## 3 Results and Discussion
### Effect of Foaming Agents  
To compare the effect of foaming agents (conventional foaming liquid vs. permeable foaming concentrate), both blended and GP cement mixtures were manufactured with 50% foam volume. Table 4 compares the cast densities of blended and GP cement fabricated with conventional foaming liquid and permeable foaming agents. It is deduced from this table that foaming agent types may affect the density of the foam concrete. Regardless of the mix type, foam concrete prepared with permeable foaming concentrate shows lower density than that prepared with Aerlite-IX. Blended and GP cement mixes prepared using permeable foaming concentrate achieved 6% and 2% lower density than those produced utilising Aerlite-IX, respectively. The effect of foam agent types on the density variation could be significant depending on the foam percentage in the mixes.  
Figure 6 compares the compressive strength of the blended and GP cement cube samples prepared with conventional foaming liquid and permeable foaming concentrate. As shown in this figure, irrespective of age and foam concrete mix type, samples prepared with conventional foaming liquid have significantly higher compressive strength than those made of permeable foaming concentrate as a foam concentrate. With the 3-, 7- and 28-day compressive strength, the blended mixes prepared with permeable foaming concentrate were found to be 50, 54 and 45% lower compared to the same mixes manufactured using conventional foaming agents, respectively. Similarly, the 3-, 7- and 28-day compressive strength of the GP cement mixes prepared with permeable foaming concentrate are found to be 54, 56 and 53% lower compared to the same mixes manufactured using conventional foaming agents, respectively.  
Thus, compared to the ultimate strength of a foam concrete mix prepared with a conventional foaming agent, the strength of the same mix can be compromised by more than 50% when it is produced with permeable foaming concentrate. However, both the foaming agents attained the minimum strength requirement for infill (0.5-2 MPa, as per Vic Roads Australia) application, and the use of permeable foaming concentrate can be beneficial where drainage through the foam concrete is preferred.  
Unlike ordinary concrete, the initial setting time of a foam concrete mix may vary from 6 to 7 h and the final setting time may vary between 11 and 22 h. Therefore, the setting time of the mixes was examined in this study. Both foam concrete specimens were prepared using 70% foam content to record the setting time. The 70% foam concrete was selected since it is the most common foam content utilised by the industry partner. Hence, the conventional foaming liquid concentrate was diluted with water at a ratio of 1:40 and  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Mixes**} & \multicolumn{2}{c}{**Cast Density (kg/m\({}^{3}\))**} \\ \cline{2-3}  & **Conventional Foaming Agent** & **Permeable Foaming Agent** \\ \hline Blended & 785 & 735 \\ \hline GP cement & 845 & 826 \\ \hline \hline \end{tabular}
\end{table}
Table 4: The cast densities of the mixes prepared with conventional foaming liquid and permeable foaming concentrate.  
the permeable foaming concentrate was diluted with water at 1:50 to obtain the required foam content.  
The setting time of the blended and GP cement mixes was assessed using a Vicat apparatus and listed in Table 5. The foam concrete mix prepared with the conventional foaming liquid concentrate was observed to set faster than the same mix prepared with permeable foaming concentrate.