## 3 Results and Discussion
### Fire Resistance  
Resistance of geopolymers to fire has become one of the crucial research areas in the current development. The inherent thermal resistance of some geopolymers makes them useful in a range of high temperature applications. Geopolymers, with PVA fibers, showed enhanced resistance to spalling at an elevated temperature, due to greater mechanical strength. It was observed that strength decreased in all the geopolymer specimens at different temperatures, and the maximum strength degradation was found in the GP0 specimen (Figure 7A). It was further noticed that resistance to an elevated temperature of geopolymer specimens increased with the increase of fiber ratio. Fiber ratio noticeably affected the resistance to high temperature. The increase in resistance of geopolymer concrete to an elevated temperature, with increasing fiber ratio, has also been reported previously [35]. The GP3, GP5, and GP7 specimens experienced a loss of compressive strength by 62.8%, 60.3%, and 58.6%, respectively, when exposed to 600 \({}^{\circ}\)C. When the temperature was further increased to 800 C, it was observed that the loss in strength of the GP3, GP5, and GP7 specimens was about 64%, whereas in the GP0 specimen it was 95.2%. The better fire resistance of GP3, GP5, and GP7 specimens at 400 \({}^{\circ}\)C and 600 \({}^{\circ}\)C might be due to the melting of PVA fibers, which formed the channels for steam to escape. [PERSON] et al. [38] also found that PVA fibers avert explosive spalling of specimens due to the provision of extra paths for vaporized moisture to escape, without generating high internal pressure in the material. The compressive strength of all the geopolymer specimens, except GP0, was found to be the same under exposure to fire at 800 \({}^{\circ}\)C. This could be due to the vanishing of PVA fiber properties at that temperature. Similar findings were observed for PVA fiber reinforced geopolymers [35]. Elevated temperature increased the porosity by producing voids, which reduced the contact area between particles, with consequent degradation of specimens [39; 40]. The reduction in compressive strength of the GP5 specimen was 29.7% lower than that of GP0, at 400 \({}^{\circ}\)C. Additionally, the reduction in the compressive strength of the GP5 specimen at 600 \({}^{\circ}\)C and 800 \({}^{\circ}\)C was 22.3% and 32.2%, respectively; lower in relation to the GP0 specimen. Pore size and pore distribution could be responsible for the retention of strength in the fly ash-based geopolymers. The geopolymer specimens which showed the best strength in the 400 \({}^{\circ}\)C and 600 \({}^{\circ}\)C temperature range, corresponding to the swelling of a silica-rich phase present as pockets within the gel structure. Specimens in which this phase was not present displayed low strength. Additionally, geopolymer composites may comprise quartz, mullite, iron oxide, and the alkali activated gel, hence, this complex microstructure offers the ability for the material to withstand extreme environmental conditions, such as high temperatures. Figure 7: Exposure of geopolymer specimens at different temperatures: (**A**) % change in compressive strength; (**B**) % weight loss. The loss in weight of the specimens during exposure to fire is shown in Figure 7B. The most pronounced weight loss (8.52%) was determined in the GP0 specimen at 800 \({}^{\circ}\)C. The GP3, GP5, and GP7 specimens lost their weight by 8.1%, 7.21%, and 7%, respectively, at 800 \({}^{\circ}\)C. The higher weight loss in the GP0 specimen is mainly due to the higher rate of evaporation of trapped moisture in the matrix, as compared to the other specimens with PVA fibers. In this research, the weight loss was measured in the range of about 5-9% for all the specimens at desired temperatures. In another work, the weight loss was recorded in the range of 5-12%, when the temperature was raised to 1000 \({}^{\circ}\)C for geopolymer specimens [17].