## 4 Conclusions  
Coal gauge is a byproduct of coal mining and processing, and consists of a complex mixture of sandstone and shale, constituting approximately 10-25% of the total coal pro  
Figure 12: Damage constitutive model and test results fitting curve. (**a**) OC-30-0.1; (**b**) PC-30-0.1; (**c**) BC-30-0.1; (**d**) HBPRGC-30-0.1; (**e**) HBPRGC-30-0.2. Figure 13: Damage evolution characteristics of HBPRGC. (**a**) C20; (**b**) C30. duction in China. Utilizing coal gangue as an aggregate in the production of coal-gangue concrete offers an effective avenue for coal-gangue recycling and holds substantial implications for the efforts of the construction industry to reduce carbon emissions. However, compared with ordinary concrete, coal-gangue concrete has lower strength but higher brittleness. In order to enhance the strength and deformability of coal-gangue concrete, this paper has tried to add basalt fibre, polypropylene fibre, and hybrid basalt-polypropylene fibre to coal-gangue concrete, and experimentally analysed the uniaxial compressive strength, ductility, total strain energy, and dissipated energy in coal-gangue concrete after the addition of fibre with volume contents of 0.1% and 0.2%. Based on our studies, the following conclusions are derived:  
1. Basalt fibre (BF) and polypropylene fibre (PF) enhance the ductile deformation of coal-gangue concrete, with the most pronounced effect observed when both fibres are combined. At a 0.1% fibre volume content, the addition of fibres will well improve the ductile deformation of coal-gangue concrete. When the hybrid-fibre volume content is increased to 0.2%, the ductile deformation of gangue concrete increases but the elastic modulus decreases. Excessive mixing of BF and PF reduces both the compressive strength and elastic modulus of coal-gangue concrete;
2. Both BF and PF reduce the elastic strain energy-release rate of coal-gangue concrete and increase the dissipation energy. Compared to standard coal-gangue concrete, BC-20-0.1 and BC-30-0.1 display increases in total strain energy of 26.12% and 27.44%, respectively, with corresponding increases in dissipative energy of 28.15% and 23.01%, respectively. Similarly, PC-20-0.1 and PC-30-0.1 exhibit amplified total strain energy of 26.34% and 31.85%, respectively, along with corresponding increases in dissipative energy of 48.61% and 52.16%. However, HBPRGC-20-0.1 and HBPRGC-30-0.1 have elevations of 53.66% and 51.45% in total strain energy and 54.11% and 50% in dissipative energy, respectively. Thus, the combined use of BF and PF amplifies their effect on extending and toughening coal-gangue concrete;
3. For the increase in both the total strain energy and the dissipative energy in the uniaxial compression process of coal-gangue concrete, 0.1% also seems to be the optimum hybrid-fibre volume content. When the volume content of hybrid fibres reaches 0.2%, it is relatively modest when it comes to the rate of increase in both the total strain energy and the dissipative energy in coal-gangue concrete during the initial deformation stage. In the final deformation stage, relative to standard co-gangue concrete, HBPRGC-20-0.2 and HBPRGC-30-0.2 exhibit substantial increases of 42.16% and 44.87% in total strain energy, along with increases of 42.14% and 43.19% in dissipative energy, surpassing both the base group coal-gangue concrete and single-fibre gangue concrete. During the whole stress-strain process, HBPRGC-20-0.2 and HBPRGC-30-0.2 have elevations of 31.95% and 30.32% in total strain energy, and -3.46% and 28.71% in dissipative energy, respectively. These values are second to coal-gangue concrete with a mixed fibre volume of 0.1%;
4. The increased stiffness and improved bonding properties between the BF and the concrete matrix significantly contribute to the material strength. Moreover, the good ductility of PF helps restrict the expansion and penetration of macroscopic cracks. The synergistic effects of these two fibres enhance the overall ductility and toughness of the concrete;
5.