Due to economic and environmental concerns, optimizing the reuse and minimizing disposal of used bentonite slurry are imperative in geotechnical engineering. Despite the desanding process, the slurry may retain silt clay-size soil particles that are difficult to eliminate. This presents a challenging problem in soil excavations. Hence, it is imperative to assess the adaptability of the slurry containing silt clay soils. In this study, water–bentonite–kaolin slurries with varying kaolin contents were first prepared. The rheological properties of these slurries were assessed using a concentric cylinder rheometer, and the hydraulic properties of the resulting cakes were tested through static pressure filtration. The results indicate that adding a small amount of kaolin did not notably alter the rheological properties. A significant increase in yield point and viscosity was observed only at high kaolin solid content. Higher-density slurries tend to form thicker filter cakes with a denser structure. Furthermore, the implications for engineering practice were also provided.