## 3 Results and Discussion
### Physical Characteristics: Slump Flow, Flow Time, Flow Velocity and Density
In the case of the ternary mixes, however, the mixes with activator type 2 have a slightly higher slump flow value due to the presence of round fly ash combined with the lower colloidal formation of the low-silica-based activator type 2. An increase in the MWCNT content induces a higher solid ratio. Moreover, the agglomeration and high water affinity of MWCNT particles are also essential contributing factors. There was about a 4-5% decrease in the slump flow (or workability) for an increase in MWCNT content from 0.3% to 0.6% for the AAECs. Such a decrease in workability with the proportional increase in the MWCNT additive was reported in earlier studies [78]. During the slump flow diameter measurement, the flow time (T\({}_{50}\)) was recorded for the AAECs to spread up to a 500 mm diameter--a lesser T\({}_{50}\) time suggests good flowability, as per EFNARC [77]. As per Table 3, the AAEC mixes achieved T\({}_{50}\) values within a time range from 2 s to 5 s, which is considered to satisfy the criteria for good-flowability concrete [77]. A minimum slump flow time of 2 s was observed for the AAEC mix T2R6 (with activator type 2 and 0.6% rGO), whereas a maximum flow time of 5 s was observed for the binary mixes with MWCNT and MgO (Table 3). As for the control mixes, the binary variants took more time to reach a 500 mm diameter than the ternary ones. This corresponded to their lower slump velocity compared to the ternary ones (about 26% and 46% less for binary mixes with activator type 1 and 2, respectively), due to the absence of smooth round fly ash F particles that can reduce interparticle friction, which is described as being connected to the slump flow. The reduction in slump velocity is more pronounced with the use of activator type 2 due to the presence of more colloidal particles compared to type 1. The addition of 5% MgO increased the amount of finer particles with a high water affinity and thus reduced the slump velocity by about 19-20% compared to the control mixes (Table 4). Similarly, the addition of MWCNTs/rGO and increase in their content caused a reduction in the slump velocity due to inducing a  
Figure 5: Influence of (**a**) MWCNT, (**b**) rGO, and (**c**) MgO contents on slump flow characteristics. higher solid ratio in the mixes. Moreover, the agglomeration and high water affinity of the MWCNT particles were also important factors. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline
**AAEC** & \multicolumn{4}{c}{**Compressive Strength (MPa) \({}^{\star}\)**} & \multicolumn{4}{c}{**Strength Change with Respect to Control (\%)**} \\ \cline{2-10}
**Mix** & \multicolumn{4}{c}{**(+ve: Increase, –ve: Decrease)**} \\ \cline{2-10}
**ID** & **7 Days** & **14 Days** & **28 Days** & **56 Days** & **180 Days** & **7 Days** & **14 Days** & **28 Days** & **56 Days** & **180 Days** \\ \hline \multicolumn{10}{c}{Control AAECs} \\ \hline B1 & 14.3 & 28.5 & 38.5 & 45.8 & 50.3 & 0 & 0 & 0 & 0 & 0 \\ \hline B2 & 15.6 & 30.8 & 40.8 & 48.1 & 52.6 & 0 & 0 & 0 & 0 & 0 \\ \hline T1 & 14.9 & 22.5 & 30.5 & 37.8 & 42.3 & 0 & 0 & 0 & 0 & 0 \\ \hline T2 & 15 & 25.4 & 33.4 & 40.7 & 45.2 & 0 & 0 & 0 & 0 & 0 \\ \hline \multicolumn{10}{c}{5\% MgO Incorporated AAECs} \\ \hline B1M5 & 20.1 & 35.5 & 46.2 & 52.6 & 56.8 & 40.4 & 24.6 & 20 & 14.8 & 12.9 \\ \hline B2M5 & 21.4 & 37.8 & 48.5 & 54.9 & 59.1 & 37.1 & 22.7 & 18.9 & 14.1 & 12.4 \\ \hline T1M5 & 20.7 & 29.5 & 38.2 & 44.6 & 48.8 & 38.9 & 31.1 & 25.2 & 18 & 15.4 \\ \hline T2M5 & 20.7 & 32.4 & 41.1 & 47.5 & 51.7 & 38.6 & 27.6 & 23.1 & 16.7 & 14.4 \\ \hline \multicolumn{10}{c}{MWCNT (0.3\% and 0.6\%) incorporated AAEC} \\ \hline B1C3 & 17.9 & 30.5 & 41.5 & 49.4 & 53.9 & 25.1 & 7 & 7.8 & 7.8 & 7.1 \\ \hline B2C3 & 19.4 & 34.6 & 44.6 & 51.9 & 56.4 & 24 & 12.2 & 9.2 & 7.8 & 7.1 \\ \hline T1C3 & 18.4  
As can be seen, the flowability of all geopolymer binders increases with the increase in the Na\({}_{2}\)O/SiO\({}_{2}\) ratio [60; 61]. This also means that a higher alkalinity provides a higher flowability of the mixtures.