## 4 Results and Discussion
### Compressive Strength and Young's Modulus  
The compressive strength and Young's modulus values have been plotted against the BA content of TGPFs cured at a constant temperature in Figure 11. In Figure 12, compressive strength and Young's modulus are plotted against curing temperature for all of the compositions.  
It can be seen from Figure 11 that there is a general trend of increasing compressive strength and Young's modulus with increasing BA or decreasing liquid/solid ratio at all CTs, with an exception of a decrease in compressive strength and Young's modulus values at 600 \({}^{\circ}\)C as we increase BA content from 30% to 40%, which is due to irregular foaming of 40% BA composition cured at 600 \({}^{\circ}\)C; this result is in accordance with the bulk density values, as bulk density also decreases when BA content is increased from 30% to 40% at 600 \({}^{\circ}\)C CT, as mentioned earlier in 4.4. Figure 11 shows that  
Figure 10: Effect of (**a**) bottom ash content and (**b**) curing temperature on the WLI of TGPFs.  
the maximum compressive strength and Young's modulus values are presented by the TGPFs cured at 600 \({}^{\circ}\)C. The maximum Young's modulus values at the curing temperature of 600 \({}^{\circ}\)C suggests the catastrophic failure of TGPFs cured at 600 \({}^{\circ}\)C, and this effect was observed during the mechanical testing. The curves at 400 \({}^{\circ}\)C and 500 \({}^{\circ}\)C CTs shows the minimum compressive strength and Young's modulus. This behaviour is in accordance with the bulk density, WLI, and FTIR analysis results, which show the minimum degree of geopolymerization for TGPFs cured at 400 \({}^{\circ}\)C and 500 \({}^{\circ}\)C, as shown earlier in Figure 5b.  
Figure 12a shows that there is a general trend of decrease in compressive strength as CT increases from 200 \({}^{\circ}\)C to 500 \({}^{\circ}\)C, and then there is a sharp increase in the compressive strength as we move from 500 \({}^{\circ}\)C to 600 \({}^{\circ}\)C. This behaviour is due to the viscous phase transition while moving from 500 \({}^{\circ}\)C to 600 \({}^{\circ}\)C, as mentioned earlier. Figure 11b shows that the Young's modulus values decrease from 200 \({}^{\circ}\)C to 400 \({}^{\circ}\)C and then increase again up to 600 \({}^{\circ}\)C CT for all the compositions except for 40%, in which the Young's modulus decreases as the CT is increased from 500 \({}^{\circ}\)C to 600 \({}^{\circ}\)C. It is clear from Figure 11(a and b) that the minimum compressive strength and Young's modulus values are obtained by 10% and 20% BA compositions, and this effect is in accordance with the bulk density, FTIR, and WLI values, which show the minimum degree of geopolymerization for the10% and 20% compositions, as shown earlier in Figure 6. The maximum compressive strength and Young's modulus values are 7.96 MPa and 1.21 GPa, which are obtained by BA30-600.  
Figure 11: Effect of composition on the (**a**) compressive strength and (**b**) Young’s modulus of TGPFs at a constant curing temperature.  
Figure 12: Effect of curing temperature on the (**a**) compressive strength and (**b**) Young’s modulus of TGPFs of the same composition.