## 3 Result and Discussion
### Effect of LDPE particles on Compressive Strength  
The effect of the fraction of LDPE particles on compressive strength is presented in Tables 2 and 3. MC and MK formed with no LDPE addition was used as a control. Geopolymer ceramic samples were cured at 30 \({}^{\circ}\)C and 50 \({}^{\circ}\)C. Clay and LDPE powder mixture was derived from the control sample, as calculated in Equation (1)  
\[\Delta\sigma=\sigma^{o}-\sigma^{o\alpha} \tag{3}\]  
where  
\(\Delta\sigma\) is a measure of the effect of LDPE addition to compressive strength  
\(\sigma^{o}\) is Compressive strength of geopolymer/LDPE composite  
\(\sigma^{o\alpha}\) is Compressive strength of geopolymer or control sample  
From Table 2, the compressive strengths were generally higher with the addition of LDPE particles to metaclay (MC). For composites formed with 0.6 mm-sized LDPE particles (95 MCGC) and cured at 30 \({}^{\circ}\)C, the variation in compressive strength was 5.65 MPa higher than the control. Similarly, strength improvement was observed for geopolymers cured at 50 \({}^{\circ}\)C. This was the highest strength increase observed as compared to the strength increase observed for the 10% and 15% LDPE addition cured at 30 \({}^{\circ}\)C. Composites formed with 5% of 0.6 mm-sized LDPE addition and cured at 50 \({}^{\circ}\)C. Five percentage LDPE addition increased the compressive strength of the ceramics to 5.81 MPa. In both composites formed at 30 \({}^{\circ}\)C and 50 \({}^{\circ}\)C, the highest gains in LDPE/geopolymer composite strength were observed for the 5% LDPE addition. The addition of 1.18 mm-sized LDPE also increased the compressive strength of the ceramics. Similar high gains in compressive strength made for the 5% 0.6 mm LDPE particles were observed for the 5% LDPE/geopolymer composites formed with the 1.18-mm-sized LDPE particles. The trend in the gains in the variation in compressive strength observed for the metacakalay (Table 2) was similar to that of metakaolin (Table 3). The addition of LDPE particles to metakaolin slightly increased the compressive strength. Powder with 0.6 mm particle size and 5% LDPE contents had gains in compressive strength variation of 4.26 MPa and 2.47 MPa for geopolymer/LDPE composites cured at temperatures 30 \({}^{\circ}\)C and 50 \({}^{\circ}\)C, respectively. Analogous results were observed for composites formed with 5% LDPE fraction and 1.18 mm LDPE powder particle size. In summary, the data presented so far showed that the inclusion of LDPE particles in the geopolymer composites slightly \begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{2}{c}{**Variation in CS (MPa) at 0.6 mm**} & \multicolumn{2}{c}{**Variation CS (MPa) at 1.18 mm**} \\ \cline{2-5}  & \(\Delta\sigma\) **at 30 \({}^{\circ}\)C** & \(\Delta\sigma\) **at 50 \({}^{\circ}\)C** & \(\Delta\sigma\) **at 30 \({}^{\circ}\)C** & \(\Delta\sigma\) **at 50 \({}^{\circ}\)C** \\ \hline
100 MCGC & 0.00 & 0.00 & 0.00 & 0.00 \\
95 MCGC & 5.65 & 5.81 & 2.68 & 1.86 \\
90 MCGC & 3.29 & 3.12 & 2.08 & 0.76 \\
85 MCGC & 2.97 & 1.82 & 0.90 & 0.54 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Effect of LDPE/MC geopolymer composite on compressive strength for composites formed using 0.6 mm and 1.18 mm LDPE particle size. \begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{2}{c}{**Variation in CS (MPa) at 0.6 mm**} & \multicolumn{2}{c}{**Variation CS (MPa) at 1.18 mm**} \\ \cline{2-5}  & \(\Delta\sigma\) **at 30 \({}^{\circ}\)C** & \(\Delta\sigma\) **at 50 \({}^{\circ}\)C** & \(\Delta\sigma\) **at 30 \({}^{\circ}\)C** & \(\Delta\sigma\) **at 50 \({}^{\circ}\)C** \\ \hline
100 MKGC & 0.00 & 0.00 & 0.00 & 0.00 \\
95 MKGC & 4.26 & 2.47 & 4.51 & 1.81 \\
90 MKGC & 3.33 & 1.17 & 3.21 & 0.85 \\
85 MKGC & 2.27 & 0.99 & 1.37 & 0.11 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Effect of LDPE/MK geopolymer matrix ratio on compressive strength. improved the compressive strength of the geopolymer ceramics.