# One-Part Alkali-Activated Pastes and Mortars Prepared with Metakaolin and Biomass Ash
## 2 Experimental Program
### Preparation and Characterization of Mortars  
#### 2.3.1 Mix Proportion of Mortars  
After having analyzed the reaction kinetics of pastes, some selected K/Al molar ratios were used to prepare one-part alkali-activated mortars with the same aggregate/metakaolin weight ratio equal to 3.0 and two different w/s ratios equal to 0.65 and 0.49. Sand was used in saturated surface dry (s.s.d.) condition, which is reached when sand absorbs water in an amount of 2% with respect to its weight. Mortars were manufactured also with biomass ash heated at 700 \({}^{\circ}\)C in order to decompose carbonates and increase its reactivity (see Section 3.1). Mortars prepared with biomass ash were labeled as \"ASH_MK_X_X\" or \"ASH_MK_X_Xb\", where \"X_X\" represents the K/Al molar ratio and \"b\" represents the w/s ratio equal to 0.49, so that a mortar with K/Al = 1.5 is referred to as ASH_MK_1.5, if prepared with a w/s ratio of 0.65, or ASH_MK_1.5b, if prepared with a w/s ratio of 0.49. Mortars prepared with the heated biomass ash were labeled as \"HASH_MK_XX\" where \"XX\" represents the K/Al molar ratio.  
\begin{table}
\begin{tabular}{l c c c c c c} \hline \hline \multirow{2}{*}{**Mortar**} & **Biomass Ash** & **Heated Biomass Ash** & **Metakaolin** & **H\({}_{2}\)O** & **Sand** & \multirow{2}{*}{**w/s 1**} & **K/Al** \\  & **(g/L)** & **(g/L)** & **(g/L)** & **(g/L)** & & & \\ \hline ASH\_MK\_0.5 & 237 & - & 339 & 375 & 1018 & 0.65 & 0.50 \\ ASH\_MK\_1.0 & 377 & - & 269 & 420 & 808 & 0.65 & 1.00 \\ ASH\_MK\_1.5 & 469 & - & 223 & 450 & 670 & 0.65 & 1.50 \\ ASH\_MK\_1.5b & 527 & - & 251 & 381 & 753 & 0.49 & 1.50 \\ ASH\_MK\_2.5b & 661 & - & 189 & 417 & 567 & 0.49 & 2.50 \\ HASH\_MK\_1.0 & - & 377 & 269 & 420 & 808 & 0.65 & 1.00 \\ HASH\_MK\_1.5 & - & 469 & 223 & 450 & 670 & 0.65 & 1.50 \\ \hline \hline \end{tabular}  
* in w/s ratio, solid is the sum of biomass ash and metakaolin.  
\end{table}
Table 4: One-part alkali-activated mortars composition (g/L).  
\begin{table}
\begin{tabular}{l c c c c c c} \hline \hline \multirow{2}{*}{**Paste**} & **Biomass Ash** & **Metakaolin** & **H\({}_{2}\)O** & **KOH Pellets** & \multirow{2}{*}{**w/s 1**} & **K/Al** \\  & **(g)** & **(g)** & **(g)** & **(g)** & **(g)** & \\ \hline MK\_KOH\_1.00 & - & 1.43 & 1.08 & 0.49 & 0.56 & 1.00 \\ ASH\_H2O & 4.00 & - & 2.24 & - & 0.56 & - \\ ASH\_MK\_0.50 & 1.00 & 1.43 & 1.36 & - & 0.56 & 0.50 \\ ASH\_MK\_1.00 & 2.00 & 1.43 & 1.94 & - & 0.56 & 1.00 \\ ASH\_MK\_1.25 & 2.50 & 1.43 & 2.23 & - & 0.56 & 1.25 \\ ASH\_MK\_1.50 & 3.00 & 1.43 & 2.48 & - & 0.56 & 1.50 \\ ASH\_MK\_1.75 & 3.50 & 1.43 & 2.76 & - & 0.56 & 1.75 \\ ASH\_MK\_2.00 & 4.00 & 1.43 & 3.04 & - & 0.56 & 2.00 \\ ASH\_MK\_2.50 & 5.00 & 1.43 & 3.60 & - & 0.56 & 2.50 \\ ASH\_MK\_3.00 & 6.00 & 1.43 & 4.16 & - & 0.56 & 3.00 \\ \hline \hline \end{tabular}  
* in w/s ratio, solid is the sum of biomass ash and metakaolin.  
\end{table}
Table 3: Paste compositions for isothermal micro-calorimetry.  
Mortar batches were prepared by mixing powdered materials together, namely biomass ash, metakaolin and sand, for 2 min and then water was added and mixed for 5 min. Afterwards, mortars were poured and vibrated in cylindrical molds with 35 mm diameter and 70 mm height to perform mechanical tests.  
Mortars were cured at T = 20 \({}^{\circ}\)C and a relative humidity (RH) of 100%, ensured by covering the molds with a plastic foil, for 24 h. Then, they were demolded and cured in an oven at T = 70 \({}^{\circ}\)C for 24 h to speed up the curing process.