Coal gangue is a byproduct of coal mining and processing, and according to incomplete statistics, China has amassed a substantial coal gangue stockpile exceeding 2600 large mountains, which poses a serious threat to the ecological environment. Utilizing gangue as a coarse aggregate to produce gangue concrete (GC) presents a promising avenue for addressing the disposal of coal gangue; however, gangue concrete presents several challenges that need to be tackled, such as low strength and poor resistance to repeated loads. In this study, polypropylene fibers (PPFs) were incorporated into gangue concrete to enhance its utilization rate. Uniaxial compressive and repeated loading experiments were then conducted to investigate the uniaxial strength and fatigue properties of polypropylene fiber-reinforced gangue concrete (PGC) with varying gangue substitution rates (20%, 40%, and 60%) and different polypropylene fiber admixtures (0, 0.1%, 0.2%, and 0.3%). The findings indicate that incorporating gangue at a substitution rate of 40% could notably enhance the uniaxial compressive strength of PGC, resulting in a maximum increase of 19.4%. In the repeated loading experiments, the ductility of PGC was enhanced with the incorporation of PPFs, resulting in a reduction of 33.76% in the damage factor and 19.42% in residual strain for PGC-40-0.2 compared to PGC-40-0. A PPF content of 0.2% was found to be optimal for enhancing the fatigue performance of PGC. Scanning electron microscope (SEM) testing proved the improvement effect of polypropylene fiber on gangue concrete from a microscopic perspective. This study provides crucial experimental data and a theoretical foundation for the utilization of gangue concrete in complex stress environments.

As a waste derivative, glass fiber has drawn a lot of interest from the engineering community. The purpose of this study was to use glass fiber to improve the performance of defective gypsum boards. Single compression experiments, repeated loading experiments, and scanning electron microscopy (SEM) testing were performed on defective gypsum boards. The results showed that the addition of glass fiber can improve the compressive strength of defective gypsum boards. When the fiber concentration is 1.5%, the strength of single-hole gypsum boards increases by 77.1%. Energy evolution and residual strain evaluation after repeated loading showed the significant reinforcement of the dual-hole gypsum board samples with the addition of glass fiber, improving the stress distribution and elasticity, which was confirmed using damage factor analysis. Glass fibers reduce stress concentrations, improve integrity, and prevent brittle failure, especially at high stress levels. The microstructural analysis showed that the addition of glass fiber improves adhesion and prevents microcracking while acting as a stress transfer bridge, enhancing the behavior of the specimen under cyclic loading. Based on the experimental results and cost, 1.5% glass fiber is the optimal concentration. The research results provide new ideas for the application of glass fiber in defective and brittle materials and contribute toward the sustainable development of the construction industry.