## 5 Results and Discussion
### Comparison of Compressive Strength  
The mechanical tests were conducted on the test specimens monthly, corresponding to 30, 60, and 120 days of exposure to wet-dry cycles. After exposure to ambient and marine conditions, the compressive strength results along with the 28-day compressive strength values are depicted below in Table 6 and Figure 7.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & Density, kg/m\({}^{3}\) & \multicolumn{2}{c}{Percentage change in weight between 28-day value and ambient conditioned samples (\%)} & Percentage change in weight between 28-day value and 28-day value and 28-day value and 28-day value and 28-day value (  
The results show that, under ambient conditions, the compressive strength of the test specimens remained comparatively stable for three months. A minimal increase of 5.75% in compressive strength is observed compared to the 28-day cured specimen, attributed to the difference between individual test specimens. However, a steady increase in the compressive strength is observed for the marine exposed samples. In the first month of exposure to seawater, the compressive strength increased by 24% compared to the 28-day cured specimen and 19% for similar specimens under ambient exposure. This shows the greater affinity of geopolymer concrete mixes towards heat treatments and favourable saline conditions for the activator content. After two months of exposure to marine conditions, the compressive strength showed a slight increase of 6%; however, after three-month exposure, the strength development remained stabilised at three months of exposure to the wet-dry cycles, which simulates harsher marine exposure. It is interesting to note that, in comparison to the ambient exposed specimens, there was a 10 MPa increment in the compressive strength of the cylinder specimens even under these harsh marine exposure conditions. This is similar to the observation by [PERSON] et al. [4], wherein the geopolymer concrete cured under humidity (90% RH) and/or water immersion reported higher compressive strengths. This can be attributed to the formation of stronger bonds by hydration of slag particles that had not yet reacted with the alkaline activator [4] while avoiding the leaching phenomenon under higher humidity conditions [4]. Again, it is reported in the literature that higher temperatures are known to favour strength increments in geopolymer concrete, which can be confirmed here. It is understood that a higher temperature offered by the 50 \(\pm\) 2 \({}^{\circ}\)C wet-dry cycles creates a heated environment that aids in the development of the strength of the core of the geopolymer concrete; thus, any unreacted species polymerises during the process. Moreover, due to the formation of \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{Days of Exposure} & \multicolumn{3}{c}{Compressive strength, MPa} & \multicolumn{2}{c}{Percentage change in weight between \multirow{2}{*}{28-day value and ambient conditioned samples (\%)}} & \multicolumn{2}{c}{Percentage change in weight between \multirow{2}{*}{28-day value and sample conditioned samples (\%)}} \\  & Value of & \multirow{2}{*}{\begin{tabular}{c} Ambient conditions \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} Marine conditions \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} weight between \\ 28-day value and \\ ambient conditioned samples (\%) \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} Percentage change in \\ weight between \\ 28-day value and \\ marine conditioned samples (\%) \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} Percentage change in \\ weight between \\ 28-day value and \\ marine conditioned samples (\%) \\ \end{tabular} } \\  & & & & & & \\ \hline
30 & & 41.7 & 49.61 & 4.25 (+) & 24.02 (+) & 18.97 (+) \\ \hline
60 & 40 & 42.5 & 52.73 & 6.25 (+) & 31.82 (+) & 24.07 (+) \\ \hline
120 & & 42.3 & 52.58 & 5.75 (+) & 31.45 (+) & 24.30 (+) \\ \hline \hline \end{tabular} Note: (+) corresponds to an increase in value.  
\end{table}