Study on viscosity time-varying law and microscopic chain forming mechanism of Fe3O4 magnetic slurry

Complex and changeable engineering geological conditions pose major challenges to underwater construction. Slurry grouting under dynamic water conditions is difficult to regulate in real time, resulting in slurry loss and a low retention rate. This study develops a new type of magnetic grouting material based on materials science and electromagnetism, and examines the characteristics of slurry with different magnetic powder dosages. The relationship between shear stress and magnetic field strength was investigated using a rheological test. The magnetisation rate ( χ ) of the material was measured using a vibrating sample magnetometer (VSM), and the distribution pattern of the magnetic chains in the slurry was observed using a CT scan and an optical microscope. The retention rate of the slurry in moving water was tested using an anti-scour test. The results show that the magnetisation rate of the slurry increases linearly with an increase in magnetic powder doping, the magnetisation rate with 35% magnetic powder doping is 6. 89 times that with 5%. The rheological curve of the slurry conforms to the Bingham model and the dynamic yield stress increases with an increase in magnetic field strength. Magnetic particles are arranged in short chain, long chain, double chain, and bundle chain forms. When the water flow velocity is 0. 8m/s, the retention rate of the slurry is increased by 8. 68 times compared to ordinary slurry. This study provides theoretical guidance for the mechanism of magnetic slurry.