This paper is grounded on the following information: (1) Disposable masks primarily consist of polypropylene fiber, which exhibits excellent flexibility. (2) China has extensive coal gangue deposits that pose a significant environmental hazard. (3) Coal gangue concrete exhibits greater fragility compared to regular concrete and demonstrates reduced resistance to deformation. With the consideration of environmental conservation and resource reutilization, a preliminary concept suggests the conversion of discarded masks into fibers, which can be blended with coal gangue concrete to enhance its mechanical characteristics. In this paper, the stress–strain law of different mask fiber–doped coal gangue concrete (DMGC) under uniaxial compression is studied when the matrix strength is C20 and C30, and the effect of mask fiber content on the mechanical behavior and energy conversion relationship of coal gangue concrete is analyzed. The experimental results show that when the content of mask fiber is less than 1.5%, the strength, elastic modulus, deformation resistance, and energy dissipation of the concrete increase with mask fiber content. When the amount of mask fiber is more than 1.5%, because the tensile capacity and energy dissipation level of concrete produced by the mask fiber cannot compensate for the compression and deformation resistance of concrete of the same quantity and because excess fiber is difficult to evenly mix in the concrete, there are pore defects in concrete, which decreases the concrete strength due to the increase in mask fiber. Therefore, adding less than 1.5% mask fiber helps to improve the ductility, toughness, impermeability, and oxidation and control the cracking of coal gangue concrete. Based on Weibull theory, a constitutive model of DMGC is established, which fits well with the results of a uniaxial test, providing support for understanding the mechanical law of mask fiber–doped concrete.

Ground source heat pump systems are prone to long-term ground thermal imbalance in severe cold regions because seasonal heat extraction considerably exceeds summer heat rejection. To address this issue, this study proposes a proton exchange membrane fuel cell-assisted ground source heat pump system with cascade waste heat recovery for a heating-dominated industrial building in Changchun, Northeast China. A TRNSYS-based dynamic simulation model was developed by coupling the building load, PEMFC stack, vertical ground heat exchanger, water-source heat pump, thermal storage tank, battery storage, circulation pumps, and coordinated control modules. The recovered PEMFC waste heat was preferentially used for space heating and thermal storage and was further allocated for ground-side thermal compensation when required. Annual and ten-year simulations were conducted to evaluate the effects of PEMFC integration on ground-side temperature, soil thermal balance, heat pump power consumption, and seasonal coefficient of performance. The simulated annual heating and cooling demands were 516,721 and 99,538 kWh, respectively, confirming the strongly heating-dominated load profile of the case building. Compared with the reference GSHP system, the PEMFC-assisted system reduced the annual soil temperature drop from 1.24 °C to 0.37 °C. Over ten years, the final average soil temperature increased from 7.29 °C to 9.95 °C, corresponding to a 52.1% reduction in cumulative soil temperature decline. In addition, the winter heat pump power range decreased from 15.76–39.94 kW to 12.33–28.90 kW, while the average heating-season COP increased from 4.68 to 5.21. These results demonstrate that PEMFC waste heat recovery can serve not only as an auxiliary heating source but also as an active ground thermal compensation mechanism, thereby improving the long-term thermal sustainability and operational performance of GSHP systems in severe cold regions.