## 3 Results and Discussion
Also, the void ratio in geopolymer concrete specimens decreased as the fly ash replacement increased. However, although the void ratio decreased, the compressive strength value decreased [33]. This is because as the rate of slag, which is the main binder, decreases, the rate of CaO reaction in the geopolymer concrete also decreases. As the CaO ratio in the specimens decreases, the geopolymerization rate is reduced [35]. The aim of this study is to develop concrete that can withstand high temperatures while also being able to endure the regions and adverse climatic conditions in which it will be used. In order to assess the concrete's suitability for cold weather conditions, a freeze-thaw test was carried out. It is worth noting that the mechanical strength of concrete tends to decrease as the void ratio in its internal structure increases, which can be caused by exposure to the freeze-thaw cycle. Additionally, this may result in a reduction in the concrete's high-temperature resistance. As shown in Figure 11, the results of the freeze-thaw test indicate that all specimens, except for G100 and S100, experienced a similar percentage of weight loss. The compressive strength, ultrasonic pulse velocity (UPV), and water absorption tests suggest that the G100 and S100 specimens have high void structures, as evidenced by their high freeze-thaw weight loss and low workability. Figure 11: Weight loss as a result of freeze-thaw test (%). Figure 10: 28 th-day UPV test (km/sec) on pre-test specimens. This study employed scanning electron microscopy (SEM) to detect the micro-internal structure of CFGC. SEM and EDS scans were performed on specimens containing 2%, 5%, and 10% CFGC. Figure 12 displays the SEM scan of the ceramic fiber, while Figure 13 illustrates the percentage distribution of atoms in the ceramic fiber due to EDS analysis. Upon examining the data in Figure 13, it can be observed that the ceramic fiber is primarily composed of oxygen (O), aluminum (Al), and silicium (Si). Through the examination of this data, it is possible to compare the atomic ratios in GS90 specimens that were cast with varying ceramic fiber ratios. SEM images and EDS scans of CFGC specimens are displayed in Figures 14-19. The ceramic fibers are marked with yellow rings in the SEM images. Figure 16: SEM image of 5% CFGC. Figure 17: EDS image of 5% CFGC. Figure 18: SEM image of 10% CFGC. Figure 7:0 EDS image of 2% CFGC. Upon examination of the SEM images, it was observed that the ceramic fiber had dissolved and was evenly distributed throughout the geopolymer concrete. Specifically, the substitution of ceramic fiber in the GS90 geopolymer specimen resulted in an increased ratio of Si and Al. This can be attributed to the fact that the primary components of the ceramic fiber are composed of Si and Al. It has been observed that the fire resistance of geopolymer concrete can be improved by increasing the ratio of Si elements. Furthermore, it is possible to incorporate ceramic fiber into geopolymer concrete as a high-temperature resistant material. The objective of this study is to examine the effects of high temperatures on concrete and propose the addition of ceramic fiber to geopolymer concrete. A review of studies measuring the high-temperature behavior of concrete reveals that compressive strength is typically measured after specimens are exposed to a high-temperature oven for two hours and then returned to room temperature. In this study, the concrete specimens were cooled to room temperature by preventing moisture absorption. The oven was preheated to the desired temperature before the specimens were placed inside for testing. Following a 2-hour wait at the specified temperature, the samples were removed from the oven. The compressive strength tests were conducted at room temperature in accordance with the standards. The specimens were kept in a moisture-free environment and allowed to cool for approximately 30 minutes before being subjected to compressive strength tests.