Mechanical properties and damage evolution of graphene oxide enhanced coal-based solid waste grouting materials

Abstract

Improving the strength and toughness of fractured coal bodies during pressure relief in impact rock roadway drilling, a reinforced and toughened grouting material (PCGN) was developed using cement (P), coal gangue (CG), graphene oxide (GO), and nanosilica (NS) as raw materials. The stability and mechanical properties of PCGN were investigated through flowability experiments, water separation rate experiments, and uniaxial compressive strength (σ_c) and tensile strength (σ_t) experiments. The phase, microstructure, and pore characteristics of PCGN were analyzed via X-ray diffraction (XRD) and scanning electron microscopy (SEM). Finally, the brittleness coefficient (BE) and static toughness (η) were used to evaluate the toughness of PCGN, and based on acoustic emission (AE) and digital speckle pattern (DIC) monitoring data, the fracture mechanism and crack propagation law of PCGN were studied. The results revealed the following. 1) The σ_c and σ_t of PCGN first increased but then decreased with increasing GO content, reaching their maximum values at 0.06 %. GO promoted the cement hydration reaction and reduced the porosity of PCGN. 2) CG and NS weakened the brittleness of the PCGN, and the BE first decreased and then increased with increasing CG and NS mass fractions. 3) The fracture mechanism of PCGN varied greatly at different levels of brittleness. As the BE decreases, the fracture mode of PCGN gradually evolves from large-scale multicrack splitting failure to small-scale uniform single crack shear failure.