Foamed Concrete Sealing Materials for Coal Seam Gas Drainage Boreholes: A Review

ABSTRACT

Due to its low density, good pumpability, and adjustable pore structure, foam concrete shows significant potential for sealing coalbed methane extraction boreholes. However, synergistically optimizing sealing performance, gas permeability, and durability under complex geological conditions remains challenging. This review systematically examines recent progress in foam concrete sealing materials. We analyze borehole sealing failure mechanisms, gas leakage pathway evolution, and foam concrete's role in fracture filling and wall support. The paper evaluates key foaming systems and modification strategies (including physical/chemical foaming), surfactant blending, and nanoparticle reinforcement highlighting their effects on foam stability and pore connectivity. Additionally, we summarize how cementitious systems, mineral admixtures, and fibers influence matrix density, mechanical properties, and durability. While foamed concrete holds promise for balancing air leakage control and pore‐peripheral stability, critical gaps remain in quantitative pore design and long‐term performance evaluation. Future research should prioritize enhancing foaming stability, controlling matrix microstructure, improving interfacial bonding, and utilizing low‐carbon resources to guide the formulation optimization and large‐scale engineering application of foam concrete sealing materials. Future research must transcend mere material performance optimization. By enhancing foaming stability, controlling matrix microstructure, and improving interfacial bonding, the ultimate goal is to fundamentally improve gas drainage efficiency, prevent dangerous air leakage, ensure long‐term borehole stability, and provide a robust material foundation for comprehensive mine hazard mitigation.