were filled with the solutions of alkali activator (Table 2). These solutions were prepared by dissolving NaOH in water. When the complex alkali activator was used WG solution was filled to sodium hydroxide solution. The total hydration duration was 28 days. The first day samples hydrated in room temperature, the second day at 60 \({}^{\circ}\)C temperature--and for the remaining 26 days, in room temperature again. All this time samples were covered with polyethylene covering materials which protect the samples from dehydration. The sand from Kvesai quarry (Lithuania) was used as fine aggregate to produce alkali activated concrete samples the 0/4 fraction sand. The particle density of sand was 2.65 Mg/m\({}^{3}\). The amount of initial materials for concrete samples is shown in Table 3.  
The compressive strength of hardened AAM paste was evaluated after 7 and after 28 days. To perform the test a hydraulic press ToniTechnik 2020 was used. The compressive strength of samples \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Samples** & **BBA, g** & **PG, g** & **WG, g** & **H\({}_{2}\)O, g** & **NaOH, g** & **SiO\({}_{2}\)/Al\({}_{2}\)O\({}_{3}\)** & **SiO\({}_{2}\)/Na\({}_{2}\)O** \\ \hline PG 0-2 & 100 & 0 & – & 23 & 20.1 & 12.0 & 2 \\ PG 5-2 & 95 & 5 & – & 28 & 19.9 & 12.0 & 2 \\ PG 10-2 & 90 & 10 & – & 29 & 18.8 & 12.0 & 2 \\ PG 15-2 & 85 & 15 & – & 30 & 17.8 & 12.0 & 2 \\ PG 20-2 & 80 & 20 & – & 30 & 16.7 & 12.0 & 2 \\ PG 25-2 & 75 & 25 & – & 30 & 15.7 & 12.0 & 2 \\ PGWG 0-2 & 100 & 0 & 20.0 & 23 & 24.5 & 14.8 & 2 \\ PGWG 5-2 & 95 & 5 & 15.8 & 28 & 22.6 & 14.3 & 2 \\ PGWG 10-2 & 90 & 10 & 14.0 & 29 & 21.2 & 14.2 & 2 \\ PGWG 15-2 & 85 & 15 & 15.7 & 30 & 20.5 & 14.6 & 2 \\ PGWG 20-2 & 80 & 20 & 16.5 & 30 & 19.7 & 14.9 & 2 \\ PGWG 25-2 & 75 & 25 & 19.5 & 30 & 19.4 & 15.6 & 2 \\ PG 0-3 & 100 & 0 & – & 23 & 13.0 & 12.0 & 3 \\ PG 5-3 & 95 & 5 & – & 29 & 12.4 & 12.0 & 3 \\ PG 10-3 & 90 & 10 & – & 30 & 11.7 & 12.0 & 3 \\ PG 15-3 & 85 & 15 & – & 30 & 11.1 & 12.0 & 3 \\ PG 20-3 & 80 & 20 & – & 30 & 10.4 & 12.0 & 3 \\ PG 25-3 & 75 & 25 & – & 30 & 9.8 & 12.0 & 3 \\ PGWG 0-3 & 100 & 0 & 6.4 & 23 & 13.0 & 13.3 & 3 \\ PGWG 5-3 & 95 & 5 & 7.1 & 27 & 12.4 & 13.5 & 3 \\ PGWG 10-3 & 90 & 10 & 6.0 & 28 & 11.7 & 13.3 & 3 \\ PGWG 15-3 & 85 & 15 & 7.3 & 30 & 11.1 & 13.7 & 3 \\ PGWG 20-3 & 80 & 20 & 7.6 & 30 & 10.4 & 13.9 & 3 \\ PGWG 25-3 & 75 & 25 & 9.7 & 30 & 9.8 & 18.4 & 3 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The mixing composition of alkali activated biomass bottom ash pastes. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Ingrediients**} & \multicolumn{4}{c}{**The Activation with NaOH**} & \multicolumn{4}{c}{**The Activation with NaOH + Na\({}_{2}\)OnSiO\({}_{2}\)-mH\({}_{2}\)O**} \\ \cline{2-7}  & **CPG 0-3** & **CPG 15-3** & **CPG 20-3** & **CPWG 0-3** & **CPWG 15-3** & **CPWG 20-3** \\ \hline BBA & 450 & 383 & 360 & 450 & 383 & 360 \\ PG & 0 & 67.5 & 90 & 0 & 67.5 & 90 \\ Sand 0/4 & 1350 & 1350 & 1350 & 1350 & 1350 & 1350 \\ NaOH & 58.5 & 49.7 & 46.8 & 58.5 & 49.7 & 46.8 \\ Water glass & 0 & 0 & 0 & 28.8 & 32.9 & 34.2 \\ Water & 210 & 210 & 210 & 200 & 200 & 200 \\ \hline \hline \end{tabular}
\end{table}