Geo Polymer Concrete
The innovative material known as geo polymer concrete is a kind of concrete that does not need the addition of cement. In modern times, it is used in the construction of certain buildings and structures, such as environmentally friendly railway sleepers, modular retaining walls, and sustainable buildings that employ sustainable CFRP-reinforced recycled concrete for cleaner eco-friendly construction using new and alternative materials (Paruthi et al., 2022). Researchers are currently providing an enormous amount of attention to the concept of the sustainable building by encouraging the use of GPC and FRP in the formation of beams. The alkalinity of the concrete acts as a barrier against the corrosion that might occur in the steel reinforcement (Paruthi et al., 2022). Some buildings have been able to withstand severe weather conditions as well as exposure to salts and a mix of moisture, temperature, and chlorides that lower the alkalinity of the concrete and lead to the corrosion of steel reinforcement. These factors all contribute to the degradation of the structure.
The problem of steel corrosion and the electromagnetic interaction may be solved by using bars made of fibre-reinforced polymer (FRP), which does not attract or retain magnetic fields and never corrode. In addition, since FRP bars can withstand an extremely high amount of tensile stress, they are suitable for use as structural reinforcement. It is now common practice to use fibreglass-reinforced plastic (FRP) bars rather than steel bars as the primary internal reinforcement for concrete structures (Paruthi et al., 2022). This is done in order to increase the durability and life expectancy of the structures, which is also referred to as their serviceability (). Additionally, the use of geo-polymer concrete rather than cement-based concrete has started gaining momentum, and it is now used in particular for the fabrication of concrete structures that are environmentally friendly and sustainable. Combining FRP and GPC would offer a promising technology not only in building new structures with higher durability and higher sustainability along with adequate strength and structural integrity but also in reducing the worldwide demand for Ordinary Portland Cement (OPC), thereby reducing its production and environmental impact (Paruthi et al., 2022). The advantageous characteristics of the FRP bars and the GPC, including their successful applications in the construction of various civil infrastructures, make the combination of these two materials a promising technology (Paruthi et al., 2022).
What Role Does Loading Frequency Play?
Comparison of the Effects of Tension-Compression Fatigue and Tension-Tension Fatigue
The results of the tests conducted on the groups of tension-tension and tension-compression specimens are shown in Figure 8. These tests were conducted with 5 Hz and 1 Hz loading frequencies, respectively. It is clear from looking at the figure that the existence of a compression component as part of the loading program results in a reduction in the fatigue life of the specimens. This is consistent with what () found after doing their investigation. In addition, it would seem that this impact is at its peak intensity when the max/ult ratio is between 0.5 and 0.6.
Behaviour Characterized by a Decay in Stiffness
The stiffness degradation behaviour of some of the tested coupons is displayed in Figs. 9a–c under a variety of stress ratios and frequencies. This behaviour is represented in terms of the ratio of Young’s modulus E at any number of cycles N to the initial Young’s modulus E0, and it is plotted against the ratio of a number of cycles N to the total number of cycles at failure N. The early removal of the extensometer prior to its failure is the cause of several of the charts displaying incomplete data points. It is clear from the figure that after an early period of loss of stiffness at a quick pace, the process proceeds at a rate that is far slower. This behaviour is comparable to that of 0°/90° laminates, in which the first fast stiffness deterioration is attributable to the cracking of the transverse plies, and the matrix supplies the majority of the stiffness (). This behaviour is similar to the behaviour of 0°/90° laminates. When the specimens were put through tension-compression fatigue, it was clear that the compression phase resulted in a more significant reduction in the material’s stiffness than the tension phase.
Overall, it is arguable that the reaction and failure of axially loaded masonry contained with FRP have many features comparable to those of concrete. This is because concrete and masonry are both porous materials. As a result, creating a confinement model could be able to use the previously accumulated knowledge and expertise with concrete. In the next paragraph, an effort will be made to use this model. Overall, it is arguable that the reaction and failure of axially loaded masonry confined with FRP have many features comparable to those of concrete. This is because concrete and masonry are both porous materials. As a result, creating a confinement model could be able to use the previously accumulated knowledge and expertise with concrete. In the next paragraph, an effort will be made to use this model. Similar to confined concrete, the transverse passive pressure that develops in the masonry as a reaction to the jacket forces is the foundation of the FRP contribution to the strength and deformability of confined masonry. This pressure develops as a result of the jacket forces. This pressure is not consistent, particularly in the areas around the corners of rectangular cross-sections, as a general rule, in the form of an average value for a band that is cross-sectioned and has dimensions.
Conclusion
Inferences from monotonic stress and tension coupons with various geometries that cut from GFRP filament-wound tubes with an additional fatigue curve were as follows. If a lifetime of at least one million cycles is a requirement, it is generally advised to keep the maximum-to-ultimate stress ratio of tubes of this kind to no more than roughly 0.25 (Keya et al., 2019). Although the modulus of all coupon kinds was comparable, the tensile strengths differed significantly across types. Standard longitudinal coupons fail early in filament-wound tubes with fibres oriented at an angle relative to the longitudinal axis. This is because fibres split before achieving the full tensile strength since there is a loss of continuity of certain fibres between grips. Because the coupon is becoming shorter, the bandwidth of continuous fibers between the grips is getting bigger, which means more fibers are rupturing instead of pulling out (Jariwala & Jain, 2019). For tubes with longitudinal fibres at a tiny angle, such as in this research, slightly skewed coupons, also known as parallel to fibres, showed to be highly dependable and had the same level of strength and mode of failure as CFFT bending tests (Keya et al., 2019). The fatigue life of GFRP filament-wound tubes rises in proportion to the frequency of the load that is applied. Although the existence of a compression load component in fatigue shortens the fatigue life of GFRP filament-wound tubes, this impact has a tendency to become less pronounced as the stress ratio becomes lower. When compared to coupons that break due to fibre pullout, those that fail due to fibre rupture have a lower fatigue life and a steeper curve. When subjected to tension-tension fatigue, filament-wound GFRP tubes may experience a loss of stiffness of up to 18 per cent at stress ratios of up to 0.5 and frequencies ranging from 1 to 8 hertz (Keya et al., 2019). This loss might reach as high as 30% and 45.23% in tension and compression, respectively, when it comes to tension and compression exhaustion. This loss is represented rather well by the model in a variety of different scenarios. The empirical approach that was established for fatigue life has a good match with the test results of coupons cut from GFRP filament-wound tubes. Additionally, it was used well to forecast the fatigue life of full-scale CFFTs under bending conditions (Keya et al., 2019). The method can fairly accurately predict the fatigue life of specimens that are subjected to the same frequency but a different minimum-to-maximum stress ratio R from that which was used to obtain the curve fitting parameters (Jariwala & Jain, 2019). On the other hand, the method is not as accurate when predicting the fatigue life of specimens that are subjected to the same R but a different f from that which was used to obtain the curve fitting parameters.
References
Keya, K. N., Kona, N. A., Koly, F. A., Maraz, K. M., Islam, M. N., & Khan, R. A. (2019). Natural fibre reinforced polymer composites: history, types, advantages and applications. Materials Engineering Research, 1(2), 69-85.
Jariwala, H., & Jain, P. (2019). A review of the mechanical behaviour of natural fibre-reinforced polymer composites and its applications. Journal of Reinforced Plastics and Composites, 38(10), 441-453.
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